Role of plasminogen activator inhibitor-2 (PAI-2) in keratinocyte differentiation
Introduction
The most important role of skin is regarded as a vital barrier against fluid loss, chemical and infectious agents, and UV light [1]. Much of this protective function is dependent on the epidermis, a multi-layered epithelium that is composed of various cell types, including keratinocytes and melanocytes [2]. Keratinocytes are the major cells in the epidermis that make the water-insoluble cornified cell envelope (CE), a key component of skin barrier, through highly sophisticated and tightly regulated process of differentiation [3], [4]. Keratinocyte progenitor cells in the basal layer proliferate and move upwardly, the differentiation process begins in the suprabasal layers and culminates in fully differentiated dead cells on the surface. Once basal cells become committed to the terminal differentiation program, the pattern of gene expression is drastically changed in a temporal manner. For example, the CE proteins such as involucrin, loricrin and filaggrin are highly increased, while the cytokeratin 5 and 14 are decreased [2]. Although a number of genes required for keratinocyte differentiation have been already discovered, it is likely that many of important molecules remain to be identified. In an attempt to identify the calcium-inducible genes in HaCaT keratinocytes, we previously found that plasminogen activator inhibitor type-2 (PAI-2) is related with the keratinocyte differentiation [5]. In this study, we investigated the putative role of PAI-2 in keratinocyte differentiation.
PAI-2 is an inhibitor of urokinase-type plasminogen activator (uPA), an extracellular serine proteinase that cleaves plasminogen to plasmin. PAI-2 was originally isolated from human placenta, however, it is now well established that PAI-2 is widely expressed in various cells and tissue fluids such as macrophages, fibroblasts, vascular cells, pregnancy plasma and gingival cervical fluid [6]. PAI-2 is also induced by the infection of a range of parasitic, viral and bacterial pathogens [7], [8], [9], [10]. Although PAI-2 is widely described as an inhibitor for uPA, the evidence indicates that PAI-2 is involved in many of physiological process including cell differentiation, tissue regrowth and regeneration. For instance, PAI-2 has recently been shown to have an intra-nuclear activity as a retinoblastoma protein (Rb)-binding protein. PAI-2 expression inhibits the Rb degradation, thereby playing a role for arresting cell growth and enhancing differentiation [11]. Furthermore, PAI-2 influences the transcription of viral genes through the regulation of Rb activity [12]. Interestingly, recent immunohistochemistry analysis indicates that most keratinocytes contain PAI-2 in a subpopulation of more differentiated cells, and PAI-2 becomes incorporated into the cornified envelope during terminal differentiation [13], [14]. Although its expression and putative role as a component of cornified envelope has been documented, the precise role of PAI-2 in keratinocyte differentiation remains to be elucidated. Here, we provide the evidence that PAI-2 affects the keratinocyte differentiation positively.
Section snippets
Immunohistochemistry
All skin samples were obtained under the informed consent of donors, in accordance with the ethical committee approval process of the Chungnam National University Hospital. Skin specimens were fixed in 5% paraformaldehyde, then paraffin embedded. Sections of skin specimens were dewaxed, rehydrated, and washed three times with phosphate-buffered saline (PBS). After treatment with proteinase K (1 mg/ml) for 5 min at 37 °C, sections were treated with H2O2 for 10 min at room temperature, blocked in
Expression of PAI-2 in epidermis and cultured keratinocytes
To examine the expression of PAI-2, we performed immunohistochemical staining against normal skin tissue. The expression of PAI-2 was observed in epidermis, particularly with intense staining in upper granular layer (Fig. 1A). In reconstituted epidermis, the expression of PAI-2 was also increased in upper granular layer (Fig. 1B). This result is consistent with previous report, in which PAI-2 expression is increased in upper granular layer and coincides with transglutaminase 1 expression [19].
Discussion
In this study, we investigated the putative role of PAI-2 in keratinocyte differentiation, using adenoviral gene delivery system. We found that PAI-2 was expressed at comparatively high levels in differentiated epidermal keratinocytes in vivo and in vitro. When PAI-2 was overexpressed, keratinocyte differentiation was enhanced in terms of increasing differentiation markers such as involucrin, keratin 10 and filaggrin. Furthermore, forced PAI-2 expression decreased keratinocyte proliferation and
Acknowledgements
This study was supported by a grant of the Korea Health 21 R&D Project from the Korea Ministry of Health, Welfare and Family Affairs (01-PJ3-PG6-01GN12-0001) and by a grant of the National Research Foundation of Korea (KRF-2008-314-E00152). Jang S and Sohn KC were supported by Brain Korea 21 Research Fellowship from the Korea Ministry of Education, Science and Technology.
References (24)
- et al.
The cornified envelope of terminally differentiated human epidermal keratinocytes consists of cross-linked protein
Cell
(1977) - et al.
Biological and clinical aspects of plasminogen activator inhibitor type 2
Blood
(1995) - et al.
Unique gene expression profiles of human macrophages and dendritic cells to phylogenetically distinct parasites
Blood
(2003) - et al.
Plasminogen activator inhibitor type 2: an intracellular keratinocyte differentiation product that is incorporated into the cornified envelope
Exp Cell Res
(1995) - et al.
S100A11, S100A10, annexin I, desmosomal proteins, small proline-rich proteins, plasminogen activator inhibitor-2, and involucrin are components of the cornified envelope of cultured human epidermal keratinocytes
J Biol Chem
(1997) - et al.
Prediction and evaluation of protein–protein interaction in keratinocyte differentiation
Biochem Biophys Res Commun
(2008) - et al.
Novel synthetic ceramide derivatives increase intracellular calcium levels and promote epidermal keratinocyte differentiation
J Lipid Res
(2007) - et al.
Pitx2, a beta-catenin-regulated transcription factor, regulates the differentiation of outer root sheath cells cultured in vitro
J Dermatol Sci
(2009) - et al.
Keratinocyte survival, differentiation, and death: many roads lead to mitogen-activated protein kinase
J Investig Dermatol Symp Proc
(2002) - et al.
Plasminogen activator inhibitor type 2 inhibits tumor necrosis factor alpha-induced apoptosis. Evidence for an alternate biological function
J Biol Chem
(1995)
Signaling pathways and genes that inhibit pathogen-induced macrophage apoptosis-CREB and NF-κB as key regulators
Immunity
Identification of calcium-inducible genes in primary keratinocytes using suppression-subtractive hybridization
Exp Dermatol
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These authors contributed equally to this study.