Effects of glycated type IV collagen on extracellular matrix components synthesis in rat mesangial cells

近年来的研究表明，肾小球蛋白的糖基化在糖尿病肾病的发病机制中起着重要作用。IV型胶原是肾小球细胞外基质的主要成分之一，由于其半衰期长，似乎是蛋白质糖化的主要靶点。糖尿病肾病的特征是系膜基质的积聚。肾小球系膜基质的积累是由于基质成分的产生增加或基质降解减少的结果，最近的研究表明TGF-β在肾小球系膜基质的积累中起着突出的作用。为了阐明IV型胶原糖基化在肾小球硬化形成中的作用，我们研究了IV型胶原糖基化对大鼠系膜细胞基质成分、基质降解酶和TGF-β基因表达的影响。添加GL ...更多信息 糖化IV型胶原蛋白的肾小球系膜细胞引起的α 1（I）胶原蛋白mRNA水平的时间依赖性增加，最大增加发生在48小时。此外，糖化IV型胶原蛋白也导致α 1（IV）胶原蛋白和纤连蛋白的mRNA水平的增加。条件培养基中的明胶溶解活性不受添加糖化IV型胶原的影响。基质金属蛋白酶-2的mRNA水平也没有显示出显着的变化，由糖化IV型胶原。24小时后，糖化IV型胶原诱导TGF-β mRNA水平增加，这先于α 1（I）胶原mRNA水平增加。与抗TGF-β中和抗体共孵育显著降低了由糖化科尔IV诱导的α 1（I）胶原mRNA水平的增加。瞬时转染的肾小球系膜细胞与α 1（I）胶原启动子荧光素酶结构显示，启动子活性显着增加糖化IV型胶原的加入。这些结果表明，糖化IV型胶原诱导基质成分基因表达通过转录激活在肾小球系膜细胞，这些影响是通过诱导TGF-β的表达介导的。少

Recent studies have indicated that increased glycation in glomerular proteins plays an important role in the pathogenesis of diabetic nephropathy. Type IV collagen, one of major components of glomerular extracellular matrix, appears to be a predominant targets for protein glycation because of its long half life. Diabetic nephropathy is characterized by the accumulation of mesangial matrix. Accumulation of mesangial matrix occurs as the result of an increase in production of matrix components or a decrease in matrix degradation, and recent studies indicates a preeminent role for TGF-beta in the accumulation of mesangial matrix. To clarify the role of accumulation of glacycated type IV collagen in the development of glmerular sclerosis, we investigated that the effects of in vitro glycation of type IV collagen on the gene expression of matrix components, matrix-degrading enzyme, and TGF-beta in rat mesangial cells.Type IV collagen was glycated with incubation with glucose. Addition of gl … More ycated type IV collagen to meangial cells caused time dependent increase in the alpha1(I) collagen mRNA levels with maximal increases occurring at 48 hr. Addition of glycated type IV collagen also led to increases in mRNA levels for alpha1(IV) collagen and fibronectin. Gelatinolytic activity in conditioned media was not affected by the addition of glycated type IV collagen. The mRNA levels for matrix metalloproteinase-2 also did not show significant change by the glycated type IV collagen. Glycated type IV collagen induced increase in TGF-beta mRNA levels after 24 hr, which preceded the increase in alpha1(I) collagen mRNA levels. Increase in alpha1(I) collagen mRNA levels induced by glycated coll IV was significantly decreased by the co-incubation with anti-TGF-beta neutralizing antibody. Transient transfections of mesangial cells with alpha1(I) collagen promoter-luciferase constructs showed significant increase in promoter activity by the addition of glycated type IV collagen.These results indicated that glycated type IV collagen induces matrix components gene expression through transcriptional activation in mensangial cells and these effects are mediated in part by the induction of TGF-beta expression. Less