Ongoing protein synthesis needed for 1,25-(OH)2D3-mediated rapid increase of cyclic GMP in human skin fibroblasts.

Recently we reported that 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) through interaction with its specific receptor rapidly (within 1 min) stimulated intracellular cGMP production in cultured human skin fibroblasts. Here we show that this effect of 100 nM 1,25-(OH)2D3 is prevented by brief (30 min) inhibition of RNA synthesis (with actinomycin D or alpha-amanitin) or by brief inhibition of protein synthesis (with cycloheximide or diphtheria toxin). The protein synthesis inhibitors also blocked stimulation of cGMP by other steroids (testosterone or dexamethasone at 100 nM) but did not block cGMP stimulation by sodium nitroprusside. Since the time for the 1,25-(OH)2D3 receptor to increase cGMP seems too short to require de novo protein synthesis, we conclude that the 1,25-(OH)2D3 receptor acts together with rapidly turning over protein(s) to stimulate cGMP synthesis.