Epigenetic programming of Dnmt3a mediated by AP2α is required for granting preadipocyte the ability to differentiate

Abstract

Adipogenesis has an important role in regulating energy homeostasis in mammals. 3T3-L1 preadipocytes have been widely used as an in vitro model for analyzing the molecular mechanism of adipogenesis. Previous reports indicated that the stage of contact inhibition (CI), through which the proliferating cells exit from the cell cycle, was required for granting preadipocyte the ability to differentiate. While this kind of the granting mechanism remains elusive. In the present study, we showed that DNA (cytosine-5) methyltransferase 3a (Dnmt3a) was upregulated at both the mRNA and protein level during the CI stage, and resulted in increasing promoter methylation of adipogenic genes. We further identified that the expression of Activator protein 2α (AP2α), a member of the transcription factor activator protein 2 (AP2) family, was highly correlated with the expression of Dnmt3a during the CI stage. In addition, we showed that AP2α transcriptionally upregulated Dnmt3a by directly binding to its proximal promoter region. Importantly, treatment of 3T3-L1 preadipocytes with AP2α-specific siRNAs inhibited the preadipocyte differentiation in a stage-dependent manner, supporting the conclusion that AP2α has an important role during the CI stage. Furthermore, overexpression of Dnmt3a partially rescued the impairment of adipogenesis induced by AP2α knockdown. Collectively, our findings reveal that AP2α is an essential regulator for granting preadipocyte the ability to differentiate through the upregulation of Dnmt3a expression during the CI stage.

Altered PTPRD DNA Methylation Associates with Restricted Adipogenesis in Healthy First-Degree Relatives of Type 2 Diabetes Subjects

“…Indeed, previous studies document that DNMT3A inactivation decreases methylation at the genome-wide level in both human and mouse embryonic stem cells [38,39]. Evidence has also been reported that DNMT3A deficiency restricts adipogenesis [40,41]. We now find that the reduced expression of DNMT3A negatively correlates with SAT adipose cell hypertrophy in FDR, where the increased adipose cell size is a marker of impaired adipogenesis [2].…”

The role of DNA methylation in thermogenic adipose biology

“…However, the opposite effect is observed when the inhibitor is added at a later stage of differentiation [39]. Knockdown of Dnmt1 and Dnmt3a during clonal expansion or early adipogenesis (day 0-2) impairs 3T3-L1 adipogenesis [39][40][41] but promotes lipid accumulation when knocked down on day 5 [39].…”

Thy1 (CD90) expression is regulated by DNA methylation during adipogenesis

“…Although changes in DNA methylation patterns at the Thy1 locus have not been characterized in the context of adipogenesis, recent reports have shown that DNA methylation changes are an integral part of adipocyte formation (24,25). In the most widely used and wellaccepted model of in vitro adipogenesis, the murine 3T3-L1 preadipocyte line, global DNA methylation has been shown to increase during adipogenesis (26,27). Interestingly, addition of the DNA methylation inhibitor 5aza-29-deoxycytidine (5-aza-dC) at the onset of adipogenic differentiation can completely block adipocyte formation, suggesting that DNA methylation changes are essential for adipogenesis (27,28).…”