Cyclic AMP stimulates renin gene transcription in juxtaglomerular cells
Cyclic AMP stimulates renin gene transcription in juxtaglomerular cells
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DOI：
10.1007/s00424-002-0818-9
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发表时间：
2002-06-01
影响因子：
4.5
通讯作者：
Kurtz, A
中科院分区：
文献类型：
--
作者：
Klar, J;Sandner, P;Kurtz, A
尽管环 AMP 信号级联被认为是肾近球 (JG) 细胞中肾素基因表达的主要激活剂，但 cAMP 发挥这种作用的分子途径仍然存在争议。在这项研究中，我们使用了小鼠 JG 细胞系 As4.1，它与天然 JG 细胞有许多功能相似之处。我们发现，IBMX 中的毛喉素（一种腺苷酸环化酶激活剂）随时间依赖性地增加肾素 mRNA 水平和肾素原分泌高达三倍。蛋白激酶 A 抑制剂（H-89，10 muM）显着减弱了毛喉素/IBMX 对肾素基因表达的刺激。 Forskolin/IBMX 对放线菌素 D (2 muM) 全面抑制转录后肾素 mRNA 的下降没有影响。相反，forskolin/IBMX 使肾素启动子 2.8 kb 片段的活性增加三倍。负责毛喉素/IBMX刺激作用的启动子区域被缩小到小鼠Renl(C)基因的三个4bp，这被称为推定的CRE位点。发现 CRE 结合蛋白在毛喉素/IBMX 刺激下发生磷酸化。因此，cAMP 很可能通过激活蛋白激酶来刺激 JG 细胞中的肾素基因表达。以及随后的 CRE 结合蛋白的磷酸化。
Although the cyclic AMP signalling cascade is considered to be the main activator of renin gene expression in renal juxtaglomerular (JG) cells, the molecular pathways along which cAMP exerts this effect remain a matter of controversy. Here in this study we used the mouse JG cell line As4.1, which shares a number of functional similarities with native JG cells. We found that forskolin, an activator of adenylate cyclase, in the presents of IBMX time-dependently increased renin mRNA levels and prorenin secretion up to threefold. The stimulation of renin gene expression by forskolin/IBMX was markedly attenuated by an inhibitor of protein kinase A (H-89, 10 muM). Forskolin/IBMX had no effect on the decline of renin mRNA after general inhibition of transcription by actinomycin D (2 muM). Conversely, forskolin/IBMX increased the activity of a 2.8-kb fragment of the renin promoter threefold. The promoter region responsible for the stimulatory effect of forskolin/IBMX was narrowed down to three 4 bp of the mouse Renl(C) gene, which are known as putative CRE-sites. The CRE-binding protein was found to be phosphorylated under forskolin/IBMX stimulation. It appears likely therefore that cAMP stimulates renin gene expression in JG cells by activating protein kinase; and subsequent phosphorylation of the CRE-binding protein.