Chen Yii-Shyuan, Wu Rui, Yang Xiaosong, Kou Shuping, MacDougald Ormond A, Yu Liqing, Shi Hang, Xue Bingzhong
Center for Obesity Reversal, Department of Biology, Georgia State University, Atlanta, GA, USA.
Department of Molecular &Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA.
Sci Rep. 2016 May 3;6:25283. doi: 10.1038/srep25283.
Both adipocytes and osteoblasts share the mesodermal lineage that derives from mesenchymal stem cells. Most studies investigating the mechanisms underlying the regulation of adipogenic or osteoblastogenic development focus on transcriptional pathways; little is known about the epigenetic mechanisms in this process. We thus determined the role of 5-aza-2'-deoxycytidine (5-Aza-dC), an inhibitor of DNA methylation, in the lineage determination between adipogenesis and osteoblastogenesis. Inhibiting DNA methylation in 3T3-L1 preadipocytes by 5-Aza-dC significantly inhibited adipogenesis whereas promoted osteoblastogenesis. This dual effect of 5-Aza-dC was associated with up-regulation of Wnt10a, a key factor determining the fate of the mesenchymal lineage towards osteoblasts. Consistently, IWP-2, an inhibitor of Wnt proteins, was found to prevent the anti-adipogenic effect of 5-Aza-dC in 3T3-L1 preadipocytes and block the osteoblastogenic effect of 5-Aza-dC in ST2 mesenchymal stem cell line. Finally, the Wnt10a 5'-region is enriched with CpG sites, whose methylation levels were markedly reduced by 5-Aza-dC. Thus we conclude that inhibiting DNA methylation by 5-Aza-dC mutual-exclusively regulates the lineage determination of adipogenesis and osteoblastogenesis by demethylating Wnt10a gene and upregulating its expression. Our study defines DNA methylation as a novel mechanism underlying adipocyte and bone cell development.
脂肪细胞和成骨细胞都源自间充质干细胞的中胚层谱系。大多数研究脂肪生成或成骨细胞发育调控机制的研究都集中在转录途径上；而对这一过程中的表观遗传机制却知之甚少。因此，我们确定了DNA甲基化抑制剂5-氮杂-2'-脱氧胞苷（5-Aza-dC）在脂肪生成和成骨细胞生成之间的谱系决定中的作用。用5-Aza-dC抑制3T3-L1前脂肪细胞中的DNA甲基化可显著抑制脂肪生成，而促进成骨细胞生成。5-Aza-dC的这种双重作用与Wnt10a的上调有关，Wnt10a是决定间充质谱系向成骨细胞命运的关键因子。同样，发现Wnt蛋白抑制剂IWP-2可阻止5-Aza-dC对3T3-L1前脂肪细胞的抗脂肪生成作用，并阻断5-Aza-dC对ST2间充质干细胞系的成骨细胞生成作用。最后，Wnt10a的5'-区域富含CpG位点，5-Aza-dC可使其甲基化水平显著降低。因此，我们得出结论，5-Aza-dC通过使Wnt10a基因去甲基化并上调其表达，相互排斥地调节脂肪生成和成骨细胞生成的谱系决定。我们的研究将DNA甲基化定义为脂肪细胞和骨细胞发育的一种新机制。
