Vasopressin Stimulates the Induction of Heat Shock Protein 27 and αB-Crystallin via Protein Kinase C Activation in Vascular Smooth Muscle Cells☆

Abstract In the present study, we examined the effect of vasopressin on the induction of the low-molecular-weight heat shock proteins heat shock protein 27 (HSP27) and αB-crystallin in an aortic smooth muscle cell line, A10 cells. Vasopressin induced a time-dependent accumulation of HSP27 and αB-crystallin. The stimulatory effects of vasopressin were dose-dependent over the range 0.1 nmol/L to 0.1 μmol/L. The EC 50 values for vasopressin were 2 (HSP27) and 4 nmol/L (αB-crystallin). Vasopressin induced increases in the levels of the mRNAs for HSP27 and αB-crystallin. 12- O -Tetradecanoylphorbol 13-acetate (TPA), a protein kinase C (PKC)-activating phorbol ester, induced an accumulation of HSP27 (EC 50 , 20 nmol/L) and αB-crystallin (EC 50 , 2 nmol/L). In contrast, 4α-phorbol 12,13-didecanoate, a non-PKC-activating phorbol ester, had no such effect. Staurosporine and calphostin C, inhibitors of PKC, significantly reduced the vasopressin-induced accumulation of HSP27 and αB-crystallin as well as that induced by TPA. BAPTA/AM and TMB-8, inhibitors of intracellular Ca 2+ mobilization, significantly reduced the vasopressin-induced accumulation of HSP27 and αB-crystallin. These results strongly suggest that vasopressin stimulates the induction of HSP27 and αB-crystallin via PKC activation in vascular smooth muscle cells and that this effect of vasopressin is dependent on intracellular Ca 2+ mobilization.