高糖对足细胞表达结缔组织生长因子及其受体蛋白的调节

High glucose regulates the expression of connective tissue growth factor and its receptor(low density lipoprotein receptor-related protein) in cultured podocytes

目的:研究长期高糖对体外培养的足细胞表达结缔组织生长因子(CTGF)及其受体———低密度脂蛋白受体相关蛋白(LRP)的影响以及可能涉及的信号途径。方法:以体外培养的小鼠肾小球足细胞为研究对象,应用Western印迹分析技术,检测高糖刺激不同时间对足细胞表达CTGF蛋白的影响。观察高糖对丝裂素激活蛋白激酶(MAPKS)信号途径活化的影响以及MAPKS信号途径在高糖调节足细胞表达CTGF中的作用,同时检测高糖对足细胞CTGF的受体LRP蛋白的影响。结果:体外培养足细胞表达基础水平的CTGF蛋白,高糖刺激2天后足细胞表达CTGF水平开始升高,第4天达高峰,第6天下降,第8天降至对照组水平。正常糖和甘露醇组CTGF蛋白没有明显变化。高糖可以激活足细胞外信号调节激酶(ERK1/2),于刺激30min时ERK1/2即开始活化,6h达高峰,持续至24h,48h接近基础水平。正常糖和甘露醇在各个时间点均不活化ERK1/2。应用ERK1/2活化特异抑制剂PD98059可以消减高糖刺激CTGF表达增加的效应。在各个时间点,长期高糖环境对足细胞CTGF的受体LRP蛋白没有明显作用。结论:短期(2～4d)高糖通过活化ERK1/2信号通路刺激足细胞CTGF的表达,高糖继续培养(6～8d)对足细胞内的CTGF蛋白表达水平没有影响。长期高糖环境对足细胞上CTGF的受体LRP蛋白的表达无影响。

Objective ：To observe the expression of connective tissue growth factor（CTGF） and its receptor- low density lipoprotein receptor-related protein （LRP）, and the relevant signaling pathway for the regulation by long-term high glucose exposure in cultured podocytes. Methods：The effects of high glucose on the expression of CTGF and its receptor LRP were analyzed by western blotting. The activation of mitogen activated protein kinase （ MAPKS ） signaling pathway by high glucose was also examined. Resuits： Basal levels of CTGF were observed in cultured mouse podocytes, the levels of CTGF protein were increased by high glucose medium groups on the 2nd day, reached the peak on the 4th day（ P 〈0.05 ）, began to decline on the 6th day, returned to the basal level on the 8th day（P 〉0.05）. The levels of CTGF expression in normal glucose and mannitol glucose groups did not change markly. High glucose medium induced phosphorylation of ERK1/2 at as early as minute 30, reached the peak at hour 6 ; mainrtained the activity at hours 12 and 24, and declined to the basal level at hour 48. However, phosphorylation of ERK1/2 was not detected in normal glucose and mannitol glucose groups. Blockade of phosphorylation of ERK1/2 with PD98059, a specific ERK1/2 activation inhibitior, did decrease the high glucose-triggered expression of CTGF protein in 4 days. High glucose had no effect on the expression of LRP protein at each time point. Conclusion： Acute high glucose （2 -4 days）stimulated the expression of CTGF protein via ERK1/2-dependent signaling pathway in cultured podocytes, while cultured in high glucose for 6 -8 days, the podocytes did not increase its CTGF level. Long-term high glucose had no effect on the expression of LRP in podocytes.