The Peroxisome Proliferator-Activated Receptor γ/Retinoid X Receptor α Heterodimer Targets the Histone Modification Enzyme PR-Set7/Setd8 Gene and Regulates Adipogenesis through a Positive Feedback Loop

Abstract

Control of cell differentiation occurs through transcriptional mechanisms and through epigenetic modification. Using a chromatin immunoprecipitation-on-chip approach, we performed a genome-wide search for target genes of peroxisome proliferator-activated receptor ␥ (PPAR␥) and its partner protein retinoid X receptor ␣ during adipogenesis. We show that these two receptors target several genes that encode histone lysine methyltransferase SET domain proteins. The histone H4 Lys 20 (H4K20) monomethyltransferase PR-Set7/Setd8 gene is upregulated by PPAR␥ during adipogenesis, and the knockdown of PR-Set7/Setd8 suppressed adipogenesis. Intriguingly, monomethylated H4K20 (H4K20me1) levels are robustly increased toward the end of differentiation. PR-Set7/Setd8 positively regulates the expression of PPAR␥ and its targets through H4K20 monomethylation. Furthermore, the activation of PPAR␥ transcriptional activity leads to the induction of H4K20me1 modification of PPAR␥ and its targets and thereby promotes adipogenesis. We also show that PPAR␥ targets PPAR␥2 and promotes its gene expression through H4K20 monomethylation. Our results connect transcriptional regulation and epigenetic chromatin modulation through H4K20 monomethylation during adipogenesis through a feedback loop.Adipocytes play a central role in energy balance, both as reservoirs of fuel and as endocrine cells, secreting factors that regulate whole-body energy metabolism. Because of the rising incidence of obesity, understanding the adipocyte is increasingly important. The process of adipocyte differentiation represents the extraordinarily coordinated regulation of multiple transcriptional systems that direct multipotent stem-cell precursors to differentiate into fully mature, functionally distinct cell types.The 3T3-L1 preadipocyte cell line has been one of the most well-characterized and widely used models for studying adipocyte differentiation (7). C/EBP␤ and C/EBP␦ are induced very early during differentiation, and these in turn activate two critical proadipogenic transcription factors, peroxisome proliferator-activated receptor ␥ (PPAR␥) and C/EBP␣. PPAR␥ and C/EBP␣ mutually stimulate each other and mediate the transition to the adipocyte phenotype (6,15,32). Recently, a number of transcription factors have been identified as regulators of adipogenesis, including GATA2 (30, 31), the Krüp-pel-like factor (KLF) family (2, 20, 24), and Nr2f2 (35).PPAR␥, a prototypical member of the nuclear receptor superfamily, is activated by natural ligands, such as arachidonic acid metabolites and fatty acid-derived components, and by the insulin-sensitizing thiazolidinedione drugs. In white and brown preadipocyte cell lines, the activation of PPAR␥ by thiazolidinediones results in robust differentiation into adipocytes. The action of PPAR␥ is mediated by two protein isoforms: the widely expressed PPAR␥1 and PPAR␥2, which is restricted to adipose tissue. The expression of each isoform is driven by a specific promoter that confers the distinct tissue-specific expression and...

Sox21 Promotes Hippocampal Adult Neurogenesis via the Transcriptional Repression of theHes5Gene

“…ChIP was performed as described previously (Kaneshiro et al, 2007;Wakabayashi et al, 2009) with some modifications. Briefly, for ChIP-quantitative PCR (qPCR), AHP cells were harvested, and genomic DNA was cross-linked using 1% formaldehyde overnight at 4°C.…”

A chromatin perspective of adipogenesis

“…108 In a feedback loop, the H4K20 HMT Set7/Setd8 is upregulated by PPARg during adipogenesis, at the time that this enzyme positively regulates the expression of PPARg and its target genes trough H4K20 monomethylation.…”

“…75,76 Decrease of H3K27/H3K9 methylation is observed in adipogenic promoters, accompanied by increased histone acetylation and H3K4/ H3K20 methylation. 38,50,108 Another characteristic feature during terminal differentiation of adipocytes is the spread of di and tri-methylation of H3K4, acetylation of H3 and the Pol II to the coding region of the adipogenic genes, coinciding with high levels of transcription of those genes. 38,50 in cell differentiation, including adipogenesis.…”

Histone H4 Lys 20 monomethylation by histone methylase SET8 mediates Wnt target gene activation

“…A genomic screen found that H4K20me-1 was enriched in the coding regions of active genes, hinting at a positive role of H4K20me-1 in gene transcription (12). More recent evidence has shown that SET8 and H4K20me-1 play a positive role in peroxisome proliferator-activated receptor (PPAR)γ expression and adipogenesis (13).…”