Characterization of a glomerular epithelial cell metalloproteinase as matrix metalloproteinase-9 with enhanced expression in a model of membranous nephropathy
Characterization of a glomerular epithelial cell metalloproteinase as matrix metalloproteinase-9 with enhanced expression in a model of membranous nephropathy
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DOI：
10.1172/jci118502
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发表时间：
1996-02-15
影响因子：
15.9
通讯作者：
Lovett, DH
中科院分区：
文献类型：
--
作者：
McMillan, JI;Riordan, JW;Lovett, DH
肾小球内脏上皮细胞在肾小球细胞外基质的生理性更新和病理性破坏中的作用在很大程度上尚未被探索。本研究表明，由培养的大鼠内脏肾小球上皮细胞分泌的98 kD中性蛋白酶是一种以潜伏形式分泌的钙、锌依赖性酶。此外，该蛋白质是高度糖基化的，并表现出对I型明胶、IV型胶原明胶和纤连蛋白的蛋白水解活性。与92 kD人基质金属蛋白酶-9（MMP-9，或明胶酶B）在分子量和底物特异性上的相似性表明了这种活性的同一性，这通过免疫沉淀和北方印迹分析得到证实。分子量的差异（98与92 kD）不是由于种属特异性糖基化模式的差异。因为培养的大鼠腹腔巨噬细胞分泌MMP-9作为92-kD酶。此外，人MMP-9 cDNA转染到大鼠肾小球上皮细胞产生98-kD的产品。使用特异性单克隆抗MMP-9抗体和MMP-9 mRNA的原位逆转录（ISRT）分析，在体内评价该酶的表达。正常大鼠肾小球表达MMP-9的免疫组化或ISRT染色很少，而被动Heymann肾炎大鼠内脏上皮细胞内MMP-9蛋白和mRNA染色显著增加。MMP-9表达的时间模式与该模型相关的蛋白尿期相关，表明GEC MMP-9表达和肾小球毛细血管通透性变化之间可能存在因果关系。
The role of the glomerular visceral epithelial cell in the physiologic turnover and pathologic breakdown of the glomerular extracellular matrix has remained largely unexplored. Tn this study a 98-kD neutral proteinase secreted by cultured rat visceral glomerular epithelial cells was shown to be a calcium, zinc-dependent enzyme secreted in latent form. In addition, the protein was heavily glycosylated and demonstrated proteolytic activity against Type I gelatin, Type TV collagen gelatin, and fibronectin. The similarity in molecular mass and substrate specificities to the 92-kD human matrix metalloproteinase-9 (MMP-9, or gelatinase B) suggested the identity of this activity, which was confirmed by immunoprecipitation and Northern blot analysis. The differences in molecular mass (98 vs. 92 kD) were not due to species-specific differences in glycosylation patterns. since cultured rat peritoneal macrophages secreted MMP-9 as a 92-kD enzyme. Furthermore, transfection of the human MMP-9 cDNA into rat glomerular epithelial cells yielded the 98-kD product. Using a specific monoclonal anti-MMP-9 antibody and in situ reverse transcription (ISRT) analysis of MMP-9 mRNA, the expression of this enzyme was evaluated in vivo. Normal rat glomeruli expressed little immunohistochemical or ISRT staining for MMP-9, while in rats with passive Heymann nephritis there was a major increase in MMP-9 protein and mRNA staining within the visceral epithelial cells. The temporal patterns of MMP-9 expression correlated with the period of proteinuria associated with this model, suggesting that a causal relationship may exist between GEC MMP-9 expression and changes in glomerular capillary permeability.