[TGF-beta gene expression in mesangial cells].

TGF-beta recently has been shown to inhibit mesangial cell growth and to stimulate mesangial matrix synthesis by mesangial cells. 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 addition of 17% FCS and TPA, one of the phorbol esters, although it is also reported by others that the mRNA expression was stimulated by PDGF, EGF, or high glucose. Bioassay and immunoblot analysis showed that mesangial cells produce and secrete substantial amounts of TGF-beta but mostly in latent forms. Moreover, addition of anti-TGF-beta neutralizing antibodies augmented mesangial cell growth, indicating that the secreted TGF-beta exerts a growth-inhibitory action on themselves. Thus, TGF-beta may function as an autocrine factor in mesangial cells, and it is suggested that mesangial cells may play an important role in the pathogenesis of glomerulopathy.