Insulin and sterol-regulatory element-binding protein-1c (SREBP-1C) regulation of gene expression in 3T3-L1 adipocytes -: Identification of CCAAT/enhancer-binding protein β as an SREBP-1c target
Insulin and sterol-regulatory element-binding protein-1c (SREBP-1C) regulation of gene expression in 3T3-L1 adipocytes -: Identification of CCAAT/enhancer-binding protein β as an SREBP-1c target
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DOI：
10.1074/jbc.m203913200
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发表时间：
2002-09-20
影响因子：
4.8
通讯作者：
Krief, S
中科院分区：
文献类型：
--
作者：
Le Lay, S;Lefrère, I;Krief, S
我们评估了固醇调节元件结合蛋白（SREBP）-1c作为胰岛素转录效应的一般介体的假设，重点是脂肪细胞，其中胰岛素深刻地影响特定的基因表达。我们使用真实的时间定量逆转录酶-PCR来监测涵盖广泛脂肪细胞功能的约50个基因表达的变化，比较了胰岛素治疗与腺病毒过表达显性阳性或显性阴性SREBP-1c突变体在3 T3-L1脂肪细胞中的影响。正如预期的那样，胰岛素上调、显性阳性刺激和显性阴性降低了先前表征的直接SREBP靶点（FAS、SCD-1和低密度脂蛋白受体）。我们还在脂肪细胞中鉴定了三种新的SREBP-1c转录靶点，并通过连续试验证实：纤溶酶原激活物抑制剂1、CCAAT/增强子结合蛋白δ（C/EBP δ）和C/EBP β。由于大多数胰岛素调节基因也受到SREBP-1c突变体的调节，我们的数据证实：1）SREBP-1c是脂肪细胞中胰岛素转录效应的重要介导因子，2）C/EBP β受SREBP-1c的直接控制，如SREBP-1c通过典型SREBP结合位点激活C/EBP β启动子转录的能力所证明的。因此，胰岛素和/或SREBP-1c在成熟脂肪细胞中的某些作用可能需要C/EBP β或C/EBP δ作为转录中继。
We evaluated the hypothesis of sterol-regulatory element-binding protein (SREBP)-1c being a general mediator of the transcriptional effects of insulin, with a focus on adipocytes, in which insulin profoundly influences specific gene expression. Using real time quantitative reverse transcriptase-PCR to monitor changes in the expression of about 50 genes that cover a wide range of adipocyte functions, we have compared the impact of insulin treatment with that of adenoviral overexpression of either dominant positive or dominant negative SREBP-1c mutants in 3T3-L1 adipocytes. As expected, insulin up-regulated, dominant positive stimulated, and dominant negative decreased previously characterized direct SREBP targets (FAS, SCD-1, and low density lipoprotein receptor). We also identified three novel SREBP-1c transcriptional targets in adipocytes, which were confirmed by run-on assays: plasminogen activator inhibitor 1, CCAAT/enhancer-binding protein delta (C/EBPdelta), and C/EBPbeta. Because most insulin-regulated genes were also modulated by SREBP-1c mutants, our data establish that 1) SREBP-1c is an important mediator of insulin transcriptional effects in adipocytes, and 2) C/EBPbeta is under the direct control of SREBP-1c, as demonstrated by the ability of SREBP-1c to activate the transcription from C/EBPbeta promoter through canonical SREBP binding sites. Thus, some of the effects of insulin and/or SREBP-1c in mature fat cells might require C/EBPbeta or C/EBPdelta as transcriptional relays.