Sodium butyrate-induced structural and functional modifications in proteins of cultured rabbit articular chondrocytes

The effects of sodium butyrate (NaB), a potent growth inhibitory agent, on actin distribution, alkaline phosphatase (AP) activity and protein content were studied in rabbit articular chondrocytes in monolayer culture. When growth of randomly proliferating cells was arrested with NaB, actin stress fibers appeared; at the same time, vimentin-containing intermediate filaments and tubulin-containing microtubules were dispersed. Concomitantly, membrane AP activity and protein content were increased. Such effects support the hypothesis that NaB affects the expression of many proteins by modification of gene expression, probably at the transcriptional level.