Regulation of osteopontin expression in rat mesangial cells

Hypercellularity and accumulation of extracellular matrix are common responses of renal glomeruli to inflammatory stimuli. Using the differential display approach, we compared the gene expression patterns of proliferating and differentiating rat mesangial cells in two- and three-dimensional cultures. Osteopontin, an extracellular matrix protein, was found to be transcribed, synthesized, and secreted by rat mesangial cells. Osteopontin transcription was not associated with cell proliferation and was found to be FCS-inducible in proliferating cells. Osteopontin expression was independent of exogenously supplied FCS in differentiating cells. The presented data indicate that osteopontin is differentially regulated in proliferating and differentiating mesangial cells.