Abstract
The animal body is composed of a variety of cells and extracellular matrices that are organized and orchestrated in a harmonized manner to support life. Therefore, the critical importance of a comprehensive understanding of the molecular network surrounding and integrating the cells is now emphasized. The CCN family is a novel group of matricellular proteins that interact with and orchestrate a number of extracellular signaling and matrix molecules to construct and maintain living tissues. This family comprises six distinct members in mammals, which are characterized by a unique and conserved modular structure. These proteins are not targeted to limited and specific receptors to execute specific missions, but manipulate a vast number of biomolecules in the network by serving as a molecular hub at the center. The unified nomenclature, CCN, originates from a simple acronym of the three classical members, which helps us to avoid having any preconception about their pleiotropic and anonymous functional nature. In this review, after a brief summary of the general molecular concepts regarding the CCN family, new aspects of each member uncovered by recent research are introduced, which represent, nevertheless, only the tip of the iceberg of the profound functionality of these molecules.
Introduction
More than two decades have passed since the discovery of the first CCN family member, CCN1. Initially, this gene product was identified as a cysteine-rich protein that was induced by growth factors and, thus, designated Cyr61. The second and most well-known member, CCN2, was isolated as a platelet-derived growth factor-related protein with mitogenic activity. The original name of this molecule, connective tissue growth factor (CTGF), was given based on this functional property. Thereafter, a gene structurally related to the two described above was found to be overexpressed as a truncated form in nephroblastoma, which resulted in the designation of this protein as nephroblastoma-overexpressed (NOV). Thus, the name of this family of three genes/proteins was proposed based on the names of these classical members (1–5). Although the discovery of the other three members occurred after this proposal, proper names other than CCN family-based ones were given as well. Among the different names given for these ‘nonclassical’ members, WISP1, 2, and 3 (2) have been widely accepted and are being preferred by several research communities even now.
In the early days of the investigation into each CCN family member, major progress was made under the bondage of the original name. As typically represented by the classical name of CCN2, researchers tend to regard these extracellular moiety molecules as growth factors or related proteins and analyzed CCN family members from the viewpoint of being extracellular messengers. Thus, a number of researchers spent a vast amount of time in determining the unique receptor for each.
However, as the research progresses, we have become aware that CCN family members are not messengers with highly specified missions, but rather novel molecules that manipulate a number of counterparts to regulate the whole information network. Nowadays, most investigators recognize that CCN family member interacts with multiple molecules in their microenvironment rather than only with a unique receptor on a target cell. Along with the understanding of such molecular behavior of the CCN family, it has gradually become clear that CCN family members may be playing critical roles in multiple organs and tissues. For example, the function and role of CCN2 in connective tissues and malignancies were extensively characterized, and a vast number of publications appeared in these categories (1–5). However, recent studies are now revealing the role of CCN2 in the development of Alzheimer’s disease (5). As such, in this review, following the introduction of the molecular and genetic characteristics of the CCN family, recent knowledge about each member playing significant roles throughout the body will be summarized in an organ/tissue-wise manner. This review concludes with our personal outlook and opinion about future research into this intriguing family of biomolecules.
Structure and molecular properties
The basic structure of the CCN family proteins is strictly conserved among the members and among various species. These proteins are constructed to have four distinct modules, which are the most prominent structural characteristics of this family, with minor exceptions (1–5). Following the signal peptide for secretion through the endoplasmic reticulum, the insulin-like growth factor binding protein-like (IGFBP) module is located near the amino-terminus. Then, von Willebrand factor type C repeat (VWC) and thrombospondin 1 type I repeat (TSP1) modules are connected in this order to be concluded by the carboxy-terminal cystine knot (CT) module (Figure 1). Interestingly, this order, IGFBP-VWC-TSP1-CT, has been strictly conserved during evolution and, thus, has never been shuffled. However, dimodular or trimodular variants are occasionally formed through alternative splicing of the mRNAs or proteolytic cleavage of the full-length molecule by matrix metalloproteinases (MMPs) and other proteases (6–8; Figure 1). Even single modular variants have been suggested in the case of human CCN2 and CCN4 (4, 9).
Structure of CCN family proteins.
Each CCN family protein comprises four conserved modules known as insulin-like growth factor binding protein-like (IGFBP), von Willebrand factor type C repeat (VWC), thrombospondin 1 type 1 repeat (TSP1), and carboxyl-terminal cystine knot (CT) modules. The amino-terminal and carboxyl-terminal halves are linked by hinge regions (wavy lines) that are susceptible to proteolytic processing. Molecules with a colored background were confirmed at protein levels, whereas those without color were detected only at the mRNA level. Approximate positions of in vitro cleavage sites attacked by endoproteases are indicated by arrows and the names of the corresponding enzymes.
During the course of animal evolution, the CCN family is thought to have been born after the branching of animals into the bilateria lineage. At present, a single distinct CCN prototype is found in amphioxus, sharing closest homology to our CCN2 (10). As the modules constituting CCN family proteins are encoded in independent exons and can be found in other related protein families, such as SPARC and IGFBPs, CCN family genes are suspected to have been formed through exon shuffling (10). After the birth of the CCN2 prototype, the other members probably evolved through gene duplication and rearrangement. As a result, four CCN family members became established in the urochordates, all of which members retain homology with human CCN1 and CCN2. Finally, we mammals possess six CCN family members with four modules aligned in this order, only one of which lacks the CT module. The fact that no variation is allowed in the order of the module alignment suggests its critical importance for these molecules; nevertheless, the structural and functional significances of this IGFBP-VWC-TSP1-CT order still remain to be clarified. At present, little is known about the tertiary structure of the CCN family proteins. One previous report indicated that CCN3 and CCN5 are rich in β-strands and random coils, as evaluated by circular dichroism spectrum analysis and that both form extended, rather than globular, shapes in solution as determined by X-ray scattering analysis and in silico modeling (11). Further structural characterization may clarify the functional role of such novel structural features of CCN family proteins in the future.
From the viewpoint of function, one should note that all of these modules are highly interactive with a number of other molecules (4). These molecular counterparts include, as detailed in the next section, growth factors, extracellular matrix (ECM) components, cell-surface receptors, and structural proteins, i.e., almost all kinds of biomolecules. Using these four ‘hands’, CCN family proteins orchestrate the molecular network by manipulating these molecular counterparts (Figure 2). Even direct interaction between two CCN family members, CCN2 and CCN3, has been recently reported (12). As CCN family proteins, themselves, may interact with signal-transducing, cell-surface receptors, they may initiate intracellular signal transduction per se. However, on the other hand, they may be modulating the activity of other molecules at the same time. Consequently, the biological outcome as a consequence of such multiple actions of CCN family proteins is quite diverse, highly depends upon the microenvironment, and thus is sometimes unpredictable or unexpected.
Interactomic representation of CCN family and cofactors.
Direct binding between two molecules, as confirmed experimentally, is indicated by bidirectional arrows. Interaction between CCN2 and CCN3 is indicated as a red arrow to avoid confusion.
Multiple molecular counterparts
CCN1
The interaction between the CCN family of proteins and integrins constitutes a major part of the functionality of these proteins (Figure 2). Particularly, the CCN1-integrin connection was discovered in the early days of CCN family research and has been extensively investigated. In fact, CCN1 binds to a number of integrins including αvβ3, αvβ5, αMβ2, and α6β1 to mediate adhesion of various types of the cells and other cell biological responses, such as cytokine production (5, 13). Heparan sulfate proteoglycans are the other major family of the CCN1 molecular counterparts, representing the molecular property of CCN1 as a matricellular protein to facilitate cell signaling (5, 14). As an accessory ligand, CCN1 interacts with a huge cell-surface receptor known as low-density lipoprotein (LDL) receptor-related protein (LRP)-1, contributing to apoptotic signaling (15). The binding of CCN1 to vitronectin also suggests the involvement of this ECM molecule in the matricellular action of CCN1 (16). Of note, sclerostin, which is a Wnt signal inhibitor produced by osteocytes, was found to regulate CCN1 activity by direct interaction, indicating the presence and possible role of CCN1 in bone metabolism (17).
CCN2
CCN2 is the most extensively investigated one among the six members. During the history of CCN2 research, it has been revealed that CCN2 shares common functionality with CCN1 under the interaction with common biomolecules. The most prominent examples of such molecules are the integrins and HSPGs. In fact, CCN2 exerts effects comparable to those of CCN1 by binding to exactly the same integrins on the same cells (5, 13, 18). In addition, LRP1 is another example of a common cofactor, although the target cell and biological outcome are totally different between CCN1 and CCN2 (15, 19). However, it is a matter of course that CCN2 also interacts with its proper partners in exerting CCN2-specific functions. As a matricellular protein, CCN2 binds to fibronectin and aggrecan, which are major components of the ECM (20, 21). Other counterparts include cell-surface receptors, such as receptor activator of NF-κB (RANK; 22), LRP6 (23, 24), TrkA (25), fibroblast growth factor (FGF) receptor (FGFR) 2, and FGFR3 (26). It should be particularly noted that CCN2 interacts with a number of growth factors, which include transforming growth factor β (TGF-β), bone morphogenetic protein (BMP) 2, BMP4, FGF2, vascular endothelial cell growth factor (VEGF) and Slit 3, a molecule that activates Rho family members to promote cell migration (21, 27–29). In most cases, CCN2 was found to modulate the signal emitted from these molecules via direct interaction. Additionally, CCN2 manipulates modifiers of extracellular signaling. For example, Wif1, an inhibitory molecule of Wnt signaling (30) and osteoprotegerin (OPG; 22), which is a decoy receptor of RANK, recently joined the community of CCN2 partners. Obviously, multiple interactions with these molecules are providing the basis for CCN2 to exert diverse biological effects in various organs and tissues, which are described in other sections of this review.
CCN3
Binding not only to integrins, CCN3 was found also to bind to Notch (5), fibulin (2), and BMPs (5). In particular, the interaction between CCN3 and BMP2 was suggested to play a critical role in the negative regulation of bone formation (5). Integrins were found to support the angiogenic effect of CCN3 (4). As already stated elsewhere, CCN3 is currently the only CCN family member that has been shown to form a heterodimer with CCN2, although heteromer formation has not yet been examined with other combinations of distinct CCN family members (12).
CCN4–6
Compared to the three prototypic members discussed above, not so many molecular counterparts have been discovered for the other three members identified later. Nevertheless, all of these members were found to interact with integrins as well. Interaction with integrins supports the IL-6 production stimulated by CCN4 (31), neurite formation by CCN5 (32), and chondrocyte migration by CCN6 (33). BMPs were also described as cofactors for CCN4 (34) and CCN6 (35). Recent advances in CCN6 research identified novel cofactors for this last member of the CCN family. These molecules include BMPs (35), LRP6 (36), frizzled (36), and IGF1 (37), suggesting the role of CCN6 as a modifier of Wnt and insulin/IGF signaling.
Gene structure and regulation
CCN family in the genome
As already mentioned above, we mammals possess the genes of six CCN family members in our genome. Among them, those of CCN1 and 2 are characterized by their compact structures with minimal introns, giving total genomic sizes of approximately 3 kbp (38). Conversely, CCN4, 5, and 6 that joined the CCN family after its establishment, exceed 10 kbp in total size due to larger introns. Especially, CCN4, the largest member, occupies a locus as long as 40 kbp on chromosome 8 of the human genome. CCN3 is intermediate between the two groups in size (38). The compact structure of CCN1 and 2 suggests that these members are the prototypes of this family, which notion is supported by the early emergence of these members along the course of evolution. However, it is not clear whether CCN3 appeared next, or not, as CCN3 is not necessarily the third ortholog predicted in early chordata. For example, the lamprey genome contains four CCN family members, among which three are homologous to CCN1, 2, and 6, whereas the other one is not homologous to any specific member.
In the viewpoint of gene function, structural characteristics of these members are closely related to the formation of transcripts. No splicing variants that yield different species have been reported or predicted in the case of CCN1, 2, and 3 with concise genetic structures. By contrast, a number of CCN4, 5, and 6 mRNA variants encoding different combinations of modules have been predicted and experimentally shown to be present in certain human cells, probably because of the large introns (4, 9; Figure 1). As such, the bulky structures of CCN4, 5, and 6, themselves, supposedly contributes to the complexity of their gene function.
Every mRNA contains untranslated regions (UTRs) at both the 5′ and 3′ ends. It should be noted that all of the CCN family members except for CCN6 are commonly characterized by the retention of their 3′-UTRs of considerable lengths (38). As described in the next section, these 3′-UTR have been shown to be fundamental regulators of the fate of the mRNA.
CCN regulators and their action
Extracellular CCN regulators and relevant signaling molecules
The functionality of CCN family members highly depends upon the microenvironment, indicating that the function of a CCN family protein, itself, is determined by the temporal and spatial regulation of gene expression. Up to today, a number of biomolecules have been found to regulate CCN family gene expression. As positive regulators of CCN family gene expression, TGF-β is probably the best known, whereas inflammatory cytokines, such as TNF-α, are generally recognized as being negative regulators of several CCN family genes (39, 40). The involvement of these molecules is of great interest, as some of the CCN family members have recently been suggested to be associated with inflammatory processes. Particularly, the mechanism and biological significance of the CCN2 induction by TGF-β have been extensively investigated. CCN2 is transcriptionally induced by TGF-β through multiple pathways (3). Indeed, TGF-β physically interacts with CCN2, induces CCN2, and collaborates with CCN2 in certain biopathological situations, such as fibrogenesis (5). TGF-β is attracting the interest of medical scientists also as a mediator of the epithelial-mesenchymal transition (EMT), enhancing CCN1, CCN2, and CCN4 expression, while repressing CCN3 expression (39, 40). As another multiple CCN regulator, glucocorticoids enhance the gene expression of CCN1, CCN2, and CCN5 (39, 41). However, in mice, the induction of CCN2 by dexamethasone is strain dependent (42), and CCN5 induction in humans has been confirmed, so far, only in estrogen receptor (ER)-negative breast cancer cells.
In addition to these molecules, an earlier investigation revealed platelet-derived growth factor (PDGF) and epithelial growth factor (EGF) to be a potent inducer of CCN1 (43). Later on, substance P (44) was also found to enhance CCN1 gene expression through mitogen-activated protein kinase (MAPK) pathways and a histone deacetylase complex (HDAC)-dependent pathway, respectively. Clinically, the effect of zoledronate, a drug that represses bone metastasis of tumors, on CCN1 via FOXO 3a is worthy of note in relation to breast cancer chemotherapy (45). The induction of CCN1 in skin fibroblasts by cigarette smoke through Egr1 also suggests a possible role in CCN1 in skin aging due to smoking (46). Other classical CCN2 inducers include angiotensin II and endothelin, the latter of which mediates, in part, the TGF-β-induced enhancement of CCN2 gene expression (3, 21, 47). Recent advances in CCN2 research also found secreted frizzled-like protein 2 (sFRP2) and an antiproliferative factor as CCN2-inducing proteins (48, 49). Significant roles of signal transducers and activators of transcription (STATs) in CCN2 induction have been suggested in the up- and downregulation of CCN2 by thrombin and IFN-γ, respectively (50, 51). The natural compound curcumin inhibits thrombin and TGF-β-induced CCN2 expression through multiple signaling pathways (52, 53). Nicotine is also known to induce CCN2 production in periodontal and pulmonary artery smooth muscle cells, suggesting the contribution of CCN2 to nicotine-induced tissue remodeling in response to smoking (54, 55). Interestingly, matrix metalloproteinase (MMP)-3, which is widely recognized as an extracellular proteinase, was found to regulate CCN2 by acting as a transcription factor (56, 57). The story of such transcription factors follows this subsection.
Novel factors that drive the expression of other CCN members are being discovered as well. According to a recent study, CCN3 is under the regulation of interleukin (IL)-3 and plays a critical role in the hematopoietic system (58). CCN4 was found to be induced by Notch activation, nitric oxide production, and a nephrotoxin in dermal cells, colitis, and renal cells, respectively (59–61), indicating pathophysical roles of CCN4 in these tissues. In addition, enhancement of CCN5 expression by IGF-1 is reported to occur in ER-positive breast cancer cells (62).
Apart from biomolecules, hypoxia, mechanical stress, and UV irradiation also significantly affect CCN family gene expression (5). Hypoxia triggers the production of both CCN1 and CCN2 (63). Of note, a vast number of reports have described the induction of CCN2 by various forms of mechanical stresses in a variety of cells, where signals through Rho family members play a central part (63, 64). Recent progress in molecular medicine is revealing the utility of low-intensity pulsed ultrasound (LIPUS) as a physical therapeutic to accelerate tissue regeneration, which is accompanied by enhanced CCN2 production (65).
Transcriptional and posttranscriptional regulation of CCN family members
After intracellular signal transduction has occurred, gene expression of CCN members is performed at the transcriptional or posttranscriptional level. Such regulatory systems of gene expression inside cells have been extensively investigated in the case of CCN2 (Figure 3), whereas, relatively, little is known for the others. As classical transcription factors that drive CCN2 transcription, Ets1 (66), p53 (67), Hif1α, Smads, SP1 (3), NF-κB (63), FoxO3a (68), TAZ (69), and STATs (50, 51) may be listed (5, 21). Among them, p53 is suggested to be involved in CCN5 expression as well (70). The most interesting molecule that mediates the transcriptional regulation of CCN2 is MMP-3. This particular extracellular protease can be internalized into cells and become localized in the nucleus (56, 57). Furthermore, nuclear MMP-3 was found to interact with the CCN2 gene in the chromatin structure and actually to activate the transcription of the gene. Activation of CCN2 by MMP-3 was reported to occur in two different types of the cells by independent research groups (56, 57). For the expression of CCN3 in rhabdomyosarcomas, PAK3-FKHR is the only indicated transcription factor so far (71). Further research on the transcriptional regulation of other CCN members is to be desired.
Transcription and posttranscriptional factors regulating the CCN2 gene.
Transcription factors that directly regulate the transcription of the CCN2 genes are summarized in a box over the schema representing the genomic structure of the CCN2 gene. Open and blue boxes indicate untranslated and coding exons, respectively, and introns are represented by black lines. Posttranscriptional factors including miRNAs are similarly summarized in the box below the illustration of the CCN2 mRNA. The approximate location of the cis-acting element of structure-anchored repression (CAESAR) is indicated by a box, together with the secondary structure of this element at the bottom. Note that the predicted target of miR-145 (shown in pink) is located within the accessible major loop therein.
Concerning posttranscriptional gene regulation, significant knowledge is available for CCN2, most of which is asserting the critical importance of the 3′-UTR of its mRNA. After the discovery of a cis-acting element for structure-anchored repression (CASEAR) in human and murine CCN2 mRNAs (72–74), another RNA element was discovered in chicken CCN2 mRNA, one that regulates the stability of CCN2 mRNA via direct interaction with a nucleocytoplasmic shuttling protein, nucleophosmin (75). It is widely recognized that regulation of gene expression by microRNAs (miRNAs) is mostly performed via the 3′-UTRs. Consistent with this notion, several miRNAs have been described to target CCN2 mRNA at its 3′-UTR, which seem to play proper roles in corresponding organs and tissues (76, 77). Interestingly, one such target of miRNAs is located on the major loop of CAESAR, suggesting common regulatory components shared between the regulatory systems mediated by these two elements (Figure 3). Considering that a few reports showing the repressive regulatory function of the CCN1 3′-UTR are being published (78), related information may be available shortly on the other members as well.
Of note, posttranscriptional regulatory systems mediated by regions other than the 3′-UTR have been reported for CCN1. In chicken CCN1, a coding segment on the mRNA supports the expression of CCN1 by facilitating ribosomal recruitment (79). Another report suggests that miR-181a represses CCN1 at a posttranscriptional stage of gene expression, which is mediated by a region outside of the 3′-UTR (80). Progress in similar research on other CCN family members will clarify the solid contribution of miRNAs to the regulation of the CCN family genes.
CCN family proteins as transcription factors
Despite their properties as secretory proteins with signal peptides, several reports suggest possible functionality of certain CCN family members as transcription factors. Surprisingly, CCN5 is actually recruited to the promoter of a TGF-β receptor gene in the nucleus to suppress TGF-β signaling (81). Additionally, a few other CCN members are also found in the nucleus (5), suggesting their intracrine function, possibly for gene regulation.
The CCN family in development and growth
Skeletal system
Our skeletal system is formed through a combinatory developmental system composed of two modes of bone formation: one is intramembraneous ossification, whereas the other is endochondral ossification. The former process was established early in the history of animal evolution to arm the body with an exoskeleton by direct ossification, when only a CCN prototype was present at that time (82). The latter process is initiated by the formation of cartilage anlagen of bone parts, followed by their growth and subsequent ossification after the terminal differentiation of chondrocytes, designated hypertrophy. On the way to the establishment of this endoskeletal system, the members of CCN family appear to have increased in importance, suggesting the critical role of this family in this system (2, 82, 83). First of all, it should be noted that all members of the CCN family are produced during particular stages of endochondral ossification (82–84). Consistent with this notion, the profound role of this family in the skeletal development of vertebrates has been extensively characterized and reported. The initial report describing the involvement of a particular CCN family in skeletal development appeared in 1997. In that study, CCN2 was rediscovered as a factor that was overexpressed in hypertrophic chondrocytes in the growth-plate cartilage of mouse bones and, thus, was designated as hypertrophic chondrocyte-specific gene product 24 (Hcs24; 21, 82, 83). Thereafter, a vast number of studies revealed the critical role of CCN2 in skeletal development. Indeed, CCN2 was found to promote both the proliferation and differentiation of chondrocytes, osteoblasts, and vascular endothelial cells, which are central players of both endochondral and intramembranous ossification. These findings were further confirmed by in vivo studies on Ccn2-null mice and rat models of cartilage/bone regeneration (21, 84, 85). Nowadays, CCN2 is recognized as a potential therapeutic material for cartilage/bone regeneration (86, 87).
The contribution of CCN1 to chondrogenesis, which is indispensable for the early events of endochondral ossification, has been clearly demonstrated (5). Nevertheless, the role of CCN1 in later events in this process is still unclear. In contrast, CCN4 was reported to promote the ossification process by enhancing BMP function (34), whereas its effect on chondrogenesis has not been described. At the time of its initial discovery, CCN5 was described as a factor that promotes osteoblast differentiation in vitro (82); however, no additional information is available to date, except for one report describing a limited osteogenic effect in vitro (88).
Recent advances in CCN family research are unveiling an interesting aspect of CCN3 function in skeletal development. In the early days, CCN3 was found to promote angiogenesis in vitro (4) and was also defined as a positive regulator of chondrogenesis (89), but a number of later studies indicated that CCN3 rather counteracts bone formation when interacting with BMP-2 (5, 90). The fact that endochondral ossification is delayed in Ccn2-null mice, in which animals display elevated CCN3 expression, also indicates the inhibitory action of CCN3 toward skeletal growth (84). The apparent contradiction observed between the chondrogenic and anti-osteogenic effects of CCN3 was recently found explainable based on the findings described by Janune et al. (91). In their report, CCN3 was shown to direct the maturation of chondrocytes toward articular chondrocytes, while inhibiting the terminal differentiation toward ossification (91). Thus, CCN3 is now believed to play a significant role in constructing and maintaining articular cartilage, which connects skeletal parts in joints, and this role is consistent with the phenotypic change observed in CCN3 mutant mice (92).
In view of joint development, CCN6 has been attracting the interest of medical scientists because of its association with an inheritable joint disease known as progressive pseudorheumatoid dysplasia (PPD; 5). A variety of mutations in human CCN6 gene were found in PPD patients, and such mutations affect both BMP and Wnt signaling (36, 93), which may account for the pathogenesis of PPD at least in part. As CCN6 is also present in normal articular cartilage and seems to prevent hypertrophy by interacting with insulin growth factors (IGFs), this particular CCN family member is probably involved in normal joint formation (94, 95).
Cardiovascular system and angiogenesis
Through the characterization of knockout mice, only one CCN family member, CCN1, is known to be indispensable for cardiac development (10, 96). The other CCN family members are not a critical determinant of cardiovascular development, as cardiogenesis and vasculogenesis, themselves, can be carried out, even in the absence of one such member. Nevertheless, all CCN members have been shown to modulate the development and maintenance of cardiovascular tissues under proper biological and pathological situations. Therefore, CCN family members are anticipated to collaborate with each other in the developing cardiovascular system. A deficiency in a single member, except for CCN1, can be efficiently compensated by the other members in most events occurring in vivo.
Angiogenic activities of all three of the classical members, CCN1, CCN2, and CCN3, were confirmed both in vivo and in vitro, where integrins are required as their partners (4, 5). Among these classical members, CCN1 promotes all types of vascular developmental processes; hence, this factor is indispensable for the integrated development of the fetal vascular system. Such properties of CCN1 are firmly confirmed by the phenotype of Ccn1-null mice, which have severe defects in chorioallantoic fusion and in the placental blood vessel system (5, 97). Furthermore, physical defects are also found in both atrial and ventricular septa in such mice (96). Albeit at a milder level, vascular development in Ccn2-null mice is also impaired. This impairment is typically represented by delayed vascular invasion into the bone tissues, which delay leads to skeletal defects causing respiratory failure (85). In addition to the vasculature-forming activity under experimental conditions (4), the angiogenic activity of CCN2 is further emphasized in the context of angiogenesis in skeletogenesis and tumor angiogenesis (4). CCN2 is induced by hypoxia and promotes bone metastasis of breast cancer cells (4, 98, 99). Here, it should be noted that CCN6 is known to contrarily repress breast cancer invasion through multiple pathways (100, 101). In contrast to that of CCN1 and CCN2, the role of CCN3 in vascular development has not yet been clearly established, in spite of its angiogenic property.
After development, several CCN family members are expressed in cardiovascular tissues under pathological conditions. CCN3 was found to counteract neointimal hyperplasia by repressing the proliferation of vascular smooth muscle cells (102). A similar effect on vascular smooth muscle cells was also observed for CCN5 (4). Finally, both CCN2 and CCN4 have been regarded as a promoter and biomarker of cardiac hypertrophy and fibrosis (4, 103, 104); but a recent report contrarily describes the cardioprotective effects of CCN2 against chronic cardiac stresses (105). This finding also appears contradictory to the fact that CCN5 exerts similar cardioprotective effects in the transgenic mice (5).
Hematopoietic system
In light of the heavy trafficking of growth factors and cytokines, CCN family members, except for CCN3, are currently anticipated to play relatively minor roles in the development of cells of the hematopoietic lineage. CCN2 is found in abundance in platelets (82), but this platelet-encapsulated CCN2 does not seem to be produced by the platelet producer, i.e., the megakaryocyte. Instead, nascent platelets are thought to incorporate CCN2 that is supplied by mesenchymal cells in the bone marrow (106). CCN2 is one of the important components of platelets, which initiate and promote the wound healing process, as the critical role of CCN2 in wound healing has been emphasized in a number of previous reports (3–5). Thus, if the CCN2-containing ones are defined as mature platelets, the mesenchymal-hematopoietic interaction to supply CCN2 would be the final step of thrombopoiesis. In addition, the inclusion of the other CCN family members into platelets has not yet been assessed, and thus, this possibility ought to be examined.
Compared to CCN2, the contribution of CCN3 to the hematopoietic system is more profound and fundamental. In general, CCN3 function is closely related to the ‘stem cell-ness’ of cellular progenitors, rather than to the lineage development. In normal bone marrow, CCN3 is secreted by hematopoietic progenitor cells and is also present in human serum. This molecule is required for the stem cell renewal and the maintenance of naïve hematopoietic progenitors, in which interaction with Notch plays a major role. In addition, CCN3 is required for the development of cells of the myelomonocytic and erythroid lineages, and for facilitating B-cell development as well (107, 108). Such CCN3 functions appear to be highly specific to CCN3, as no functional redundancy or compensation by another CCN family member has been observed.
Nervous system
For a significant period of time, investigation into the relationship between the CCN family and the nervous system had been mostly ignored. This was probable because both representative members, CCN1 and CCN2, were identified and characterized mainly in the context of mesenchymal tissues. Additionally, it may be pointed out that, because of the embryonic lethality of Ccn1 and Ccn2 null mice, loss-of-function studies on the central nervous system were difficult. Therefore, although a few early studies implied a possible function of CCN2 in the nervous system, as indicated by immunohistochemical localization (109) and molecular interaction of CCN2 with neuronal factors (110), a decade was spent thereafter to find out the actual behavior and functionality of CCN family members.
One of the most striking reports concerning CCN1 describes the requirement of this protein for dendritic growth of hippocampal neurons (111). Of note, this process is also dependent upon the interaction of CCN1 with integrins. In spite of the absence of distinct evidence indicating a physiological role of CCN2 in neuronal tissue development, the role of CCN2 in the development of Alzheimer’s disease has been indicated and discussed (39, 112). Consistent with the expression of CCN3 during the development of the central nervous system, CCN3 was recently found to be produced by Purkinje cells and to promote the maturation of cerebellar granule neurons by acting in a paracrine manner through integrins (113). In relation to Alzheimer’s disease and other neurodegenerative disorders, CCN4 was described as a cytoprotective agent against oxidative stress and β-amyloid-induced neuronal cell death (114). CCN5 expression is upregulated in the central nervous system of ganglioside-deficient mice, and in these animals, there are positive effects of CCN5 on neurite formation, which action is mediated by the integrin-AKT signaling pathway (32). These findings suggest that these two CCN family members are able to protect the central nervous system upon possible disorder, even if they are not definitely required for the normal development of this system.
Other organs
The pancreas is not only a major exocrine producer of digestive enzymes but also an endocrine producer of critical hormones including insulin. The expression and functionality of CCN2 during the development of islet morphogenesis and the proliferation of β-cells during embryonic development have been unveiled by recent studies (115). Concerning the eyes, vascular network formation is a critical step in both physiological development and establishment of major eye disorders. Although its precise molecular function is unclear, dynamic expression of CCN1, CCN2, and CCN3 is observed during mammalian eye development with overlapping spatiotemporal expression patterns (116, 117). Expression and a possible role of CCN2 in the development of tooth germs were indicated as well (118). In these organs, however, the roles of the other CCN family members still remain to be investigated.
The CCN family in biological responses and diseases
Fibrosis
The CCN family is probably the best known in the context of the fibrogenic role of CCN2. In fact, overexpression of CCN2 is observed in most fibrotic disorders in a number of organs and tissues (5, 82). Conversely, overexpression of CCN2 successfully produces experimental fibrosis in several in vivo systems (5). Therefore, it had once been believed that CCN2 could be the sole developer of fibrosis. Nevertheless, recent advance in CCN research is illustrating that fibrosis is an outcome of an imbalance in the CCN family network during the tissue regeneration process.
Fibrosis is the outcome of a continuous failure of tissue regeneration. According to recent studies, not only CCN2 but also CCN4, exerts profibrotic effects in cardiac fibrosis (104). CCN3 counteracts these effects by downregulating these molecules at gene expression and molecular function levels and through other unknown mechanisms (119). As described elsewhere, TGF-β induces the expression of CCN1, CCN2, and CCN4 while repressing that of CCN3. TGF-β is known as an enhancer of ECM production, or a profibrotic factor; hence, the behavior of CCN2, CCN4, and CCN3 downstream of this molecule is quite understandable. However, CCN1 does not act as a profibrotic factor. What is the role of CCN1 herein? A possible answer was given by studies by Jun and Lau (5, 120). In those studies, CCN1 was found to induce dermal fibroblast senescence by binding to integrin and HSPG through the induction of DNA damage response pathways and the generation of reactive oxygen species (ROS). As a result, fibroblasts undergo senescence and express antifibrotic genes. Therefore, CCN1 is integrating the formation of a proper ECM in collaboration with fibrotic CCN family members (5).
In the kidney, chronic fibrosis is incurred by several etiological factors including hyperglycemia and its secondary products, in which the balance between CCN1 and CCN2 plays a pivotal role. During the development of diabetic nephropathy, both CCN1 and CCN2 are induced, following different time courses with different missions in an attempt to repair the damaged glomeruli. However, along with the fading out of CCN1 induction, fibrotic changes progress at later stages (63, 121). Consistent with these findings, CCN1 inhibits the migration of mesangial fibroblasts, whereas CCN2 promotes fibrotic changes in the kidney (63, 122, 123). Of note, CCN3 is reported to be involved in the regulation of renal fibrosis, counteracting CCN2 gene expression (124). Collectively, these findings clearly represent the scenario of fibrosis regulation via the CCN family network, although the behavior of CCN4 remains to be investigated.
The lung is another major organ in which CCN2-mediated fibrosis is commonly reported (1, 3, 5, 82). The involvement of CCN4 in a few types of pulmonary fibrosis is also recognized (125). Lung fibrosis can be induced by a number of endogenous and exogenous factors including iatrogenic ones. Interestingly, CCN6 was found to be induced in a pulmonary fibrosis model of mice treated with bleomycin (126). Subsequent investigation in vitro revealed relatively weak fibrogenic activity of CCN6. Although further study to verify its biological significance is necessary, CCN6 may also join the CCN family network for fibrosis regulation as a profibrotic member (126).
The antifibrotic function of CCN1 via integrin and HSPG-mediated provocation of cellular senescence is indicated in the fibrotic remodeling of liver tissue (127). This process is, as found in dermal fibroblasts, mediated by ROS formation. As a fibrosis-associated inheritable disease, skeletal muscle dystrophy was also found to be mediated by CCN2, as overexpression of CCN2 is able to mimic this clinical entity (128).
Inflammation
The profibrotic property of certain CCN family members strongly suggested their involvement in inflammatory processes, especially in chronic inflammation. This notion is also emphasized by the anigiogenic properties of certain CCN family members. As such, inflammatory aspects of CCN family function were uncovered subsequently by later studies (39).
The facts that the gene expression of CCN family members is under the regulation of chemical mediators of inflammation, and these members also regulate the expression of genes of proinflammatory proteins, indicate that these members are firmly built into the network of the biodefense system. As already stated elsewhere, CCN1, CCN2, and CCN4 are all upregulated by TGF-β and downregulated by TNF-α, whereas CCN3 is regulated by the same cytokines in the opposite manners (39). The induction of CCN1, CCN2, and CCN3 by substance P (45), MCP-1 (129), and IL-10 (39), respectively, has also been reported. Multiple regulation of CCN2 by small chemical mediators such as nitric oxide (NO), histamine, serotonin, and prostaglandins, is also known (39). As classical downstream mediators of the CCN family members during inflammation, MMPs that play major roles in inflammation and tissue remodeling are widely known. CCN1 was found to induce MMP-13 (130), and CCN2, to induce a variety of MMPs via multiple regulatory systems (131). The induction of MMP-1 and MMP-3 by CCN3 was also reported (132). In contrast, CCN4 and CCN5 downregulate MMP1 and MMP-2, respectively (133, 134). These findings, again, assert the role of CCN members as the principal coordinators of ECM remodeling.
A few recent studies revealed a novel mode of cytokine induction by the CCN family (Figure 4). Clinically, the level of CCN1 or CCN2 is enhanced in rheumatoid arthritis (RA) joints (13, 18, 67), whereas in osteoarthritis (OA), increased levels of CCN2 and CCN4 are observed in the synovial fluid of inflamed joints (18, 31). Interestingly, all three members stimulate inflamed synovial fibroblasts to produce IL-6, which may promote the differentiation of T cells into those of a Th17 subpopulation (13). Surprisingly, CCN1, CCN2, and CCN4 share integrin αvβ5 as a common receptor and NF-κB as a common transcription factor to provoke IL-6 gene expression (4, 13, 21). Nevertheless, the intracellular signaling pathways they use are not exactly identical; i.e., CCN1 and CCN4 eventually activate NF-κB through the PI3K-AKT pathway, whereas CCN2 initiates ASK activation under integrin αvβ5, leading to NF-κB and AP-1-mediated enhancement of IL-6 gene expression. The mechanism by which different signaling pathways can be differentially activated through the same receptor remains to be clarified, but probably can be ascribed to the difference in the types of collaborators acting together with integrin αvβ5 and these CCN family members.
Overview of the signaling for IL-6 induction in inflamed synoviocytes by CCN family members.
Upper and lower arcs denote plasma and nuclear membranes, respectively. The objects depicted on the plasma membrane represent integrin subunits. CCN1 and CCN4 principally use the PI3K-AKT pathway at the right, whereas CCN2 is reported to induce IL-6 via the ASK1-dependent dual transcriptional induction illustrated on the left.
Malignancies
An association of CCN family members with malignancies has been recognized in a vast variety of human tumors (5, 38). Although elevated expression of particular CCN family members is observed in the tumors, there is significant controversy regarding their pathological roles. For example, CCN2 promotes pancreatic tumor growth (115), whereas the same molecule suppresses the growth of oral squamous cell cancer by promoting epithelial differentiation (135). Considering the molecular nature of the CCN family, such context-dependent effects in view of tumor development is understandable.
Nevertheless, by viewing the association between the six CCN family members and relevant malignancies (Figure 5), several intriguing features may be pointed out (5, 136). First, all of the CCN-associated malignancies are related to either CCN1 or CCN2. In other words, no tumors that are associated with CCN3, CCN4, CCN5, or CCN6 alone have been specified so far. Notably, all malignancies that have association with CCN4, CCN5, or CCN6 are also related to both CCN1 and CCN2, emphasizing the major roles of these classical members in tumor biology as well. Second, only negative effects against malignant phenotype has been reported in the case of CCN5 and CCN6 up to now. Finally, it should be noted that breast cancer is now known to be associated with all of the CCN family members (5).
Comprehensive illustration of the organ-wise tumor-CCN family connection.
An organ or tissue name within a circle labeled by a CCN family member indicates the relevance between tumors originating from that tissue and the CCN family member. The area with both CCN1 and CCN2 connections in the upper panel is enlarged in the lower panel. WBC and MCT denote white blood cell malignancies (leukemia) and mesenchymal tumors (chondrosarcoma and osteosarcoma). Note that breast tissue, shown in red, is the only tissue in which all of the CCN family members are involved upon tumorigenesis or metastasis.
Breast cancer is one of the major clinical entities that cause the death of adult females in advanced countries. A positive or negative association with poor prognosis was reported for CCN1, CCN2, and CCN4, or CCN5 and CCN6, respectively (5). In the case of CCN3, a significant relationship between low gene expression and poor prognosis is observed in clinical cases (137), whereas CCN3 favors metastasis to bone by promoting bone resorption (138).
The promotion of bone metastasis by CCN2 was experimentally confirmed in animal models. Also, in the case of this particular type of tumor, CCN1 always acts to enhance tumorigenesis, tumor growth, metastasis, and even drug resistance (5). Therefore, CCN1 is now recognized as one of the promising targets for the chemotherapy against breast cancers.
Ocular diseases
The recurrence of angiogenic events after ocular development occasionally leads to neovascularization-related disorders in the eye (116). These diseases include proliferative diabetic retinopathy, age-related macular degeneration, and experimental oxygen-induced retinopathy (OIR), mimicking the retinopathy of prematurity in humans. In spite of the clear involvement of these CCN family members in these diseases, the pathological roles of CCN1 and CCN2 are, again, controversial. However, according to a recent study, the roles of these molecules in OIR development are reminiscent of those in nephropathy (116). Namely, additive expression of CCN1 reduced pathological angiogenesis without adverse effects, whereas silencing CCN2 exerted comparable effects in an OIR model (123, 139). These complicated effects by CCN1 and CCN2 are anticipated to result from their molecular interaction with VEGF and integrins. It is widely recognized that VEGF is the major growth factor that directs angiogenesis. First, both CCN1 and CCN2 directly bind to VEGF, which may control the availability and net angiogenic activity of these molecules, in collaboration with particular proteases that digest CCN1 and CCN2 (7, 8, 140). Second, the interaction between VEGF and integrins, which plays a significant role in the aberrant growth of blood vessels, may be affected by the CCN-integrin connection (5). Interestingly, a previous report showed that CCN2 levels correlate positively, but VEGF levels, negatively, with the degree of fibrosis in progressive diabetic retinopathy patients (141). CCN2-VEGF interaction may direct the pathogenic tissue remodeling of the retina toward either neovascularization or fibrosis. From this point of view, it is of particular interest that an amino-terminal dimodular fragment of CCN2 accumulates in the vitreous of patients with proliferative diabetic retinopathy (142).
Apart from these neovascularization-related diseases, the level of CCN2 is also increased in the case of glaucoma. Although CCN2 is expressed in the normal trabecular network to regulate aqueous humor outflow, an elevated level of CCN2 is found in glaucoma, together with TGF-β (143). As the expression of both CCN1 and CCN2 is responsive to mechanical stimuli, elevated expression of these genes induced by increased intraocular pressure may mediate the pathological changes constituting glaucoma (63). In addition, targeted deletion of a CCN3 module was found to cause cataract in mice (92). The involvement of CCN2 in this ocular disorder is also suspected, but still remains to be clarified.
Expert opinion
As introduced in this review, it is occasionally observed that more than one CCN family member play significant roles in the development and pathogenesis of the same organ or tissue. In typical cases, three out of six family members present in the same tissue exert almost identical effects on the same cells, as found in the case of those of CCN1, CCN2, and CCN4 on IL-6 production by synovial fibroblasts. In contrast, counteraction between two coexisting members, such as the combination of CCN2 and CCN3, is widely known under a variety of biological situations. Therefore, in order to uncover the molecular networks extending out from CCN family members in any biological microenvironment, comprehensive analysis taking all of the CCN family members into consideration is indispensable. Mutual direct molecular interaction, which was clarified by recent studies, and genetic regulation among the CCN family members further strengthen this critical notion.
Outlook
Life is the outcome of the integration of continuous interactions among multiple biomolecules, rather than the assemblage of biomaterials. In other words, the molecular interaction is as important as the molecule itself in understanding how life works, and the function of a particular molecule is variable depending upon its microenvironment. Therefore, both defining the proper function of and the function-based terminology for a molecule may be meaningless. CCN family members have taught us this critical concept. Nowadays, biologists are starting to reevaluate the ‘proper’ function of a number of molecules comprising the living body. After a few decades into the future, a significant number of extracellular signaling molecules may need to be renamed, just as CTGF metamorphosed into CCN2 in the past.
Highlights
The matricellular CCN family is a novel group of proteins that exert multiple functionalities by manipulating extracellular molecular networks.
The prototypic CCN is anticipated to be CCN2 with its compact gene structure, which has expanded up to six members in mammals during the evolution of vertebrates.
Typical members consist of four conserved modules that interact with a variety of growth factors, ECM components, and cell-surface receptors including integrins.
The function of CCN family proteins highly depends upon the cofactors in their microenvironment and, hence, is determined by spatiotemporal gene regulation.
Recent research has revealed that the CCN family is critically involved not only in the development of skeletal, cardiovascular, hematopoietic, and nervous systems, but also in that of the eyes and pancreas.
In addition to the well-known role of CCN2 in a number of fibrotic disorders, the involvement of most family members in inflammatory processes has also been uncovered.
Among various CCN family-associated malignancies, the contribution of all six family members is now recognized in the development of breast cancers.
Because of the copresence of multiple CCN members throughout the body, comprehensive investigation on all members is required for the total understanding of the extracellular information network that supports life.
This study was supported by grants from the program Grants-in-aid for Scientific Research (B) [#24390415 to M.T.], and (C) [#25462886 to S.K.] from the Japan Society for the Promotion of Science. The authors have no conflict of interest to declare. Also, the authors thank Ms. Yoshiko Miyake for her secretarial assistance.
References
1. Brigstock DR, Goldschmeding R, Katsube K, Lam SCT, Lau LF, Lyons K, Naus C, Perbal B, Riser B, Takigawa M, Yeger H. Proposal for a unified CCN nomenclature. Mol Pathol 2003; 56: 127–8.10.1136/mp.56.2.127Search in Google Scholar PubMed PubMed Central
2. Perbal B, Takigawa M. CCN protein – a new family of cell growth and differentiation regulators. London: Imperial College Press, 2005.10.1142/p384Search in Google Scholar
3. Leask A, Abraham DJ. All in the CCN family: essential matricellular signaling modulators emerge from the bunker. J Cell Sci 2006; 119: 4803–10.10.1242/jcs.03270Search in Google Scholar PubMed
4. Kubota S, Takigawa M. CCN family proteins and angiogenesis: from embryo to adulthood. Angiogenesis 2007; 10: 1–11.10.1007/s10456-006-9058-5Search in Google Scholar PubMed
5. Jun JI, Lau LF. Taking aim at the extracellular matrix: CCN proteins as emerging therapeutic targets. Nat Rev Drug Discov 2011; 10: 9459–63.Search in Google Scholar
6. Guillon-Munos A, Oikonomopoulou K, Michel N, Smith CR, Petit-Courty A, Canepa S, Reverdiau P, Heuzé-Vourc’h N, Diamandis EP, Courty Y. Kallikrein-related peptidase 12 hydrolyzes matricellular proteins of the CCN family and modifies interactions of CCN1 and CCN5 with growth factors. J Biol Chem 2011; 286: 25505–18.10.1074/jbc.M110.213231Search in Google Scholar PubMed PubMed Central
7. Hashimoto G, Inoki I, Fujii Y, Aoki T, Ikeda E, Okada Y. Matrix metalloproteinases cleave connective tissue growth factor and reactivate angiogenic activity of vascular endothelial growth factor 165. J Biol Chem 2002; 277: 36288–95.10.1074/jbc.M201674200Search in Google Scholar PubMed
8. Mochizuki S, Tanaka R, Shimoda M, Onuma J, Fujii Y, Jinno H, Okada Y. Connective tissue growth factor is a substrate of ADAM28. Biochem Biophys Res Commun 2010; 402: 651–7.10.1016/j.bbrc.2010.10.077Search in Google Scholar PubMed
9. Yanagita T, Kubota S, Kawaki H, Kawata K, Kondo S, Takano-Yamamoto T, Tanaka S, Takigawa M. Expression and physiological role of CCN4/Wnt-induced secreted protein 1 mRNA splicing variants in chondrocytes. FEBS J 2007; 274: 1655–65.10.1111/j.1742-4658.2007.05709.xSearch in Google Scholar PubMed
10. Mosher DF, Adams JC. Adhesion-modulating/matricellular ECM protein families: a structural, functional and evolutionary appraisal. Matrix Biol 2012; 31: 155–61.10.1016/j.matbio.2012.01.003Search in Google Scholar PubMed
11. Holbourn KP, Malfois M, Acharya KR. First structural glimpse of CCN3 and CCN5 multifunctional signaling regulators elucidated by small angle x-ray scattering. J Biol Chem 2011; 286: 22243–9.10.1074/jbc.M111.225755Search in Google Scholar PubMed PubMed Central
12. Hoshijima M, Hattori T, Aoyama E, Nishida T, Yamashiro T, Takigawa M. Roles of heterotypic CCN2/CTGF-CCN3/NOV and homotypic CCN2-CCN2 interactions in expression of the differentiated phenotype of chondrocytes. FEBS J 2012; 279: 3584–97.10.1111/j.1742-4658.2012.08717.xSearch in Google Scholar PubMed
13. Lin J, Zhou Z, Huo R, Xiao L, Ouyang G, Wang L, Sun Y, Shen B, Li D, Li N. Cyr61 induces IL-6 production by fibroblast-like synoviocytes promoting Th17 differentiation in rheumatoid arthritis. J Immunol 2012; 188: 5776–84.10.4049/jimmunol.1103201Search in Google Scholar PubMed
14. Gao R, Brigstock DR. Connective tissue growth factor (CCN2) induces adhesion of rat activated hepatic stellate cells by binding of its C-terminal domain to integrin α(v)β(3) and heparan sulfate proteoglycan. J Biol Chem 2004; 279: 8848–55.10.1074/jbc.M313204200Search in Google Scholar PubMed
15. Juric V, Chen CC, Lau LF. TNFα-induced apoptosis enabled by CCN1/CYR61: pathways of reactive oxygen species generation and cytochrome c release. PLoS One 2012; 7: e31303.10.1371/journal.pone.0031303Search in Google Scholar PubMed PubMed Central
16. Francischetti IM, Kotsyfakis M, Andersen JF, Lukszo J. Cyr61/CCN1 displays high-affinity binding to the somatomedin B(1-44) domain of vitronectin. PLoS One 2010; 5: e9356.10.1371/journal.pone.0009356Search in Google Scholar PubMed PubMed Central
17. Craig TA, Bhattacharya R, Mukhopadhyay D, Kumar R. Sclerostin binds and regulates the activity of cysteine-rich protein 61. Biochem Biophys Res Commun 2010; 392: 36–40.10.1016/j.bbrc.2009.12.143Search in Google Scholar PubMed PubMed Central
18. Liu SC, Hsu CJ, Chen HT, Tsou HK, Chuang SM, Tang CH. CTGF increases IL-6 expression in human synovial fibroblasts through integrin-dependent signaling pathway. PLoS One 2012; 7: e51097.10.1371/journal.pone.0051097Search in Google Scholar PubMed PubMed Central
19. Kawata K, Kubota S, Eguchi T, Aoyama E, Moritani NH, Kondo S, Nishida T, Takigawa M. Role of LRP1 in transport of CCN2 protein in chondrocytes. J Cell Sci 2012; 125: 2965–72.Search in Google Scholar
20. Aoyama E, Hattori T, Hoshijima M, Araki D, Nishida T, Kubota S, Takigawa M. N-terminal domains of CCN family 2/connective tissue growth factor bind to aggrecan. Biochem J 2009; 420: 413–20.10.1042/BJ20081991Search in Google Scholar PubMed
21. Kubota S, Takigawa M. The role of CCN2 in cartilage and bone development. J Cell Commun Signal 2011; 5: 209–17.10.1007/s12079-011-0123-5Search in Google Scholar PubMed PubMed Central
22. Aoyama E, Kubota S, Nishida T, Takigawa M. A novel role of CCN2 in RANK/RANKL/OPG signaling. J Dent Res 2013; 92: Special issue A: 1329.Search in Google Scholar
23. Rooney B, O’Donovan H, Gaffney A, Browne M, Faherty N, Curran SP, Sadlier D, Godson C, Brazil DP, Crean J. CTGF/CCN2 activates canonical Wnt signalling in mesangial cells through LRP6: implications for the pathogenesis of diabetic nephropathy. FEBS Lett 2011; 585: 531–8.10.1016/j.febslet.2011.01.004Search in Google Scholar PubMed
24. Ren S, Johnson BG, Kida Y, Ip C, Davidson KC, Lin SL, Kobayashi A, Lang RA, Hadjantonakis AK, Moon RT, Duffield JS. LRP-6 is a coreceptor for multiple fibrogenic signaling pathways in pericytes and myofibroblasts that are inhibited by DKK-1. Proc Natl Acad Sci USA 2013; 110: 1440–5.10.1073/pnas.1211179110Search in Google Scholar PubMed PubMed Central
25. Fragiadaki M, Hill N, Hewitt R, Bou-Gharios G, Cook T, Tam FW, Domin J, Mason RM. Hyperglycemia causes renal cell damage via CCN2-induced activation of the TrkA receptor. Diabetes 2012; 61: 2280–8.10.2337/db11-1138Search in Google Scholar PubMed PubMed Central
26. Aoyama E, Kubota S, Takigawa M. CCN2/CTGF binds to fibroblast growth factor receptor 2 and modulates its signaling. FEBS Lett 2012; 586: 4270–5.10.1016/j.febslet.2012.10.038Search in Google Scholar PubMed
27. Maeda A, Nishida T, Aoyama E, Kubota S, Lyons KM, Kuboki T, Takigawa M. CCN family 2/connective tissue growth factor modulates BMP signalling as a signal conductor, which action regulates the proliferation and differentiation of chondrocytes. J Biochem 2009; 145: 207–16.10.1093/jb/mvn159Search in Google Scholar PubMed PubMed Central
28. Nishida T, Kubota S, Aoyama E, Janune D, Maeda A, Takigawa M. Effect of CCN2 on FGF2-induced proliferation and MMP9 and MMP13 productions by chondrocytes. Endocrinology 2011; 182: 4232–41.10.1210/en.2011-0234Search in Google Scholar PubMed
29. Pi L, Shenoy AK, Liu J, Kim S, Nelson N, Xia H, Hauswirth WW, Petersen BE, Schultz GS, Scott EW. CCN2/CTGF regulates neovessel formation via targeting structurally conserved cystine knot motifs in multiple angiogenic regulators. FASEB J 2012; 26: 3365–79.10.1096/fj.11-200154Search in Google Scholar PubMed PubMed Central
30. Surmann-Schmitt C, Sasaki T, Hattori T, Eitzinger N, Schett G, von der Mark K, Stock M. The Wnt antagonist Wif-1 interacts with CTGF and inhibits CTGF activity. J Cell Physiol 2012; 227: 2207–16.10.1002/jcp.22957Search in Google Scholar PubMed
31. Hou CH, Tang CH, Hsu CJ, Hou SM, Liu JF. CCN4 induces IL-6 production through αvβ5 receptor, PI3K, Akt, and NF-κB singling pathway in human synovial fibroblasts. Arthritis Res Ther 2013; 15: R19.10.1186/ar4151Search in Google Scholar PubMed PubMed Central
32. Ohkawa Y, Ohmi Y, Tajima O, Yamauchi Y, Furukawa K, Furukawa K. Wisp2/CCN5 up-regulated in the central nervous system of GM3-only mice facilitates neurite formation in Neuro2a cells via integrin-Akt signaling. Biochem Biophys Res Commun 2011; 411: 483–9.10.1016/j.bbrc.2011.06.118Search in Google Scholar PubMed
33. Fong YC, Lin CY, Su YC, Chen WC, Tsai FJ, Tsai CH, Huang CY, Tang CH. CCN6 enhances ICAM-1 expression and cell motility in human chondrosarcoma cells. J Cell Physiol 2012; 227: 223–32.10.1002/jcp.22720Search in Google Scholar PubMed
34. Ono M, Inkson CA, Kilts TM, Young MF. WISP-1/CCN4 regulates osteogenesis by enhancing BMP-2 activity. J Bone Miner Res 2011; 26: 193–208.10.1002/jbmr.205Search in Google Scholar PubMed PubMed Central
35. Pal A, Huang W, Li X, Toy KA, Nikolovska-Coleska Z, Kleer CG. CCN6 modulates BMP signaling via the Smad-independent TAK1/p38 pathway, acting to suppress metastasis of breast cancer. Cancer Res 2012; 72: 4818–28.10.1158/0008-5472.CAN-12-0154Search in Google Scholar PubMed PubMed Central
36. Nakamura Y, Weidinger G, Liang JO, Aquilina-Beck A, Tamai K, Moon RT, Warman ML. The CCN family member Wisp3, mutant in progressive pseudorheumatoid dysplasia, modulates BMP and Wnt signaling. J Clin Invest 2007; 117: 3075–86.10.1172/JCI32001Search in Google Scholar PubMed PubMed Central
37. Repudi SR, Patra M, Sen M. WISP3-IGF1 interaction regulates chondrocyte hypertrophy. J Cell Sci 2013; 126: 1650–8.Search in Google Scholar
38. Kubota S, Takigawa M. CCN. In: Choi S, editor. Encyclopedia of signaling molecules. Dordrecht, Netherlands: Springer, 2012: 273–81.Search in Google Scholar
39. Kular L, Pakradouni J, Kitabgi P, Laurent M, Martinerie C. The CCN family: a new class of inflammation modulators? Biochimie 2011; 93: 377–88.10.1016/j.biochi.2010.11.010Search in Google Scholar PubMed
40. Moritani NH, Kubota S, Sugahara T, Takigawa M. Comparable response of ccn1 with ccn2 genes upon arthritis: an in vitro evaluation with a human chondrocytic cell line stimulated by a set of cytokines. Cell Commun Signal 2005; 3: 6.10.1186/1478-811X-3-6Search in Google Scholar PubMed PubMed Central
41. Ferrand N, Stragier E, Redeuilh G, Sabbah M. Glucocorticoids induce CCN5/WISP-2 expression and attenuate invasion in oestrogen receptor-negative human breast cancer cells. Biochem J 2012; 447: 71–9.10.1042/BJ20120311Search in Google Scholar PubMed
42. Okada H, Kikuta T, Inoue T, Kanno Y, Ban S, Sugaya T, Takigawa M, Suzuki H. Dexamethasone induces connective tissue growth factor expression in renal tubular epithelial cells in a mouse strain-specific manner. Am J Pathol 2006; 168: 737–47.10.2353/ajpath.2006.050656Search in Google Scholar PubMed PubMed Central
43. Liao HJ, de Los Santos J, Carpenter G. Contrasting role of phospholipase C-γ1 in the expression of immediate early genes induced by epidermal or platelet-derived growth factors. Exp Cell Res 2006; 312: 807–16.10.1016/j.yexcr.2005.11.034Search in Google Scholar PubMed
44. Koon HW, Shih DQ, Hing TC, Chen J, Ho S, Zhao D, Targan SR, Pothoulakis C. Substance P induces CCN1 expression via histone deacetylase activity in human colonic epithelial cells. Am J Pathol 2011; 179: 2315–26.10.1016/j.ajpath.2011.07.038Search in Google Scholar PubMed PubMed Central
45. Espinoza I, Liu H, Busby R, Lupu R. CCN1, a candidate target for zoledronic acid treatment in breast cancer. Mol Cancer Ther 2011; 10: 732–41.10.1158/1535-7163.MCT-10-0836Search in Google Scholar PubMed PubMed Central
46. Kim JN, Kim HJ, Jeong SH, Kye YC, Son SW. Cigarette smoke-induced early growth response-1 regulates the expression of the cysteine-rich 61 in human skin dermal fibroblasts. Exp Dermatol 2011; 20: 992–7.10.1111/j.1600-0625.2011.01380.xSearch in Google Scholar PubMed
47. Gu J, Liu X, Wang QX, Tan HW, Guo M, Jiang WF, Zhou L. Angiotensin II increases CTGF expression via MAPKs/TGF-β1/TRAF6 pathway in atrial fibroblasts. Exp Cell Res 2012; 318: 2105–15.10.1016/j.yexcr.2012.06.015Search in Google Scholar PubMed
48. Alfaro MP, Deskins DL, Wallus M, DasGupta J, Davidson JM, Nanney LB, A Guney M, Gannon M, Young PP. A physiological role for connective tissue growth factor in early wound healing. Lab Invest 2013; 93: 81–95.10.1038/labinvest.2012.162Search in Google Scholar PubMed PubMed Central
49. Matika CA, Wasilewski M, Arnott JA, Planey SL. Antiproliferative factor regulates connective tissue growth factor (CTGF/CCN2) expression in T24 bladder carcinoma cells. Mol Biol Cell 2012; 23: 1976–85.10.1091/mbc.e11-08-0714Search in Google Scholar PubMed PubMed Central
50. Bai KJ, Chen BC, Pai HC, Weng CM, Yu CC, Hsu MJ, Yu MC, Ma HP, Wu CH, Hong CY, Kuo ML, Lin CH. Thrombin-induced CCN2 expression in human lung fibroblasts requires the c-Src/JAK2/STAT3 pathway. J Leukoc Biol 2013; 93: 101–12.10.1189/jlb.0911449Search in Google Scholar PubMed
51. Laug R, Fehrholz M, Schütze N, Kramer BW, Krump-Konvalinkova V, Speer CP, Kunzmann S. IFN-γ and TNF-α synergize to inhibit CTGF expression in human lung endothelial cells. PLoS One 2012; 7: e45430.10.1371/journal.pone.0045430Search in Google Scholar PubMed PubMed Central
52. Chen YW, Yang WH, Wong MY, Chang HH, Yen-Ping Kuo M. Curcumin inhibits thrombin-stimulated connective tissue growth factor (CTGF/CCN2) production through c-Jun NH2-terminal kinase suppression in human gingival fibroblasts. J Periodontol 2012; 83: 1546–53.10.1902/jop.2012.110641Search in Google Scholar PubMed
53. Yang WH, Kuo MY, Liu CM, Deng YT, Chang HH, Chang JZ. Curcumin inhibits TGFβ1-induced CCN2 via Src, JNK, and Smad3 in gingiva. J Dent Res 2013; 92: 629–34.10.1177/0022034513488139Search in Google Scholar PubMed
54. Takeuchi H, Kubota S, Murakashi E, Zhou Y, Endo K, Ng PS, Takigawa M, Numabe Y. Nicotine-induced CCN2: from smoking to periodontal fibrosis. J Dent Res 2010; 89: 34–9.10.1177/0022034509353403Search in Google Scholar PubMed
55. Wang R, Xu YJ, Liu XS, Zeng DX, Xiang M. CCN2 promotes cigarette smoke-induced proliferation of rat pulmonary artery smooth muscle cells through upregulating cyclin D1 expression. J Cell Biochem 2012; 113: 349–59.10.1002/jcb.23361Search in Google Scholar PubMed
56. Eguchi T, Kubota S, Kawata K, Mukudai Y, Uehara J, Ohgawara T, Ibaragi S, Sasaki A, Kuboki T, Takigawa M. Novel transcription-factor-like function of human matrix metalloproteinase 3 regulating the CTGF/CCN2 gene. Mol Cell Biol 2008; 28: 2391–413.10.1128/MCB.01288-07Search in Google Scholar PubMed PubMed Central
57. Muromachi K, Kamio N, Narita T, Annen-Kamio M, Sugiya H, Matsushima K. MMP-3 provokes CTGF/CCN2 production independently of protease activity and dependently on dynamin-related endocytosis, which contributes to human dental pulp cell migration. J Cell Biochem 2012; 113: 1348–58.10.1002/jcb.24007Search in Google Scholar PubMed
58. Kimura A, Martin C, Robinson GW, Simone JM, Chen W, Wickre MC, O’Shea JJ, Hennighausen L. The gene encoding the hematopoietic stem cell regulator CCN3/NOV is under direct cytokine control through the transcription factors STAT5A/B. J Biol Chem 2010; 285: 32704–9.10.1074/jbc.M110.141804Search in Google Scholar PubMed PubMed Central
59. Liu ZJ, Li Y, Tan Y, Xiao M, Zhang J, Radtke F, Velazquez OC. Inhibition of fibroblast growth by Notch1 signaling is mediated by induction of Wnt11-dependent WISP-1. PLoS One 2012; 7: e38811.10.1371/journal.pone.0038811Search in Google Scholar PubMed PubMed Central
60. Wang H, Zhang R, Wen S, McCafferty DM, Beck PL, MacNaughton WK. Nitric oxide increases Wnt-induced secreted protein-1 (WISP-1/CCN4) expression and function in colitis. J Mol Med (Berl) 2009; 87: 435–45.10.1007/s00109-009-0445-4Search in Google Scholar PubMed
61. Hennemeier I, Humpf HU, Gekle M, Schwerdt G. The food contaminant and nephrotoxin ochratoxin A enhances Wnt1 inducible signaling protein 1 and tumor necrosis factor-α expression in human primary proximal tubule cells. Mol Nutr Food Res 2012; 56: 1375–84.10.1002/mnfr.201200164Search in Google Scholar PubMed
62. Dhar K, Banerjee S, Dhar G, Sengupta K, Banerjee SK. Insulin-like growth factor-1 (IGF-1) induces WISP-2/CCN5 via multiple molecular cross-talks and is essential for mitogenic switch by IGF-1 axis in estrogen receptor-positive breast tumor cells. Cancer Res 2007; 67: 1520–6.10.1158/0008-5472.CAN-06-3753Search in Google Scholar PubMed
63. Chaqour B, Goppelt-Struebe M. Mechanical regulation of the Cyr61/CCN1 and CTGF/CCN2 proteins. FEBS J 2006; 273: 3639–49.10.1111/j.1742-4658.2006.05360.xSearch in Google Scholar PubMed
64. Honjo T, Kubota S, Kamioka H, Sugawara Y, Ishihara Y, Yamashiro T, Takigawa M, Takano-Yamamoto T. Promotion of Ccn2 expression and osteoblastic differentiation by actin polymerization, which is induced by laminar fluid flow stress. J Cell Commun Signal 2012; 6: 225–32.10.1007/s12079-012-0177-zSearch in Google Scholar PubMed PubMed Central
65. Shiraishi R, Masaki C, Toshinaga A, Okinaga T, Nishihara T, Yamanaka N, Nakamoto T, Hosokawa R. The effects of low-intensity pulsed ultrasound exposure on gingival cells. J Periodontol 2011; 82: 1498–503.10.1902/jop.2011.100627Search in Google Scholar PubMed
66. Geisinger MT, Astaiza R, Butler T, Popoff SN, Planey SL, Arnott JA. Ets-1 is essential for connective tissue growth factor (CTGF/CCN2) induction by TGF-β1 in osteoblasts. PLoS One 2012; 7: e35258.10.1371/journal.pone.0035258Search in Google Scholar PubMed PubMed Central
67. Kodama T, Takehara T, Hikita H, Shimizu S, Shigekawa M, Tsunematsu H, Li W, Miyagi T, Hosui A, Tatsumi T, Ishida H, Kanto T, Hiramatsu N, Kubota S, Takigawa M, Tomimaru Y, Tomokuni A, Nagano H, Doki Y, Mori M, Hayashi N. Increases in p53 expression induce CTGF synthesis by mouse and human hepatocytes and result in liver fibrosis in mice. J Clin Invest 2011; 121: 3343–56.10.1172/JCI44957Search in Google Scholar PubMed PubMed Central
68. Samarin J, Wessel J, Cicha I, Kroening S, Warnecke C, Goppelt-Struebe M. FoxO proteins mediate hypoxic induction of connective tissue growth factor in endothelial cells. J Biol Chem 2010; 285: 4328–36.10.1074/jbc.M109.049650Search in Google Scholar PubMed PubMed Central
69. Lai D, Ho KC, Hao Y, Yang X. Taxol resistance in breast cancer cells is mediated by the hippo pathway component TAZ and its downstream transcriptional targets Cyr61 and CTGF. Cancer Res 2011; 71: 2728–38.10.1158/0008-5472.CAN-10-2711Search in Google Scholar PubMed
70. Dhar G, Banerjee S, Dhar K, Tawfik O, Mayo MS, Vanveldhuizen PJ, Banerjee SK. Gain of oncogenic function of p53 mutants induces invasive phenotypes in human breast cancer cells by silencing CCN5/WISP-2. Cancer Res 2008; 68: 4580–7.10.1158/0008-5472.CAN-08-0316Search in Google Scholar PubMed
71. Zhang Y, Wang C. Nephroblastoma overexpressed (NOV/CCN3) gene: a paired-domain-specific PAX3-FKHR transcription target that promotes survival and motility in alveolar rhabdomyosarcoma cells. Oncogene 2011; 30: 3549–62.10.1038/onc.2011.69Search in Google Scholar PubMed PubMed Central
72. Kubota S, Kondo S, Eguchi T, Hattori T, Nakanishi T, Pomerantz RJ, Takigawa M. Identification of an RNA element that confers post-transcriptional repression of connective tissue growth factor/hypertrophic chondrocyte specific 24 (ctgf/hcs24) gene: similarities to retroviral RNA-protein interactions. Oncogene 2000; 19: 4773–86.10.1038/sj.onc.1203835Search in Google Scholar PubMed
73. Kondo S, Kubota S, Mukudai Y, Nishida T, Yoshihama Y, Shirota T, Shintani S, Takigawa M. Binding of glyceraldehyde-3-phosphate dehydrogenase to the cis-acting element of structure-anchored repression in ccn2 mRNA. Biochem Biophys Res Commun 2011; 405: 382–7.10.1016/j.bbrc.2011.01.034Search in Google Scholar PubMed
74. Kondo S, Kubota S, Eguchi T, Hattori T, Nakanishi T, Sugahara T, Takigawa M. Characterization of a mouse ctgf 3’-UTR segment that mediates repressive regulation of gene expression. Biochem Biophys Res Commun 2000; 278: 119–24.10.1006/bbrc.2000.3780Search in Google Scholar PubMed
75. Mukudai Y, Kubota S, Kawaki H, Kondo S, Eguchi T, Sumiyoshi K, Ohgawara T, Shimo T, Takigawa M. Posttranscriptional regulation of chicken ccn2 gene expression by nucleophosmin/B23 during chondrocyte differentiation. Mol Cell Biol 2008; 28: 6134–47.10.1128/MCB.00495-08Search in Google Scholar PubMed PubMed Central
76. Ohgawara T, Kubota S, Kawaki H, Kondo S, Eguchi T, Kurio N, Aoyama E, Sasaki A, Takigawa M. Regulation of chondrocytic phenotype by micro RNA 18a: involvement of Ccn2/Ctgf as a major target gene. FEBS Lett 2009; 583: 1006–10.10.1016/j.febslet.2009.02.025Search in Google Scholar
77. Lee HK, Bier A, Cazacu S, Finniss S, Xiang C, Twito H, Poisson LM, Mikkelsen T, Slavin S, Jacoby E, Yalon M, Toren A, Rempel SA, Brodie C. MicroRNA-145 is downregulated in glial tumors and regulates glioma cell migration by targeting connective tissue growth factor. PLoS One 2013; 8: e54652.10.1371/journal.pone.0054652Search in Google Scholar
78. Nakagawa Y, Minato M, Sumiyoshi K, Maeda A, Hara C, Murase Y, Nishida T, Kubota S, Takigawa M. Regulation of CCN1 via the 3’-untranslated region. J Cell Commun Signal 2013; 7: 207–1710.1007/s12079-013-0202-xSearch in Google Scholar
79. Mukudai Y, Kubota S, Eguchi T, Sumiyoshi K, Janune D, Kondo S, Shintani S, Takigawa M. A coding RNA segment that enhances the ribosomal recruitment of chicken ccn1 mRNA. J Cell Biochem 2010; 111: 1607–18.10.1002/jcb.22894Search in Google Scholar
80. Sumiyoshi K, Kubota S, Ohgawara T, Kawata K, Kader TA, Nishida T, Ikeda N, Shimo T, Yamashiro T, Takigawa M. Novel role of miR-181a in cartilage metabolism. J Cell Biochem 2013; 114: 2094–100.10.1002/jcb.24556Search in Google Scholar
81. Sabbah M, Prunier C, Ferrand N, Megalophonos V, Lambein K, De Wever O, Nazaret N, Lachuer J, Dumont S, Redeuilh G. CCN5, a novel transcriptional repressor of the transforming growth factor β signaling pathway. Mol Cell Biol 2011; 31: 1459–69.10.1128/MCB.01316-10Search in Google Scholar
82. Kubota S, Takigawa M. Role of CCN2/CTGF/Hcs24 in bone growth. Int Rev Cytol 2007; 257: 1–41.10.1016/S0074-7696(07)57001-4Search in Google Scholar
83. Takigawa M. CCN2: A master regulator of the genesis of bone and cartilage. J Cell Commun Signal 2013; 7: 191 –201.10.1007/s12079-013-0204-8Search in Google Scholar PubMed PubMed Central
84. Kawaki H, Kubota S, Suzuki A, Lazar N, Yamada T, Matsumura T, Ohgawara T, Maeda T, Perbal B, Lyons KM, Takigawa M. Cooperative regulation of chondrocyte differentiation by CCN2 and CCN3 shown by a comprehensive analysis of the CCN family proteins in cartilage. J Bone Miner Res 2008; 23: 1751–64.10.1359/jbmr.080615Search in Google Scholar PubMed PubMed Central
85. Ivkovic S, Yoon BS, Popoff SN, Safadi FF, Libuda DE, Stephenson RC, Daluiski A, Lyons KM. Connective tissue growth factor coordinates chondrogenesis and angiogenesis during skeletal development. Development 2003; 130: 2779–91.10.1242/dev.00505Search in Google Scholar PubMed PubMed Central
86. Nishida T, Kubota S, Kojima S, Kuboki T, Nakao K, Kushibiki T, Tabata Y, Takigawa M. Regeneration of defects in articular cartilage in rat knee joints by CCN2 (connective tissue growth factor). J Bone Miner Res 2004; 19: 1308–19.10.1359/JBMR.040322Search in Google Scholar PubMed
87. Kikuchi T, Kubota S, Asaumi K, Kawaki H, Nishida T, Kawata K, Mitani S, Tabata Y, Ozaki T, Takigawa M. Promotion of bone regeneration by CCN2 incorporated into gelatin hydrogel. Tissue Eng Part A 2008; 14: 1089–98.10.1089/ten.tea.2007.0167Search in Google Scholar
88. Kawaki H, Kubota S, Suzuki A, Suzuki M, Kohsaka K, Hoshi K, Fujii T, Lazar N, Ohgawara T, Maeda T, Perbal B, Takano-Yamamoto T, Takigawa M. Differential roles of CCN family proteins during osteoblast differentiation: involvement of Smad and MAPK signaling pathways. Bone 2011; 49: 975–9.10.1016/j.bone.2011.06.033Search in Google Scholar PubMed
89. Lafont J, Jacques C, Le Dreau G, Calhabeu F, Thibout H, Dubois C, Berenbaum F, Laurent M, Martinerie C. New target genes for NOV/CCN3 in chondrocytes: TGF-beta2 and type X collagen. J Bone Miner Res 2005; 20: 2213–23.10.1359/JBMR.050818Search in Google Scholar PubMed
90. Matsushita Y, Sakamoto K, Tamamura Y, Shibata Y, Minamizato T, Kihara T, Ito M, Katsube KI, Hiraoka S, Koseki H, Harada K, Yamaguchi A. CCN3 participates in bone regeneration as an inhibitory factor. J Biol Chem 2013; 288: 19973–85.10.1074/jbc.M113.454652Search in Google Scholar PubMed PubMed Central
91. Janune D, Kubota S, Nishida T, Kawaki H, Perbal B, Iida S, Takigawa M. Novel effects of CCN3 that may direct the differentiation of chondrocytes. FEBS Lett 2011; 885: 3033–40.10.1016/j.febslet.2011.08.024Search in Google Scholar PubMed
92. Heath E, Tahri D, Andermarcher E, Schofield P, Fleming S, Boulter CA. Abnormal skeletal and cardiac development, cardiomyopathy, muscle atrophy and cataracts in mice with a targeted disruption of the Nov (Ccn3) gene. Dev Biol 2008; 8: 18.10.1186/1471-213X-8-18Search in Google Scholar PubMed PubMed Central
93. Sun J, Xia W, He S, Zhao Z, Nie M, Li M, Jiang Y, Xing X, Wang O, Meng X, Zhou X. Novel and recurrent mutations of WISP3 in two Chinese families with progressive pseudorheumatoid dysplasia. PLoS One 2012; 7: e38643.10.1371/journal.pone.0038643Search in Google Scholar PubMed PubMed Central
94. Gelse K, Ekici AB, Cipa F, Swoboda B, Carl HD, Olk A, Hennig FF, Klinger P. Molecular differentiation between osteophytic and articular cartilage – clues for a transient and permanent chondrocyte phenotype. Osteoarthritis Cartilage 2012; 20: 162–71.10.1016/j.joca.2011.12.004Search in Google Scholar PubMed
95. Cui RR, Huang J, Yi L, Xie H, Zhou HD, Yuan LQ, Wang M, Peng YQ, Luo XH, Liao EY. WISP3 suppresses insulin-like growth factor signaling in human chondrocytes. Mol Cell Endocrinol 2007; 279: 1–8.10.1016/j.mce.2007.08.007Search in Google Scholar PubMed
96. Mo FE, Lau LF. The matricellular protein CCN1 is essential for cardiac development. Circ Res 2006; 99: 961–9.10.1161/01.RES.0000248426.35019.89Search in Google Scholar PubMed PubMed Central
97. Mo FE, Muntean AG, Chen CC, Stolz DB, Watkins SC, Lau LF. CYR61 (CCN1) is essential for placental development and vascular integrity. Mol Cell Biol 2002; 22: 8709–20.10.1128/MCB.22.24.8709-8720.2002Search in Google Scholar PubMed PubMed Central
98. Kondo S, Kubota S, Mukudai Y, Moritani N, Nishida T, Matsushita H, Matsumoto S, Sugahara T, Takigawa M. Hypoxic regulation of stability of connective tissue growth factor/CCN2 mRNA by 3’-untranslated region interacting with a cellular protein in human chondrosarcoma cells. Oncogene 2006; 25: 1099–110.10.1038/sj.onc.1209129Search in Google Scholar PubMed
99. Shimo T, Kubota S, Yoshioka N, Ibaragi S, Isowa S, Eguchi T, Sasaki A, Takigawa M. Pathogenic role of connective tissue growth factor (CTGF/CCN2) in osteolytic metastasis of breast cancer. J Bone Miner Res 2006; 21: 1045–59.10.1359/jbmr.060416Search in Google Scholar PubMed
100. Lorenzatti G, Huang W, Pal A, Cabanillas AM, Kleer CG. CCN6 (WISP3) decreases ZEB1-mediated EMT and invasion by attenuation of IGF-1 receptor signaling in breast cancer. J Cell Sci 2011; 124: 1752–8.10.1242/jcs.084194Search in Google Scholar PubMed PubMed Central
101. Huang W, Pal A, Kleer CG. On how CCN6 suppresses breast cancer growth and invasion. J Cell Commun Signal 2012; 6: 5–10.10.1007/s12079-011-0148-9Search in Google Scholar PubMed PubMed Central
102. Shimoyama T, Hiraoka S, Takemoto M, Koshizaka M, Tokuyama H, Tokuyama T, Watanabe A, Fujimoto M, Kawamura H, Sato S, Tsurutani Y, Saito Y, Perbal B, Koseki H, Yokote K. CCN3 inhibits neointimal hyperplasia through modulation of smooth muscle cell growth and migration. Arterioscler Thromb Vasc Biol 2010; 30: 675–82.10.1161/ATVBAHA.110.203356Search in Google Scholar PubMed
103. Koitabashi N, Arai M, Niwano K, Watanabe A, Endoh M, Suguta M, Yokoyama T, Tada H, Toyama T, Adachi H, Naito S, Oshima S, Nishida T, Kubota S, Takigawa M, Kurabayashi M. Plasma connective tissue growth factor is a novel potential biomarker of cardiac dysfunction in patients with chronic heart failure. Eur J Heart Fail 2008; 10: 373–9.10.1016/j.ejheart.2008.02.011Search in Google Scholar PubMed
104. Colston JT, de la Rosa SD, Koehler M, Gonzales K, Mestril R, Freeman GL, Bailey SR, Chandrasekar B. Wnt-induced secreted protein-1 is a prohypertrophic and profibrotic growth factor. Am J Physiol Heart Circ Physiol 2007; 293: H1839–46.10.1152/ajpheart.00428.2007Search in Google Scholar PubMed
105. Gravning J, Ahmed MS, von Lueder TG, Edvardsen T, Attramadal H. CCN2/CTGF attenuates myocardial hypertrophy and cardiac dysfunction upon chronic pressure-overload. Int J Cardiol. 2013. in press.10.1016/j.ijcard.2013.01.165Search in Google Scholar PubMed
106. Sumiyoshi K, Kubota S, Furuta RA, Yasui K, Aoyama E, Kawaki H, Kawata K, Ohgawara T, Yamashiro T, Takigawa M. Thrombopoietic-mesenchymal interaction that may facilitate both endochondral ossification and platelet maturation via CCN2. J Cell Commun Signal 2010; 4: 5–14.10.1007/s12079-009-0067-1Search in Google Scholar
107. Gupta R, Hong D, Iborra F, Sarno S, Enver T. NOV (CCN3) functions as a regulator of human hematopoietic stem or progenitor cells. Science 2007; 316: 590–3.10.1126/science.1136031Search in Google Scholar
108. McCallum L, Irvine AE. CCN3—a key regulator of the hematopoietic compartment. Blood Rev 2009; 23: 79–85.10.1016/j.blre.2008.07.002Search in Google Scholar
109. Kondo Y, Nakanishi T, Takigawa M, Ogawa N. Immunohistochemical localization of connective tissue growth factor in the rat central nervous system. Brain Res 1999; 834: 146–51.10.1016/S0006-8993(99)01517-6Search in Google Scholar
110. Nawachi K, Inoue M, Kubota S, Nishida T, Yosimichi G, Nakanishi T, Kanyama M, Kuboki T, Yatani H, Yamaai T, Takigawa M. Tyrosine kinase-type receptor ErbB4 in chondrocytes: interaction with connective tissue growth factor and distribution in cartilage. FEBS Lett 2002; 528: 109–13.10.1016/S0014-5793(02)03263-5Search in Google Scholar
111. Malik AR, Urbanska M, Gozdz A, Swiech LJ, Nagalski A, Perycz M, Blazejczyk M, Jaworski J. Cyr61, a matricellular protein, is needed for dendritic arborization of hippocampal neurons. J Biol Chem 2013; 288: 8544–59.10.1074/jbc.M112.411629Search in Google Scholar PubMed PubMed Central
112. Zhao Z, Ho L, Wang J, Qin W, Festa ED, Mobbs C, Hof P, Rocher A, Masur S, Haroutunian V, Pasinetti GM. Connective tissue growth factor (CTGF) expression in the brain is a downstream effector of insulin resistance-associated promotion of Alzheimer’s disease beta-amyloid neuropathology. FASEB J 2005; 19: 2081–2.10.1096/fj.05-4359fjeSearch in Google Scholar PubMed
113. Le Dréau G, Nicot A, Bénard M, Thibout H, Vaudry D, Martinerie C, Laurent M. NOV/CCN3 promotes maturation of cerebellar granule neuron precursors. Mol Cell Neurosci 2010; 43: 60–71.10.1016/j.mcn.2009.02.011Search in Google Scholar PubMed
114. Shang YC, Chong ZZ, Wang S, Maiese K. Tuberous sclerosis protein 2 (TSC2) modulates CCN4 cytoprotection during apoptotic amyloid toxicity in microglia. Curr Neurovasc Res 2013; 10: 29–38.10.2174/156720213804806007Search in Google Scholar PubMed PubMed Central
115. Charrier A, Brigstock DR. Regulation of pancreatic function by connective tissue growth factor (CTGF, CCN2). Cytokine Growth Factor Rev 2013; 24: 59–68.10.1016/j.cytogfr.2012.07.001Search in Google Scholar PubMed PubMed Central
116. Yan L, Chaqour B. Cysteine-rich protein 61 (CCN1) and connective tissue growth factor (CCN2) at the crosshairs of ocular neovascular and fibrovascular disease therapy. J Cell Commun Signal 2013. in press.10.1007/s12079-013-0206-6Search in Google Scholar PubMed PubMed Central
117. Maryvonne L, Gwenvaël le D, Xavier G, Cécile LE, Amélie S, Olivier G, Cécile M, Maria M. Temporal and spatial expression of CCN3 during retina development. Dev Neurobiol 2012; 72: 1363–75.10.1002/dneu.20994Search in Google Scholar PubMed
118. Kubota S. CCN2 in orofacial development and remodeling. Jpn Dent Sci Rev 2012; 48: 101–13.10.1016/j.jdsr.2012.02.002Search in Google Scholar
119. Abd El Kader T, Kubota S, Janune D, Nishida T, Hattori T, Aoyama E, Perbal B, Kuboki T, Takigawa M. Anti-fibrotic effect of CCN3 accompanied by altered gene expression profile of the CCN family. J Cell Commun Signal 2013; 7: 11–8.10.1007/s12079-012-0180-4Search in Google Scholar PubMed PubMed Central
120. Jun JI, Lau LF. The matricellular protein CCN1 induces fibroblast senescence and restricts fibrosis in cutaneous wound healing. Nat Cell Biol 2010; 12: 676–85.10.1038/ncb2070Search in Google Scholar PubMed PubMed Central
121. Sawai K, Mukoyama M, Mori K, Kasahara M, Koshikawa M, Yokoi H, Yoshioka T, Ogawa Y, Sugawara A, Nishiyama H, Yamada S, Kuwahara T, Saleem MA, Shiota K, Ogawa O, Miyazato M, Kangawa K, Nakao K. Expression of CCN1 (CYR61) in developing, normal, and diseased human kidney. Am J Physiol Renal Physiol 2007; 293: F1363–72.10.1152/ajprenal.00205.2007Search in Google Scholar PubMed
122. Phanish MK, Winn SK, Dockrell ME. Connective tissue growth factor-(CTGF, CCN2) – a marker, mediator and therapeutic target for renal fibrosis. Nephron Exp Nephrol 2010; 114: e83–92.10.1159/000262316Search in Google Scholar PubMed
123. Hasan A, Pokeza N, Shaw L, Lee HS, Lazzaro D, Chintala H, Rosenbaum D, Grant MB, Chaqour B. The matricellular protein cysteine-rich protein 61 (CCN1/Cyr61) enhances physiological adaptation of retinal vessels and reduces pathological neovascularization associated with ischemic retinopathy. J Biol Chem 2011; 286: 9542–54.10.1074/jbc.M110.198689Search in Google Scholar PubMed PubMed Central
124. Riser BL, Najmabadi F, Perbal B, Peterson DR, Rambow JA, Riser ML, Sukowski E, Yeger H, Riser SC. CCN3 (NOV) is a negative regulator of CCN2 (CTGF) and a novel endogenous inhibitor of the fibrotic pathway in an in vitro model of renal disease. Am J Pathol 2009; 174: 1725–34.10.2353/ajpath.2009.080241Search in Google Scholar PubMed PubMed Central
125. Königshoff M, Kramer M, Balsara N, Wilhelm J, Amarie OV, Jahn A, Rose F, Fink L, Seeger W, Schaefer L, Günther A, Eickelberg O. WNT1-inducible signaling protein-1 mediates pulmonary fibrosis in mice and is upregulated in humans with idiopathic pulmonary fibrosis. J Clin Invest 2009; 119: 772–87.10.1172/JCI33950Search in Google Scholar PubMed PubMed Central
126. Batmunkh R, Nishioka Y, Aono Y, Azuma M, Kinoshita K, Kishi J, Makino H, Kishi M, Takezaki A, Sone S. CCN6 as a profibrotic mediator that stimulates the proliferation of lung fibroblasts via the integrin β1/focal adhesion kinase pathway. J Med Invest 2011; 58: 188–96.10.2152/jmi.58.188Search in Google Scholar
127. Kim KH, Chen CC, Monzon RI, Lau LF. Matricellular protein CCN1 promotes regression of liver fibrosis through induction of cellular senescence in hepatic myofibroblasts. Mol Cell Biol 2013; 33: 2078–90.10.1128/MCB.00049-13Search in Google Scholar
128. Morales MG, Cabello-Verrugio C, Santander C, Cabrera D, Goldschmeding R, Brandan E. CTGF/CCN-2 over-expression can directly induce features of skeletal muscle dystrophy. J Pathol 2011; 225: 490–501.10.1002/path.2952Search in Google Scholar
129. Liu SC, Hsu CJ, Fong YC, Chuang SM, Tang CH. CTGF induces monocyte chemoattractant protein-1 expression to enhance monocyte migration in human synovial fibroblasts. Biochim Biophys Acta 2013; 1833: 1114–24.10.1016/j.bbamcr.2012.12.014Search in Google Scholar
130. Tan TW, Yang WH, Lin YT, Hsu SF, Li TM, Kao ST, Chen WC, Fong YC, Tang CH. Cyr61 increases migration and MMP-13 expression via αvβ3 integrin, FAK, ERK and AP-1-dependent pathway in human chondrosarcoma cells. Carcinogenesis 2009; 30: 258–68.10.1093/carcin/bgn284Search in Google Scholar
131. Kondo S, Kubota S, Shimo T, Nishida T, Yosimichi G, Eguchi T, Sugahara T, Takigawa M. Connective tissue growth factor increased by hypoxia may initiate angiogenesis in collaboration with matrix metalloproteinases. Carcinogenesis 2002; 23: 769–76.10.1093/carcin/23.5.769Search in Google Scholar
132. Tzeng HE, Chen JC, Tsai CH, Kuo CC, Hsu HC, Hwang WL, Fong YC, Tang CH. CCN3 increases cell motility and MMP-13 expression in human chondrosarcoma through integrin-dependent pathway. J Cell Physiol 2011; 226: 3181–9.10.1002/jcp.22672Search in Google Scholar
133. Soon LL, Yie TA, Shvarts A, Levine AJ, Su F, Tchou-Wong KM. Overexpression of WISP-1 down-regulated motility and invasion of lung cancer cells through inhibition of Rac activation. J Biol Chem 2003; 278: 11465–70.10.1074/jbc.M210945200Search in Google Scholar
134. Banerjee S, Dhar G, Haque I, Kambhampati S, Mehta S, Sengupta K, Tawfik O, Phillips TA, Banerjee SK. CCN5/WISP-2 expression in breast adenocarcinoma is associated with less frequent progression of the disease and suppresses the invasive phenotypes of tumor cells. Cancer Res 2008; 68: 7606–12.10.1158/0008-5472.CAN-08-1461Search in Google Scholar
135. Moritani NH, Kubota S, Nishida T, Kawaki H, Kondo S, Sugahara T, Takigawa M. Suppressive effect of overexpressed connective tissue growth factor on tumor cell growth in a human oral squamous cell carcinoma-derived cell line. Cancer Lett 2003; 192: 205–14.10.1016/S0304-3835(02)00718-8Search in Google Scholar
136. Chen PC, Cheng HC, Tang CH. CCN3 promotes prostate cancer bone metastasis by modulating the tumor-bone microenvironment through RANKL-dependent pathway. Carcinogenesis 2013; 34: 1669–79.10.1093/carcin/bgt103Search in Google Scholar PubMed
137. Jiang WG, Watkins G, Fodstad O, Douglas-Jones A, Mokbel K, Mansel RE. Differential expression of the CCN family members Cyr61, CTGF and Nov in human breast cancer. Endocr Relat Cancer 2004; 11: 781–91.10.1677/erc.1.00825Search in Google Scholar PubMed
138. Ouellet V, Tiedemann K, Mourskaia A, Fong JE, Tran-Thanh D, Amir E, Clemons M, Perbal B, Komarova SV, Siegel PM. CCN3 impairs osteoblast and stimulates osteoclast differentiation to favor breast cancer metastasis to bone. Am J Pathol 2011; 178: 2377–88.10.1016/j.ajpath.2011.01.033Search in Google Scholar PubMed PubMed Central
139. Chintala H, Liu H, Parmar R, Kamalska M, Kim YJ, Lovett D, Grant MB, Chaqour B. Connective tissue growth factor regulates retinal neovascularization through p53 protein-dependent transactivation of the matrix metalloproteinase (MMP)-2 gene. J Biol Chem 2012; 287: 40570–85.10.1074/jbc.M112.386565Search in Google Scholar PubMed PubMed Central
140. Inoki I, Shiomi T, Hashimoto G, Enomoto H, Nakamura H, Makino K, Ikeda E, Takata S, Kobayashi K, Okada Y. Connective tissue growth factor binds vascular endothelial growth factor (VEGF) and inhibits VEGF-induced angiogenesis. FASEB J 2002; 16: 219–21.10.1096/fj.01-0332fjeSearch in Google Scholar PubMed
141. Van Geest RJ, Klaassen I, Lesnik-Oberstein SY, Tan HS, Mura M, Goldschmeding R, Van Noorden CJ, Schlingemann RO. Vitreous TIMP-1 levels associate with neovascularization and TGF-β2 levels but not with fibrosis in the clinical course of proliferative diabetic retinopathy. J Cell Commun Signal 2013; 7: 1–9.10.1007/s12079-012-0178-ySearch in Google Scholar PubMed PubMed Central
142. Hinton DR, Spee C, He S, Weitz S, Usinger W, LaBree L, Oliver N, Lim JI. Accumulation of NH2-terminal fragment of connective tissue growth factor in the vitreous of patients with proliferative diabetic retinopathy. Diabetes Care 2004; 27: 758–64.10.2337/diacare.27.3.758Search in Google Scholar PubMed
143. Junglas B, Kuespert S, Seleem AA, Struller T, Ullmann S, Bösl M, Bosserhoff A, Köstler J, Wagner R, Tamm ER, Fuchshofer R. Connective tissue growth factor causes glaucoma by modifying the actin cytoskeleton of the trabecular meshwork. Am J Pathol 2012; 180: 2386–2403.10.1016/j.ajpath.2012.02.030Search in Google Scholar PubMed
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