Analyses for mechanisms of progression of kidney diseases by proteinuria

我们已经报道了蛋白尿诱导肾脏中脑特定蛋白--胶质细胞成熟因子-β的表达(Latiney Int2002)。它导致对氧化损伤的脆弱性，导致培养的肾近端小管细胞(T.Biol.化学，2003)。为了分析GMF表达的病理生理作用，我们构建了表达GMF的转基因小鼠(GMF-TG)和诱导的缺血再灌注(IR)损伤。实时荧光定量聚合酶链式反应显示GMF-TG在肾脏中的表达比野生型小鼠(C57BL/6)高约8倍。采用原位末端标记法检测肾组织中的细胞凋亡。结果表明，GMF-TG大鼠肾脏TUNEL阳性细胞明显增多，提示GMF表达也可诱导体内细胞凋亡。因此，我们推测I/R损伤对GMF-TG小鼠肾脏的损伤可能比对野生型小鼠肾脏的损伤更严重。右肾切除术后缺血性损伤的…表现夹闭左肾动、静脉16min后，上述指标明显升高。令人惊讶的是，在再灌注24小时后，转基因小鼠的血清肌酐水平显著低于正常小鼠(转基因转基因小鼠：0.611±0.07 mg/d1比正常小鼠：0.841±0.19 mg/d1，p&lt；0.05，n=5和6)。实时荧光定量聚合酶链式反应显示，正常肾组织和GMF-TG肾组织中p21、PAI-1和CTGF的表达在诱导I/R损伤前差异无统计学意义。野生型小鼠肾脏I/R损伤后24小时，P21、PAI-1和CTGF表达上调(P21：60.3±12.4，PAI-1：90.6±18.2，CTGF：4.9±1.6倍；n=4)。而GMF-TG小鼠肾脏1/R后24小时各基因表达水平较正常小鼠显著降低(p21：23.3±4.1，PAI-1：39.2±8.4，CTGF：2.4±0.3；n=4)。结论：GMF在体内的表达可能对I/R损伤具有保护作用，但由于其在体外易受氧化损伤而导致细胞凋亡。较少

We have reported that proteinuria induced the expression of brain specific protein, glia maturation factor-β (GMF) in the kidney (latiney Int 2002). It caused vulnerability to oxidative injury, resulting in apoptosis in cultured renal proximal tubular cells (T. Biol. Chem., 2003). To analyze the pathophysiological roles of GMF expression, we constructed transgenic mice expressing GMF (GMF-TG) and induced ischemia-reperfusion (IR) injury.The real-time PCR revealed that the expression of GMF in the kidney of GMF-TG was increased approximately eight times higher than that in wild type mice (C57BL/6) kidney. We performed Tunel assay to evaluate apoptotic cells in the kidney. It demonstrated that Tunel positive cells were significantly increased in the kidney of GMF-TG, indicating that GMF expression induced apoptosis in vivo, too. Thus, we hypothesized that I/R injury might cause severer damages in GMF-TG mice kidney than in wild type mice kidney. After right nephrectomy, ischemic injury w … More as induced by clamping of left renal artery and vein for 16 min. Surprisingly, serum creatinine levels were significantly low in GMF-TG compared to in normal mice (GMF-TG:0.611±0.07 mg/d1 versus normal:0.841±0.19 mg/d1, p<0.05, n=5 and 6, respectively) at 24hrs after reperfusion. Real-time PCR demonstrated that the expression of several mRNA such as p21, PAI-1 and CTGF in the normal and GMF-TG kidney before induction of I/R injury showed no significant differences. P21, PAI-1 and CTGF expression was up-regulated 24hr after I/R injury in wild type mice kidney (p21:60.3±12.4, PAI-1:90.6±18.2, CTGF:4.9±1.6 fold increases; n=4). It, however, was significantly decreased in GMF-TG kidney (p21:23.3±4.1, PAI-1:39.2±8.4, CTGF:2.4±0.3 fold increases; n=4) compared to those in normal mice at 24hr after 1/R. Data are provided as fold increase of each gene expression in wild type and GMF-TG mice kidney without I/R injury.Conclusion: The data indicated that GMF expression in vivo might have protective roles on I/R injury, although its expression resulted in apoptosis because of vulnerability to oxidative injury in vitro. Less