肌醇加氧酶在糖尿病肾病发病机制中的作用

Expression of myoinositol oxygenase in renal proximal tubular epithelial cells under high glucose ambience

[目的]研究高糖环境下大鼠肾近曲小管上皮细胞肌醇加氧酶(myoinositol oxygenase,MIOX)的表达及糖尿病肾病大鼠体内肌醇耗竭的机制。[方法]体外培养大鼠近曲肾小管上皮细胞株(NRK-52E),将其分为正常对照组(NG)、高糖组(HG)和渗透浓度对照组(MG),并分别于12、24、48、72 h应用RT-PCR法检测MIOX的mRNA表达,免疫荧光细胞化学法检测其蛋白的表达。[结果]HG组MIOXmNA与蛋白表达水平在12 h出现升高,二者分别在24 h与48 h达高峰。NG组的MIOXmRNA及蛋白表达水平各时间点差异无显著性意义(P>0.05);与NG组和MG组相比,HG组MIOX的mRNA及蛋白表达均明显升高(P<0.01)。MG组明显高于NG组(P<0.05)。[结论]高糖能促进大鼠肾近曲小管上皮细胞肌醇加氧酶(MIOX)的表达,并可能通过MIOX的形成增加介导肌醇的耗竭,提示MIOX参与了糖尿病肾病的发生发展。

[ Objective ] To investigate the influence of high glucose on myoinositol oxygenase （MIOX） mRNA and protein expression in rat renal proximal tubular epithelial cells, and to explain the mechanism for the depletion of myoinositol in diabetic nephropathy rats. [ Method ] Rat renal proximal tubular epithelial cells were cultured in vitro, and divided into normal glucose group （ NG）, high glucose group （HG） and osmotic control group （MG）. The expressions of MIOX mRNA were measured by RTPCR. The proteins were detected by immunofluorescence cytochemisrty technique at 12,24,48,72 h. [Results] The MIOX mRNA and protein levels were elevated at the end of the 12nd hour, after cells exposed to 25 mmol/1 D - glucose and reached its highest level after 24 and 48 hours respectively. The expression levels of MIOX mRNA and protein were not changed dramatically in NG group （ P 〉 0.05 ）. Compared with NG and MG group, MIOX mRNA and protein expression increased significantly in HG group （P 〈 0.01 ）. Both of mRNA and protein were also significantly higher in MG than in NG group （P 〈 0.05）. [ Conclusion] In response to high glucose, expression of MIOX mRNA and protein in rat renal proximal tubular epithelial cells was upregulated and the high expression of MIOX may mediate the depletion of myoinositol, so MIOX may play a role in the development and progress of diabetic nephropathy.