OSTEOPONTIN GENE-EXPRESSION AND PROTEIN-SYNTHESIS IN CULTURED RAT MESANGIAL CELLS

It is controversial whether osteopontin (OP) is expressed in glomeruli and involved in glomerular diseases. We examined whether the OP expre ssion is present at gene and protein levels in cultured rat mesangial cells (MCs). Northern blotting revealed a 1.7 kb OP-mRNA expression in MCs. Petal calf serum (FCS) and TNF-alpha increased OP gene expressio n in serum-starved MCs by 2.7- and 1.8-fold over 24- and 12-hour perio ds, respectively. PDGF, IL-1 beta, and TGF-beta had little effect on O P gene expression. Western blotting detected the OP protein expression (69 kDa). PCS and TNF-alpha increased OP protein expression in serum- starved MCs over 48- and 24-hour periods, respectively. The present st udy clearly demonstrated the expression of OP gene and protein in cult ured rat MCs. Increased OP production under serum or TNF-alpha stimula tion suggests that intraglomerular OP may contribute to the developmen t of glomerular diseases. (C) 1997 Academic Press.