LY294002抑制PI3K/Akt信号通路阻断地塞米松降尿蛋白的作用

目的通过活体阿霉素（ADR）大鼠肾病模型探讨受地塞米松及LY294002影响的PI3K/Akt信号通路以及下游分子Bad的表达、尿蛋白变化相关性及其意义。方法应用随机数表法将SD大鼠分为正常对照组（NC组），阿霉素肾病组（ADR组），阿霉素+地塞米松治疗组（DEX组），阿霉素+地塞米松+LY294002干预组（LY294002组）。分别于第7、14、28天进行24 h尿蛋白定量检测；Western Blot检测肾皮质p-Akt、Akt和Bad蛋白表达水平，Q-PCR检测肾皮质Bad mRNA表达水平。结果ADR组蛋白尿持续增加，p-AKT/AKT比值下降和Bad蛋白表达上调、Bad-mRNA表达增加，较正常NC组有统计学差异（P<0.05）；DEX组尿蛋白明显减少，p-AKT/AKT 比值升高和Bad 蛋白表达下调、Bad mRNA 表达减少，与NC 组无统计学差异（P>0.05）；LY294002组的尿蛋白无减少，p-AKT/AkT比值下降和Bad蛋白表达上调、Bad mRNA表达增加，与DEX组有显著性统计学差异（P<0.05）。结论地塞米松通过激活PI3K/Akt信号通路，下调其下游分子Bad的表达，减少阿霉素肾病大鼠尿蛋白；LY294002干预后可抑制该信号通路，阻断地塞米松减少尿蛋白的作用。这些结果表明PI3K/Akt信号通路是激素减少尿蛋白的信号传导机制之一。

LY294002 blocks the effect of dexamethasone in reducing urine protein in rats by inhibiting PI3K/Akt signaling pathway

Objective To investigate the involvement of PI3K/Akt signaling pathway in the changes of urine protein in adriamycin-induced nephropathic rats treated with dexamethasone and LY294002 (a PI3K inhibitor).Methods SD rats were randomized into normal control group,ariamycin-induced nephropathy group (ADR group),ariamycin + dexamethasone group (DEX group),and ADR+DEX+LY294002 group (LY294002 group).On days 7,14 and 28 after the treatments,24-h urine was collected from the rats to analyze the total urine proteins.The renal tissues were obtained on day 28 to examine the expressions of p-AKT,AKT and Bad proteins in the cortical tissues using Western blotting;the expression of Bad mRNA in the cortical tissues was measured by QPCR.Results Urine protein increased progressively in ADR group accompanied by significantly reduced p-AKT/AKT ratio and increased Bad mRNA expression in comparison with those in the normal control group (P＜0.05).Urine protein was obviously reduced in DEX group with comparable p-AKT/AKT ratio and Bad mRNA expression level with those in the control group (P＞0.05).Urine protein showed no significant reduction in LY294002 group,but the p-AKT/AKT ratio was significantly reduced and Bad mRNA expression was increased compared with those in DEX group (P＜0.05).Conclusion Dexamethasone increases the expression of Bad mRNA and reduces urine protein in adriamycin-induced nephropathic rats by activating PI3K/Akt signaling pathway.LY294002 can inhibit PI3K/Akt signaling pathway to block the effect of dexamethasone,suggesting that PI3K/Akt signaling pathwayis one of the signaling pathways that mediate the effect of dexamethasone on proteinuria.