Hayashi K, Osada S, Shofuda K, Horikoshi S, Shirato I, Tomino Y
Department of Medicine, Juntendo University School of Medicine, Tokyo, Japan.
J Am Soc Nephrol. 1998 Dec;9(12):2262-71. doi: 10.1681/ASN.V9122262.
Matrix metalloproteinase-2 (MMP-2, gelatinase A) is involved in the inflammatory and sclerotic events of glomerular diseases. Newly identified membrane-type matrix metalloproteinases (MT-MMP) have been shown to activate specifically proMMP-2. To date, several types of MT-MMP have been cloned; however, their expressions in glomerular diseases have not been evaluated. To investigate the role of MT-MMP in glomerular diseases, the glomerular gene expression and enzymatic activity of MT-MMP were examined during the time course of nephritis induced in rats by anti-Thy1.1 antibody injection. Both MT1-MMP and MMP-2 mRNA expression increased prominently 5 and 10 d after anti-Thy1.1 antibody injection and decreased thereafter, as assayed by semiquantitative reverse transcription-PCR. In contrast, there were no remarkable changes in the gene expression of MT2-MMP between normal and diseased tissue, and that of MT3-MMP was not detected in isolated glomeruli by reverse transcription-PCR analysis. The activation of proMMP-2 as analyzed by gelatin zymography correlated with the glomerular MT1-MMP gene expression, suggesting that proMMP-2 was activated by MT1-MMP. Protein and mRNA expression of fibronectin, one of the major mesangial matrix proteins and substrate of MMP-2, were also synchronized with MT1-MMP and MMP-2 expression. In situ hybridization revealed intense MT1-MMP mRNA expression in the proliferating mesangial cells. Interestingly, MT1-MMP gene expression exhibited a similar distribution as alpha-smooth muscle actin expression, which was closely associated with mesangial phenotypic change. These results suggest that among the newly identified MT-MMP, MT1-MMP may play the central role in activation of proMMP-2. Furthermore, the enhancement of MT1-MMP and MMP-2 expression associated with mesangial phenotypic change may contribute to the development of anti-Thy1.1 antibody-induced glomerulonephritis and remodeling of extracellular matrices.
基质金属蛋白酶-2（MMP-2，明胶酶A）参与肾小球疾病的炎症和硬化过程。新发现的膜型基质金属蛋白酶（MT-MMP）已被证明能特异性激活前MMP-2。迄今为止，已克隆出几种类型的MT-MMP；然而，它们在肾小球疾病中的表达尚未得到评估。为了研究MT-MMP在肾小球疾病中的作用，在通过注射抗Thy1.1抗体诱导大鼠肾炎的过程中，检测了MT-MMP的肾小球基因表达和酶活性。通过半定量逆转录-PCR检测，抗Thy1.1抗体注射后5天和10天，MT1-MMP和MMP-2 mRNA表达显著增加，随后下降。相比之下，正常组织和病变组织之间MT2-MMP的基因表达没有明显变化，通过逆转录-PCR分析在分离的肾小球中未检测到MT3-MMP的基因表达。通过明胶酶谱分析的前MMP-2激活与肾小球MT1-MMP基因表达相关，表明前MMP-2被MT1-MMP激活。纤连蛋白是主要的系膜基质蛋白之一且是MMP-2的底物，其蛋白和mRNA表达也与MT1-MMP和MMP-2表达同步。原位杂交显示增殖的系膜细胞中MT1-MMP mRNA表达强烈。有趣的是，MT1-MMP基因表达呈现出与α-平滑肌肌动蛋白表达相似的分布，后者与系膜表型变化密切相关。这些结果表明，在新发现的MT-MMP中，MT1-MMP可能在前MMP-2激活中起核心作用。此外，与系膜表型变化相关的MT1-MMP和MMP-2表达增强可能有助于抗Thy1.1抗体诱导的肾小球肾炎的发展和细胞外基质的重塑。
