Lee Yun Sok, Sohn Dong Hyun, Han Daehee, Lee Han-Woong, Seong Rho Hyun, Kim Jae Bum
Department of Biological Sciences, Seoul National University, San 56-1, Sillim-Dong, Kwanak-Gu, Seoul 151-742, South Korea.
Mol Cell Biol. 2007 Jan;27(2):438-52. doi: 10.1128/MCB.00490-06. Epub 2006 Oct 30.
Insulin plays a critical role in whole-body energy homeostasis by regulating lipid and glucose metabolism. In fat and liver tissues, ADD1/SREBP1c is a key transcription factor to mediate insulin-dependent regulation of gene expression. Although transcriptional and proteolytic activation of ADD1/SREBP1c has been studied intensively, the mechanism by which insulin regulates expression of its target genes with ADD1/SREBP1c at the chromatin level is unclear. Here, we reveal that SWI/SNF chromatin remodeling factors interact with the ADD1/SREBP1c and actively regulate insulin-dependent gene expression. Insulin enhanced recruitment of SWI/SNF chromatin remodeling factors to its target gene promoters with concomitant changes in the chromatin structures as well as gene expression. Furthermore, in vivo overexpression of BAF155/SRG3, a component of the SWI/SNF complex, substantially promoted insulin target gene expression and insulin sensitivity. Taken together, our results suggest that the SWI/SNF chromatin remodeling complexes confer not only insulin-dependent gene expression but also insulin sensitivity in vivo via interaction with ADD1/SREBP1c.
胰岛素通过调节脂质和葡萄糖代谢,在全身能量稳态中发挥关键作用。在脂肪和肝脏组织中,ADD1/SREBP1c是介导胰岛素依赖性基因表达调控的关键转录因子。尽管对ADD1/SREBP1c的转录和蛋白水解激活已进行了深入研究,但胰岛素在染色质水平上通过ADD1/SREBP1c调节其靶基因表达的机制尚不清楚。在此,我们揭示SWI/SNF染色质重塑因子与ADD1/SREBP1c相互作用,并积极调节胰岛素依赖性基因表达。胰岛素增强了SWI/SNF染色质重塑因子向其靶基因启动子的募集,同时伴随着染色质结构以及基因表达的变化。此外,在体内过表达SWI/SNF复合物的一个组分BAF155/SRG3,可显著促进胰岛素靶基因表达和胰岛素敏感性。综上所述,我们的结果表明,SWI/SNF染色质重塑复合物通过与ADD1/SREBP1c相互作用,不仅赋予体内胰岛素依赖性基因表达,还赋予胰岛素敏感性。