High glucose levels upregulate upstream stimulatory factor 2 gene transcription in mesangial cells.
High glucose levels upregulate upstream stimulatory factor 2 gene transcription in mesangial cells.
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高葡萄糖水平上调系膜细胞中上游刺激因子 2 基因转录。
DOI：
10.1002/jcb.21585
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发表时间：
2008
影响因子：
4
通讯作者：
Wang,Shuxia
中科院分区：
文献类型：
--
作者：
Shi,Lihua;Liu,Shu;Nikolic,Dejan;Wang,Shuxia
之前，我们证明了上游刺激因子2（USF 2）介导肾小球系膜细胞中葡萄糖诱导的血小板反应蛋白1（TSP 1）基因表达和TGF-β活性升高，并在糖尿病肾脏并发症中发挥作用。在本研究中，我们进一步确定了高葡萄糖水平调节USF 2基因表达的分子机制。在原代大鼠系膜细胞中，我们发现葡萄糖处理时间和剂量依赖性上调USF 2表达（mRNA和蛋白质）。通过使用放线菌酮阻断从头蛋白质合成，发现在正常葡萄糖或高糖条件下USF 2降解的速率相似。高糖处理不改变USF 2 mRNA的稳定性。此外，高糖处理刺激USF 2基因启动子活性。通过使用荧光素酶启动子缺失试验、定点突变和反式激活试验，我们鉴定了USF 2基因启动子中的葡萄糖响应元件（相对于转录起始位点为-1，740至-1，620），并证明葡萄糖诱导的USF 2表达是通过USF 2启动子的cAMP响应元件结合蛋白（CREB）依赖性反式激活介导的。此外，siRNA介导的CREB敲低消除了葡萄糖诱导的USF 2表达。综上所述，这些数据表明，高葡萄糖水平通过CREB依赖性的USF 2启动子的反式激活上调系膜细胞中USF 2基因的转录。J.细胞。103：1952-1961，2007.© 2007 Wiley利斯公司
Previously, we demonstrated that upstream stimulatory factor 2 (USF2) mediates high glucose‐induced thrombospondin1 (TSP1) gene expression and TGF‐β activity in glomerular mesangial cells and plays a role in diabetic renal complications. In the present studies, we further determined the molecular mechanisms by which high glucose levels regulate USF2 gene expression. In primary rat mesangial cells, we found that glucose treatment time and dose‐dependently up‐regulated USF2 expression (mRNA and protein). By using cycloheximide to block the de novo protein synthesis, similar rate of USF2 degradation was found under either normal glucose or high glucose conditions. USF2 mRNA stability was not altered by high glucose treatment. Furthermore, high glucose treatment stimulated USF2 gene promoter activity. By using the luciferase‐promoter deletion assay, site‐directed mutagenesis, and transactivation assay, we identified a glucose‐responsive element in the USF2 gene promoter (−1,740 to −1,620, relative to the transcription start site) and demonstrated that glucose‐induced USF2 expression is mediated through a cAMP‐response element‐binding protein (CREB)‐dependent transactivation of the USF2 promoter. Furthermore, siRNA‐mediated CREB knock down abolished glucose‐induced USF2 expression. Taken together, these data indicate that high glucose levels up‐regulate USF2 gene transcription in mesangial cells through CREB‐dependent transactivation of the USF2 promoter. J. Cell. Biochem. 103: 1952–1961, 2007. © 2007 Wiley‐Liss, Inc.