Bai Yaling, Wang Lizhu, Li Yongqiang, Liu Senyan, Li Jingzi, Wang Haiyan, Huang Haichang
Division of Nephrology, Peking University First Hospital, Beijing, China.
Cell Physiol Biochem. 2006;17(1-2):57-68. doi: 10.1159/000091464. Epub 2006 Feb 7.
Recent evidences have demonstrated an important role for glomerular visceral epithelial cell (podocyte) in the development and progression of diabetic nephropathy. We investigated the high-glucose (HG)-triggered signaling pathway and its role in matrix metalloproteinase (MMP) production in murine podocytes. The activity of 92-kDa (MMP-9) gelatinase, but not of 72 kDa (MMP-2), in an HG medium significantly increased during incubation of 2 to 3 days and decreased during incubation of more than 5 days revealed by Gelatin zymography. Opposite to the increases in MMP-9 activity, HG medium produced significant decreases in the protein levels of alpha5(IV) collagen. Changes in MMP-9 activity were associated with the same pattern as MMP-9 mRNA levels in podocytes exposed to HG media. HG medium rapidly activated ERK1/2 MAPK in podocytes. Moreover, ERK1/2 activation was required for HG-induced enhancement of MMP-9 activity and a decrease in the level of alpha5(IV) collagen. HG incubation rapidly induced an increase in the nuclear accumulation of Ets-1 protein. Blocking the ERK pathway suppressed HG-induced expression and nuclear accumulation of transcriptional factor Ets-1, and MMP-9 mRNA expression. We suggest that short- or long-term exposure to HG concentrations increases or decreases MMP-9 production and alpha5(IV) collagen expression in podocytes, this may contribute to the GBM abnormality caused by an imbalance in extracellular matrix (ECM) synthesis and degradation, and may play a critical role in the pathogenesis of proteinuria in diabetic nephropathy.
最近的证据表明肾小球脏层上皮细胞（足细胞）在糖尿病肾病的发生和发展中起重要作用。我们研究了高糖（HG）触发的信号通路及其在小鼠足细胞中基质金属蛋白酶（MMP）产生中的作用。通过明胶酶谱法显示，在HG培养基中培养2至3天时，92 kDa（MMP-9）明胶酶的活性显著增加，而72 kDa（MMP-2）的活性未增加；培养超过5天时，MMP-9活性降低。与MMP-9活性增加相反，HG培养基使α5（IV）胶原的蛋白水平显著降低。MMP-9活性的变化与暴露于HG培养基的足细胞中MMP-9 mRNA水平的变化模式相同。HG培养基可快速激活足细胞中的ERK1/2 MAPK。此外，HG诱导的MMP-9活性增强和α5（IV）胶原水平降低需要ERK1/2激活。HG孵育可迅速诱导Ets-1蛋白核蓄积增加。阻断ERK通路可抑制HG诱导的转录因子Ets-1的表达和核蓄积以及MMP-9 mRNA表达。我们认为，短期或长期暴露于HG浓度会增加或降低足细胞中MMP-9的产生和α5（IV）胶原的表达，这可能导致细胞外基质（ECM）合成与降解失衡引起的肾小球基底膜异常，并可能在糖尿病肾病蛋白尿的发病机制中起关键作用。
