Kagami S, Kuhara T, Yasutomo K, Okada K, Löster K, Reutter W, Kuroda Y
Department of Pediatrics, School of Medicine, University of Tokushima, Japan.
Exp Cell Res. 1996 Nov 25;229(1):1-6. doi: 10.1006/excr.1996.0336.
Transforming growth factor-beta (TGF-beta) has been implicated in the pathogenesis of mesangial matrix (MM) accumulation in human and experimental glomerulonephritis. To clarify molecular mechanisms responsible for pathological MM deposition, we examined the effect of TGF-beta on the production of beta1 integrins and on adhesion function of rat mesangial cells (MC). In immunoprecipitation experiments using [35S]methionine-labeled MC, stimulation of MC with TGF-beta for 48 h resulted in an increase in the synthesis of alpha1beta1 (collagen/laminin receptor) and alpha5beta1 (fibronectin receptor) integrins accompanied by increases in the synthesis of their ligands, collagen type I (collagen I), and fibronectin. A time-dependent increase in beta1, alpha1 integrin subunit mRNA peaking 48 h after exposure to TGF-beta was shown by Northern blot analysis. After 48 h of treatment with TGF-beta, MC displayed significant increases in adhesion to fibronectin, collagen I, and laminin as compared to untreated MC. Anti-beta1 antiserum significantly inhibits MC adhesion to fibronectin, collagen I, and laminin. Anti-alpha1 subunit antibody very strongly inhibited adhesion to collagen I and laminin, but not to fibronectin. Synthetic peptides containing RGD sequences specifically blocked adhesion to fibronectin. These data suggest that TGF-beta may promote MM deposition by increasing MC synthesis of both matrix proteins and beta1 integrins which facilitate binding of these proteins to the MC surface and thus enhance their incorporation into MM.
转化生长因子-β（TGF-β）已被证明与人类和实验性肾小球肾炎中系膜基质（MM）积聚的发病机制有关。为了阐明导致病理性MM沉积的分子机制，我们研究了TGF-β对大鼠系膜细胞（MC）β1整合素产生及黏附功能的影响。在用[35S]甲硫氨酸标记的MC进行的免疫沉淀实验中，用TGF-β刺激MC 48小时导致α1β1（胶原/层粘连蛋白受体）和α5β1（纤连蛋白受体）整合素的合成增加，同时其配体I型胶原（胶原I）和纤连蛋白的合成也增加。Northern印迹分析显示，β1、α1整合素亚基mRNA在暴露于TGF-β后48小时达到峰值，并呈时间依赖性增加。用TGF-β处理48小时后，与未处理的MC相比，MC对纤连蛋白、胶原I和层粘连蛋白的黏附显著增加。抗β1抗血清显著抑制MC对纤连蛋白、胶原I和层粘连蛋白的黏附。抗α1亚基抗体非常强烈地抑制对胶原I和层粘连蛋白的黏附，但不抑制对纤连蛋白的黏附。含有RGD序列的合成肽特异性地阻断对纤连蛋白的黏附。这些数据表明，TGF-β可能通过增加MC对基质蛋白和β1整合素的合成来促进MM沉积，这有助于这些蛋白与MC表面结合，从而增强它们掺入MM。
