蛋白激酶C-βⅠ,βⅡ在糖尿病肾病小鼠肾组织中的分布、表达及替米沙坦对其影响

目的 探讨蛋白激酶C（PKC）-βⅠ,βⅡ在糖尿病肾病（DN）小鼠肾脏中各部位的分布、表达以及血管紧张素受体拮抗剂替米沙坦对其影响。方法 18只小鼠随机分为正常组、DN组和治疗组（TG组）。采用半定量免疫荧光技术检测肾小球内PKC-βⅠ、βⅡ,转化生长因子（TGF-β1）和血管内皮细胞生长因子（VEGF）的表达情况,激光共聚焦及免疫印迹技术检测PKC-βⅠ,βⅡ在肾组织中的分布与表达。结果 与正常组相比,DN小鼠近曲小管上皮细胞腔膜侧PKC-βⅠ,βⅡ的表达较强,而皮质和内髓集合管上皮细胞PKC-βⅡ的表达消失;DN小鼠肾皮质和外髓PKC-β1的表达量较多（P〈0．01）,而肾皮质内PKC-βⅡ的表达则明显较低（P〈0．01）。半定量免疫荧光进一步表明,PKC-βⅠ、TGF-β1和VEGF在DN小鼠肾小球内的表达量明显高于正常组（分别上调0．48、0．20和0．24倍,均P〈0．01）,而PKC-βⅡ的表达则下调0．27倍（P〈0．05）,其中PKC．31的表达与TGF．31呈正相关（r=0．649,P=0．030）而与VEGF无关（r=0．387,P=0．079）,PKC-βⅡ的表达与TGF-β1、VEGF均无关。替米沙坦能部分纠正上述变化。结论 （1）DN小鼠肾组织中PKC-βⅠ、βⅡ的表达和分布发生变化,提示它们参与DN近曲小管功能改变,其中PKC-β1可能通过影响肾小球TGF-β1的表达参与DN肾小球的肥大。（2）DN时肾素血管紧张素系统的活性增加可能是PKC-βⅠ,βⅡ异常激活的重要原因,替米沙坦可能通过部分改善PKC-βⅠ,βⅡ的表达来实现其肾脏保护作用。

Protein kinase C-betaI, betaII in mouse diabetic nephropathy kidney and its relation to nephroprotective actions of the angiotensin receptor blocker telmisartan

OBJECTIVE: To investigate the localization and expression of protein kinase C (PKC)-betaI, betaII in diabetic nephropathy (DN) mouse kidney and its relation to angiotensin receptor blocker telmistartan (Micardis). METHODS: Eighteen mice were divided into three groups: normal group, DN group and Micardis-treated group (n = 6, each group). The expression of PKC-betaI, betaII, transforming growth factor- beta 1 (TGF-beta1) and vascular endothelial growth factor (VEGF) in glomeruli was measured by semiquantitative immunofluorescence histochemistry, the localization of PKC-betaI, betaII was detected by confocal immunofluorescence laser scanning microscopy and the expression of PKC-betaI, betaII in renal cortex, outer and inner medulla were evaluated by semiquantitative Western blotting. RESULTS: Compared to normal mice, the expression of PKC-betaI and betaII on apical membrane of proximal tubule epithelial cells of DN mice was significantly increased, whereas the expression of PKC-betaII on cortical and inner medullary collecting duct was decreased. Western blotting detected increasing expression of PKC-betaI in the renal cortex and outer medulla (P < 0.01), and decreasing expression of PKC-betaII in renal cortex of DN mice (P < 0.01). Enhanced expression of PKC-betaI as well as TGF-beta1 and VEGF (P < 0.01) were shown in the glomeruli of DN mice, where the expression of PKC-betaII was decreased (P < 0.05). Meanwhile, PKC-betaI exhibited a positive correlation to TGF-beta1 (r = 0.649, P = 0.030), but no correlation to VEGF (r = 0.387, P = 0.079). Micardis could partly attenuate above changes. CONCLUSION: The localization and expression of PKC-betaI, betaII are altered in DN mice, PKC-betaI, betaII may change the function of proximal tubule and PKC-betaI may contribute to glomerular hypertrophy through influencing the expression of glomerular TGF-beta1. Treatment with Micardis can partly improve the abnormal expression and distribution of PKC-betaI, betaII in kidneys of DN mice, which suggests that renin-angiotensin-system is implicated in the pathogenesis of DN by regulating the expression and activation of PKC-betaI, betaII isoforms.