TG-interacting factor is required for the differentiation of preadipocytes
TG-interacting factor is required for the differentiation of preadipocytes
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DOI：
10.1194/jlr.m700578-jlr200
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发表时间：
2008-06-01
影响因子：
6.5
通讯作者：
Hasegawa, Koji
中科院分区：
文献类型：
--
作者：
Horie, Takahiro;Ono, Koh;Hasegawa, Koji
内脏脂肪组织的堆积与胰岛素抵抗和代谢综合征密切相关。因此，鉴定脂肪细胞分化所需的基因非常重要。为了鉴定 3T3-L1 前脂肪细胞分化为成熟脂肪细胞所需的基因，我们使用逆转录病毒插入介导的随机诱变来产生失去分化为成熟脂肪细胞能力的 3T3-L1 细胞系。其中一个被鉴定的基因是 TG 相互作用因子 (TGIF)，这是一种 DNA 结合同源域蛋白，已被证明可以抑制 Smad 介导的转化生长因子 β (TGF-β) 调节转录的激活。在TGIF破坏的3T3-L1前脂肪细胞克隆中，与野生型克隆相比，分化为成熟脂肪细胞的速率明显降低。慢病毒介导的RNAi抑制TGIF也抑制3T3-L1细胞的分化。胰岛素特别增加了 TGIF 蛋白的丰度，主要是通过增强其稳定性。此外，胰岛素导致TGIF在细胞核中快速积累。外源 TGIF 的强制表达抑制了 3T3-L1 中内源和过表达的 Smad2/3 介导的启动子活性。这些发现表明，胰岛素通过稳定假定的 Smad 转录辅阻遏物 TGIF 来特异性拮抗前脂肪细胞中的 TGF-β 信号传导，并调节脂肪细胞分化。
The accumulation of visceral adipose tissue is closely associated with insulin resistance and metabolic syndrome. Therefore, it is important to identify genes that are required for adipocyte differentiation. To identify genes that are required for the differentiation of 3T3-L1 preadipocytes into mature adipocytes, we used retrovirus insertion-mediated random mutagenesis to generate 3T3-L1 cell lines that lose their ability to differentiate into mature adipocytes. One of the genes identified was TG-interacting factor (TGIF), a DNA binding homeodomain protein that has been demonstrated to suppress Smad-mediated activation of transforming growth factor beta (TGF-beta)-regulated transcription. In the TGIF-disrupted clone of 3T3-L1 preadipocytes, the rate of differentiation into mature adipocytes was clearly reduced compared with that in the wild-type clone. Suppression of TGIF by lentivirus-mediated RNAi also inhibited the differentiation of 3T3-L1 cells. Insulin specifically increased the abundance of TGIF protein, primarily by enhancing its stability. In addition, insulin caused the rapid accumulation of TGIF in the nuclei. Forced expression of exogenous TGIF repressed both endogenous and overexpressed Smad2/3mediated promoter activity in 3T3-L1. These findings suggest that insulin specifically antagonizes TGF-beta signaling in preadipocytes by stabilizing the putative Smad transcriptional corepressor TGIF and regulates adipocyte differentiation.