TRANSCRIPTIONAL DOWN-REGULATION BY INSULIN OF THE BETA(3)-ADRENERGIC RECEPTOR EXPRESSION IN 3T3-F442A ADIPOCYTES - A MECHANISM FOR REPRESSING THE CAMP SIGNALING PATHWAY
TRANSCRIPTIONAL DOWN-REGULATION BY INSULIN OF THE BETA(3)-ADRENERGIC RECEPTOR EXPRESSION IN 3T3-F442A ADIPOCYTES - A MECHANISM FOR REPRESSING THE CAMP SIGNALING PATHWAY
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DOI：
10.1073/pnas.91.12.5677
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发表时间：
1994-06-07
影响因子：
11.1
通讯作者：
PAIRAULT, J
中科院分区：
文献类型：
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作者：
FEVE, B;ELHADRI, K;PAIRAULT, J
在小鼠3 T3-F442 A脂肪细胞中研究了胰岛素对三种β-肾上腺素能受体亚型（β-AR）的调节。测量I-125标记的（-）-氰基吲哚酚与脂肪细胞膜结合的饱和和竞争实验表明，细胞暴露于胰岛素4天导致脂肪细胞的主要β-AR组分β（3）-AR的密度降低3.5倍，而β（1）-AR位点保持不变，β（2）-AR检测不到。这与β（3）-AR选择性激动剂CGP 12177、ICI 201651和BRL 37344在刺激腺苷酸环化酶中的较低效力相关。北方印迹分析表明，胰岛素诱导β（3）-AR mRNA水平迅速和急剧下降。这种效应在低胰岛素浓度（EC（50）= 3 nM）下可检测到，在胰岛素样生长因子I存在下未观察到，表明胰岛素受体介导的现象。逆转录酶-PCR分析显示，与胰岛素对β（3）-AR mRNA的显著下调作用相反，胰岛素并没有改变β（1）-和β（2）-AR转录物的水平。通过核连续试验评估，胰岛素在30分钟内抑制β（3）-AR基因转录率90%。mRNA周转实验表明，β（3）-AR mRNA的半衰期较短（90分钟），不受胰岛素影响。这些发现证明了胰岛素对β-AR亚型表达的遗传控制，并揭示了这种激素对脂肪细胞中cAMP依赖性生物过程的调节机制。
Modulation of the three beta-adrenergic receptor subtypes (beta-ARs) by insulin was investigated in mouse 3T3-F442A adipocytes. Saturation and competition experiments measuring binding of I-125-labeled (-)-cyanopindolol to adipocyte membranes demonstrated that cell exposure to insulin for 4 days caused a 3.5-fold decrease in the density of the major beta-AR component of the adipocyte, the beta(3)-AR, while beta(1)-AR sites remained unchanged and beta(2)-ARs were undetectable. This correlated with a lower potency of the beta(3)-AR-selective agonists CGP12177, ICI201651, and BRL37344 in stimulating adenylate cyclase. Northern blotting analysis indicated that insulin induced a rapid and sharp decrease in beta(3)-AR mRNA levels. This effect was detectable at low insulin concentrations (EC(50) = 3 nM) and was not observed in the presence of insulin-like growth factor I, suggesting an insulin receptor-mediated phenomenon. Reverse transcriptase-PCR analysis showed that, in contrast to its dramatic down-regulatory effect on beta(3)-AR mRNA, insulin did not modify the levels of beta(1)- and beta(2)-AR transcripts. As assessed by nuclear run-on assays, insulin inhibited the beta(3)-AR gene transcription rate by 90% within 30 min. mRNA turnover experiments showed that the half-life of beta(3)-AR mRNA was short (90 min) and remained unaffected by insulin. These findings demonstrate the genetic control of a beta-AR subtype expression by insulin and reveal a mechanism for the regulation by this hormone of cAMP-dependent biological processes in adipocytes.