Set7/9, a methyltransferase, regulates the thermogenic program during brown adipocyte differentiation through the modulation of p53 acetylation
Graphical abstract
Introduction
Adipocytes play important roles in energy homeostasis in human and other mammals, and are thus closely associated with metabolic disorders such as obesity and type 2 diabetes. There are two distinct types of adipocytes, white and brown adipocytes, which have opposite functions with regard to the energy balance (Bae et al., 2012, Kim et al., 2015a). White adipocytes store excess energy as triglycerides in lipid droplets, whereas brown adipocytes release energy in the form of heat through thermogenesis. Unlike white adipocytes, the thermogenic capacity of brown adipocytes results from the expression of the brown fat-defining marker, uncoupling protein-1 (UCP-1), located in the mitochondrial inner membrane. UCP-1 causes a proton leak across the inner membrane of mitochondria, thereby converting chemical energy into heat. Therefore, brown adipocytes have been considered as the potential target for creating strategies to treat obesity and its related diseases (Park et al., 2014).
Both brown and white adipocytes are derived from mesenchymal stem cells (MSCs) (Park et al., 2014). White adipocyte differentiation is regulated by positive and negative stimuli, including a variety of hormones, growth factors and transcription factors (Kim et al., 2013a, Kim et al., 2013b, Lee et al., 2016; Rosen and Spiegelman, 2000). Although the molecular mechanism underlying brown adipocyte differentiation has not been as extensively studied as that of white adipocyte differentiation (Choi et al., 2013a, Hilton et al., 2015, Rosen and Spiegelman, 2000), the differentiation process of brown and white adipocytes has a similar transcriptional pattern. Peroxisome proliferator-activated receptor-γ (PPAR-γ) and C/EBP-α, master transcriptional regulators in white adipocyte differentiation, are also essential factors in brown adipocyte differentiation, and their expression level has been shown to increase during differentiation of brown adipocytes. Nevertheless, other transcriptional regulators, such as PPAR-γ coactivator-1α (PGC-1α) and PR domain containing 16 (PRDM16), play important roles in brown adipocyte-specific expression of UCP-1 (Seale et al., 2007). These transcription factors and any other factors that regulate thermogenesis are key regulators of the differentiation and functions of brown adipocytes.
Post-translational modifications (PTMs) refer to the covalent and generally enzymatic modifications of protein, and comprise one of the most important approaches for regulation of biological processes via alteration of the physiological behavior of that protein, such as regulation of protein-protein interactions, stability, localization, and/or enzymatic activities (Kim et al., 2012). A number of PTMs occur on non-histone proteins as well as histones (Biggar and Li, 2015, Zhou et al., 2014). The attachment and removal of most PTMs are catalyzed by enzymes. Recently, PTM-regulatory enzymes have emerged as major drug targets. Although phosphorylation, acetylation, and ubiquitination have been extensively investigated, methylation of non-histone proteins has also been known as an important PTM for influencing protein behaviors (Biggar and Li, 2015, Zhang et al., 2012).
We extensively assessed the changes in the expression levels of methyltransferases and demethylases during brown adipocyte differentiation. Several enzymes displaying differential expression patterns were identified. Among these, we focused on methyltransferase Set7/9. Set7/9 catalyzes the methylation at histone H3K4, resulting in gene activation (Nishioka et al., 2002a, Nishioka et al., 2002b). Set7/9 also induces non-histone protein lysine methylation, such as that for p53, TAF10, and DNA methyltransferase 1 (DNMT1) (Couture et al., 2006, Pradhan et al., 2009). In particular, Set7/9 modulates p53 activity via direct interaction (Chuikov et al., 2004) or interaction with Sirt1 (Liu et al., 2011). p53 is known to be required for differentiation into mature brown adipocytes (Molchadsky et al., 2013). Here, we investigated the functional roles of Set7/9 during brown adipocyte differentiation, mainly focusing on the modulation of p53 activity.
Section snippets
Cell culture and brown adipocyte differentiation
Primary brown progenitor cells were obtained from the interscapular brown adipose tissue of 1-to-3-day-old mice and isolated cells were cultured as previously described (Kim et al., 2015b). The immortalized brown preadipocyte cell line was kindly provided by Dr. Shingo Kajimura (UCSF). Cells were grown in Dulbecco's modified Eagle's medium (DMEM) containing 1% antibiotic/antimycotic solution and 10% fetal bovine serum (FBS) at 37 °C in a humidified atmosphere with 5% CO2. For brown adipogenic
The expression level of Set7/9 decreased during brown adipocyte differentiation
Brown preadipocytes were cultured, and differentiation into mature brown adipocytes was induced by culture in differentiation cocktail media (Choi et al., 2013a, Kim et al., 2015b, Son et al., 2015). To identify the methyltransferases and demethylases involved in brown adipocyte differentiation, we used a qPCR array for samples derived from both preadipocytes and mature brown adipocytes. From a total of 31 methyltransferases and 18 demethylases, several enzymes showed differential expression
Discussion
A number of PTMs occur on non-histone proteins as well as histones and control protein-protein interactions, stability, intracellular localization, and enzymatic activities of proteins involved in various cellular processes. Relatively few non-histone proteins have been reported that can be modified by lysine methylation. The enzymes involved in lysine methylation were first found to target histone and thus were initially termed as histone methyltransferases and histone demethylases. According
Conflict of interest
The authors have no conflicts of interest and declare no competing financial interests.
Acknowledgments
We would like to thank Professors Sayeon Cho, Seung Jun Kim, and Sang J. Chung for the continuous encouragement and helpful advice. This work was supported by grants from the KRIBB and from the Research Program (grants 2006-2004112, 2012M3A9C7050101, 2015M3A9B5030308, and 2015M3A9D7029882) through the National Research Foundation of Korea.
References (33)
- et al.
Emerging technologies to map the protein methylome
J. Mol. Biol.
(2014) - et al.
Role of developmental transcription factors in white, brown and beige adipose tissues
Biochim. Biophys. Acta
(2015) - et al.
Acceleration of adipogenic differentiation via acetylation of malate dehydrogenase 2
Biochem. Biophys. Res. Comm.
(2013) - et al.
Retinoic acid inhibits adipogenesis via activation of Wnt signaling pathway in 3T3-L1 preadipocytes
Biochem. Biophys. Res. Commun.
(2013) - et al.
Acetylation of malate dehydrogenase 1 promotes adipogenic differentiation via activating its enzymatic activity
J. Lipid Res.
(2012) - et al.
MAP kinase phosphatase3 inhibits brown adipocyte differentiation via regulation of Erk phosphorylation
Mol. Cell. Endocrinol.
(2015) - et al.
Methylation of p53 by Set7/9 mediates p53 acetylation and activity in vivo
Mol. Cell
(2008) - et al.
p53-dependent transcription and tumor suppression are not affected in Set7/9-deficient mice
Mol. Cell
(2011) - et al.
PR-Set7 is a nucleosome-specific methyltransferase that modifies lysine 20 of histone H4 and is associated with silent chromatin
Mol. Cell
(2002) - et al.
Transcriptional control of brown fat determination by PRDM16
Cell Metab.
(2007)
Proteomic analysis of protein methylation on the yeast Saccharomyces cerevisiae
J. Proteomics
Role of histone acetyltransferases and histone deacetylases in adipocyte differentiation and adipogenesis
Eur. J. Cell Biol.
Involvement of protein tyrosine phosphatases in adipogenesis: new anti-obesity targets?
BMB Rep.
Non-histone protein methylation as a regulator of cellular signaling and function
Nat. Rev. Mol. Cell Biol.
A mass-tolerant database search a large proportion of unassigned spectra in shortgun proteomics as modified peptides
Nat. Biotechnol.
Protein tyrosine phosphatase profiling studies during brown adipogenic differentiation of mouse primary brown preadipocytes
BMB Rep.
Cited by (15)
Regulation of adipogenesis by histone methyltransferases
2024, DifferentiationGATA3 induces the upregulation of UCP-1 by directly binding to PGC-1α during adipose tissue browning
2020, Metabolism: Clinical and ExperimentalCitation Excerpt :For analysis of mitochondrial DNA (mtDNA), total genomic DNA was isolated using the Exgene™ tissue SV DNA mini Kit (Geneall, Korea) from inguinal adipocytes. Then, mtDNA was amplified using mtDNA-specific primers and was normalized to genomic DNA by primers amplifying TATA box binding protein (TBP) from genomic DNA as previously described [29]. All experiments were independently analyzed at least 3 times.
Computational discovery and biological evaluation of novel inhibitors targeting histone-lysine N-methyltransferase SET7
2020, Bioorganic and Medicinal ChemistryCitation Excerpt :Because SET7 interacts with diverse substrates, it plays critical roles in the regulation of the cell cycle,29 RNA polymerase II-dependent gene transcription,30 cell differentiation and DNA double-strand break repair9. Especially, SET7 involved in the process of many diseases, including breast cancer,10 prostate cancer,31 ovarian cancer,32 hepatocellular carcinoma,33 diabetes,34 peritoneal fibrosis,35 pulmonary fibrosis,36 and obesity.1 Therefore, SET7 is becoming a potential target to develop new drugs for different diseases.
IDH1-dependent α-KG regulates brown fat differentiation and function by modulating histone methylation
2020, Metabolism: Clinical and ExperimentalCitation Excerpt :The conditions used for adipogenic differentiation of C3H10T1/2 cells were previously described [32]. Lipid droplets of differentiated brown adipocytes were subjected to Oil-Red-O staining, as described in our previous study [33]. Briefly, cultured cells were washed twice with phosphate-buffered saline (PBS) and fixed for 30 min with 10% formaldehyde at room temperature.
p53 as a double-edged sword in the progression of non-alcoholic fatty liver disease
2018, Life SciencesCitation Excerpt :Moreover, p53 inhibits the expression of SREBP1c in adipose tissue of mice and thereby affects its target genes: fatty acid synthase (FAS), acetyl coenzyme A carboxylase (ACC) and adenosine triphosphate citrate lyase (ACLY), all of which participate in fatty acid synthesis [57,58]. As an upstream nuclear receptor of SREBP1c, PPARγ is an essential factor in adipocyte differentiation, and it has been shown that the p53 expression level is increased during the differentiation process [59]. Accordingly, the aberrant upregulation of the expression of PPARγ by p53 may be responsible for enhanced lipid accumulation [60].
Nutraceutical Food: Composition, Biosynthesis, Therapeutic Properties, and Applications
2018, Alternative and Replacement Foods
- 1
These authors contributed equally to this work.