1,25(OH)2-vitamin D3 signal transduction in chick myoblasts involves phosphatidylcholine hydrolysis.

摘要: 1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) rapidly stimulates the biphasic formation of diacylglycerol (DAG) in chick myoblasts. Neomycin (0.5 mM), an inhibitor phosphoinositide hydrolysis, abolished first phase (1 min) but had no effect on second 1,25(OH)2D3-induced DAG peak (5 min). In myoblasts prelabeled with [3H]choline, 1,25(OH)2D3 increased release [3H]choline (maximally at 5 min), a concomitant decrease phosphatidylcholine and absence significant changes phosphocholine. caused increase phosphatidylethanol (PEt) presence 1.5% ethanol. The effects were time- dose-dependent (10(-11) to 10(-8) M) specific as 25OHD3 24,25(OH)2D3 failed accumulate PEt. 12-O-Tetradecanoylphorbol-13-acetate also stimulated PEt formation. combination 12-O-tetradecanoylphorbol-13- acetate was more effective than either compound alone. Neither PKC H7 nor down-regulation blocked hormone-induced were, however, inhibited extracellular Ca2+ (+EGTA) by nifedipine verapamil, whereas ionophore A23187 generation. data support notion that triggers hydrolysis through Ca(2+)-dependent, PKC-independent, phospholipase D-catalyzed mechanism.