Laboratory of Nutritional Physiology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan.
Division of Engineering, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan.
Sci Rep. 2017 Sep 20;7(1):11962. doi: 10.1038/s41598-017-12342-2.
We previously reported that induction of the adipocyte-specific gene adiponectin (Adipoq) during 3T3-L1 adipocyte differentiation is closely associated with epigenetic memory histone H3 acetylation on the transcribed region of the gene. We used 3T3-L1 adipocytes and Brd4 heterozygous mice to investigate whether the induction of Adipoq during adipocyte differentiation is regulated by histone acetylation and the binding protein bromodomain containing 4 (BRD4) on the transcribed region. Depletion of BRD4 by shRNA and inhibition by (+)-JQ1, an inhibitor of BET family proteins including BRD4, reduced Adipoq expression and lipid droplet accumulation in 3T3-L1 adipocytes. Additionally, the depletion and inhibition of BRD4 reduced the expression of many insulin sensitivity-related genes, including genes related to lipid droplet accumulation in adipocytes. BRD4 depletion reduced P-TEFb recruitment and histone acetylation on the transcribed region of the Adipoq gene. The expression levels of Adipoq and fatty acid synthesis-related genes and the circulating ADIPOQ protein level were lower in Brd4 heterozygous mice than in wild-type mice at 21 days after birth. These findings indicate that BRD4 regulates the Adipoq gene by recruiting P-TEFb onto acetylated histones in the transcribed region of the gene and regulates adipocyte differentiation by regulating the expression of genes related to insulin sensitivity.
我们之前报道过，在 3T3-L1 脂肪细胞分化过程中诱导脂肪细胞特异性基因脂联素（Adipoq）的表达与基因转录区域组蛋白 H3 乙酰化的表观遗传记忆密切相关。我们使用 3T3-L1 脂肪细胞和 Brd4 杂合子小鼠来研究在脂肪细胞分化过程中 Adipoq 的诱导是否受组蛋白乙酰化和转录区域上的含溴结构域蛋白 4（BRD4）结合蛋白的调节。shRNA 敲低 BRD4 和 BET 家族蛋白（包括 BRD4）抑制剂（+）-JQ1 的抑制作用降低了 3T3-L1 脂肪细胞中的 Adipoq 表达和脂滴积累。此外，BRD4 的耗尽和抑制降低了许多胰岛素敏感性相关基因的表达，包括与脂肪细胞中脂滴积累相关的基因。BRD4 耗竭降低了 P-TEFb 募集和 Adipoq 基因转录区域的组蛋白乙酰化。与野生型小鼠相比，出生后 21 天时，Brd4 杂合子小鼠的 Adipoq 基因和脂肪酸合成相关基因的表达水平以及循环 ADIPOQ 蛋白水平较低。这些发现表明，BRD4 通过将 P-TEFb 募集到基因转录区域的乙酰化组蛋白上来调节 Adipoq 基因，并通过调节与胰岛素敏感性相关的基因表达来调节脂肪细胞分化。
