Kaname S, Uchida S, Ogata E, Kurokawa K
Fourth Department of Internal Medicine, University of Tokyo Faculty of Medicine, Japan.
Kidney Int. 1992 Dec;42(6):1319-27. doi: 10.1038/ki.1992.423.
Transforming growth factor-beta (TGF-beta) recently has been shown to modulate mesangial cell growth and to stimulate mesangial matrix synthesis by mesangial cells. Here we examined whether mesangial cells expressed TGF-beta mRNA and secreted mature TGF-beta, and we investigated the role of TGF-beta in mesangial cell growth. Cultured rat mesangial cells expressed 2.5 kb TGF-beta mRNA, and removal of fetal calf serum (FCS) for two days decreased the TGF-beta mRNA level, which was then stimulated by re-addition of 17% FCS reaching the maximum at nine hours. 12-O-tetradecanoyl phorbol-13-acetate (TPA), one of the phorbol esters, markedly increased the mRNA level and reached the maximum at six or nine hours. Immunoblot analysis of the conditioned media using specific anti-TGF-beta 1 antibodies revealed single 12.5 kDa proteins, the size compatible with mature TGF-beta subunits. By means of bioassay using CCL-64 cell line, TGF-beta production rate by mesangial cells was estimated to be 22.1 +/- 6.5 (mean +/- SD) ng/10(6) cells/24 hours, 96% of which was in latent forms. Exogenously added TGF-beta inhibited mesangial cell growth at 10 pM or higher. Moreover, addition of anti-TGF-beta neutralizing antibodies augmented mesangial cell growth, indicating that the secreted TGF-beta actually exerted a growth-inhibitory action. In summary, mesangial cells produce and secrete substantial amounts of TGF-beta but mostly in latent forms, and the secreted TGF-beta may regulate mesangial cell growth and differentiation. We conclude that TGF-beta may function as an autocrine factor in mesangial cells.
转化生长因子-β（TGF-β）最近已被证明可调节系膜细胞生长，并刺激系膜细胞合成系膜基质。在此，我们研究了系膜细胞是否表达TGF-β mRNA并分泌成熟的TGF-β，并探讨了TGF-β在系膜细胞生长中的作用。培养的大鼠系膜细胞表达2.5 kb的TGF-β mRNA，去除胎牛血清（FCS）两天会降低TGF-β mRNA水平，然后重新添加17% FCS可刺激该水平升高，在9小时时达到最大值。佛波酯之一的12-O-十四酰佛波醇-13-乙酸酯（TPA）可显著提高mRNA水平，并在6或9小时时达到最大值。使用特异性抗TGF-β1抗体对条件培养基进行免疫印迹分析，显示出单一的12.5 kDa蛋白，其大小与成熟的TGF-β亚基相符。通过使用CCL-64细胞系的生物测定法，估计系膜细胞的TGF-β产生率为22.1±6.5（平均值±标准差）ng/10(6)个细胞/24小时，其中96%为潜伏形式。外源添加的TGF-β在10 pM或更高浓度时可抑制系膜细胞生长。此外，添加抗TGF-β中和抗体可增强系膜细胞生长，表明分泌的TGF-β实际上发挥了生长抑制作用。总之，系膜细胞产生并分泌大量的TGF-β，但大多为潜伏形式，分泌的TGF-β可能调节系膜细胞的生长和分化。我们得出结论，TGF-β可能在系膜细胞中作为自分泌因子发挥作用。
