TET1 promotes adipogenesis through DNA demethylation [RNA-seq]

Adipose tissue is important for systemic metabolic homeostasis in response to environmental changes, and adipogenesis involves dynamic transcriptional regulation. DNA methylation on cytosine (C) of CpG (5mC) is an abundant epigenetic modification that mediates genomic imprinting and regulates gene expression. TET family enzymes (TET1, TET2 and TET3) oxidize the 5mC in DNA to 5-hydroxylmethylcytosine (5hmC), which associates with transcriptional activation. Through a phenotypic screen, we found TET inhibition decreased adipocyte differentiation from mesenchymal stem cells (MSCs). Comparing with the undifferentiated MSCs, the differentiated adipocytes exhibited much higher levels of 5hmC and slightly increased 5fC and 5caC. Higher 5hmC associated with better differentiation at single cell level. TET1 is upregulated in differentiation and depletion of it significantly impaired the gain of 5hmC. Furthermore, Tet1 depletion significantly hampered the adipocyte differentiation in vitro and adipose tissue maintenance in vivo. Using RNA-seq, 5mC and 5hmC-DNA immunoprecipitation, we found that Tet1 knockout led to decreased expression of genes associated with lipid metabolism and fat cell differentiation. Genes with loss of 5mC or gain of 5hmC in adipocytes include Lipe, Bmp4 and Rxra etc. Rxra is one of the critical TET1 modulated genes for adipose development, as RXRα agonist partially rescued the inhibitory effect of Tet1 knockout. Together, TET1-mediated active DNA demethylation plays an important role in adipose tissue. Examination of polyA RNA in C3H10T1/2 cells after different time points of differentiation