Molecular mechanisms of glucose action on angiotensinogen gene expression in rat proximal tubular cells.
Molecular mechanisms of glucose action on angiotensinogen gene expression in rat proximal tubular cells.
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DOI：
10.1046/j.1523-1755.1999.00271.x
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发表时间：
1999-02
影响因子：
19.6
通讯作者：
Shao-Ling Zhang;J. Filep;J. Filep;J. Filep;Thomas C. Hohman;Thomas C. Hohman;Thomas C. Hohman;S. Tang;S. Tang;S. Tang;J. Ingelfinger;J. Ingelfinger;J. Ingelfinger;J. S. Chan;J. S. Chan;J. S. Chan
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作者：
Shao-Ling Zhang;J. Filep;J. Filep;J. Filep;Thomas C. Hohman;Thomas C. Hohman;Thomas C. Hohman;S. Tang;S. Tang;S. Tang;J. Ingelfinger;J. Ingelfinger;J. Ingelfinger;J. S. Chan;J. S. Chan;J. S. Chan
背景临床研究表明血管紧张素转换酶（ACE）抑制剂或血管紧张素II（Ang II）受体拮抗剂可减少糖尿病患者的蛋白尿，延缓糖尿病肾病的进展，提示Ang II在糖尿病肾病的发生发展中起重要作用。我们以前曾报道过高浓度葡萄糖刺激负鼠肾（OK）近端肾小管细胞血管紧张素原（ANG）基因的表达。我们推测D（+）-葡萄糖对肾近曲小管细胞ANG基因表达的刺激作用是通过甘油二酯（diacylglycerol，DAG）的从头合成和蛋白激酶C（protein kinase C，PKC）信号转导途径介导的。方法采用单层培养法培养大鼠永生化近端肾小管上皮细胞（IRPTC）。观察葡萄糖对IRPTC中多元醇通路和PKC信号转导通路的激活作用。用特异性放射免疫分析法和逆转录聚合酶链反应法分别测定培养液中免疫反应性大鼠ANG（IR-rANG）和细胞ANG mRNA。结果D（+）-葡萄糖（25 mM）可显著增加IRPTC细胞内山梨醇、果糖、DAG的水平和PKC活性，并增加IR-rANG和ANG mRNA的表达。D（+）-葡萄糖（25 mM）的这些刺激作用被醛糖还原酶抑制剂Tolrestat阻断。PKC抑制剂也抑制D（+）-葡萄糖（25 mM）对IRPTC中IR-rANG表达的刺激作用。添加佛波醇12-肉豆蔻酸酯13-乙酸酯进一步增强了D（+）-葡萄糖（25 mM）对IRPTC中IR-rANG表达的刺激作用，并阻断了托瑞斯他的抑制作用。结论高浓度D（+）-葡萄糖（25 mM）刺激IRPTC中ANG基因表达的作用至少部分是通过PKC信号转导通路激活剂DAG的重新合成介导的。
BACKGROUND Clinical studies have shown that the angiotensin-converting enzyme (ACE) inhibitors or angiotensin II (Ang II) receptor antagonists decrease proteinuria and slow the progression of nephropathy in diabetes, indicating that Ang II plays an important role in the development of nephropathy. We have previously reported that high levels of glucose stimulate the expression of rat angiotensinogen (ANG) gene in opossum kidney (OK) proximal tubular cells. We hypothesized that the stimulatory effect of D(+)-glucose on the expression of the ANG gene in kidney proximal tubular cells is mediated via de novo synthesis of diacylglycerol (DAG) and the protein kinase C (PKC) signal transduction pathway. METHODS Immortalized rat proximal tubular cells (IRPTCs) were cultured in monolayer. The stimulatory effect of glucose on the activation of polyol pathway and PKC signal transduction pathway in IRPTCs was determined. The immunoreactive rat ANG (IR-rANG) in the culture medium and the cellular ANG mRNA were measured with a specific radioimmunoassay and a reverse transcription-polymerase chain reaction assay, respectively. RESULTS D(+)-glucose (25 mM) markedly increased the intracellular levels of sorbitol, fructose, DAG, and PKC activity as well as the expression of IR-rANG and ANG mRNA in IRPTCs. These stimulatory effects of D(+)-glucose (25 mM) were blocked by an inhibitor of aldose reductase, Tolrestat. PKC inhibitors also inhibited the stimulatory effect of D(+)-glucose (25 mM) on the expression of the IR-rANG in IRPTCs. The addition of phorbol 12-myristate 13-acetate further enhanced the stimulatory effect of D(+)-glucose (25 mM) on the expression of the IR-rANG in IRPTCs and blocked the inhibitory effect of Tolrestat. CONCLUSION These studies suggest that the stimulatory effect of a high level of D(+)-glucose (25 mM) on the expression of the ANG gene in IRPTCs is mediated, at least in part, via the de novo synthesis of DAG, an activator of PKC signal transduction pathway.