Modulation by 1,25(OH)2-vitamin D3 of the adenylyl cyclase/cyclic AMP pathway in rat and chick myoblasts

Biochim Biophys Acta. 1995 Oct 19;1269(1):91-7. doi: 10.1016/0167-4889(95)00097-c.

Abstract

We have previously reported that the calciotropic hormone 1,25(OH)2-vitamin D3 stimulates influx of Ca2+ into cultured rat and embryonic chick myoblasts via voltage sensitive Ca(2+)-channels. In the present study, we show that this effect of 1,25(OH)2D3 requires the mediation of the adenylylcyclase signalling system since the hormone-dependent Ca2+ influx is abolished by specific inhibitors of adenylylcyclase and protein kinase A and mimicked by forskolin and dibutyryl cAMP. 1,25(OH)2D3-stimulated elevations in cellular cAMP paralleled increases in Ca2+ uptake, further suggesting a coupling of adenylylcyclase activation and calcium influx. Fluoride and GTP gamma S mimicked 1,25(OH)2D3-stimulation of calcium influx while GDP beta S suppressed the effect of the hormone. Cholera toxin and Bordetella pertussis toxin both increased 45Ca2+ uptake in rat and chick myoblasts. The hormone further increased cholera toxin actions, but was unable to modify pertussis toxin-induced 45Ca2+ uptake, suggesting a similar target of action for pertussis toxin and 1,25(OH)2D3. Incubation of microsomal membranes with the sterol (10 nM, 2 min) markedly displaces (-32%) [35S]GTP gamma S binding to the membranes. ADP-ribosylation of the pertussis toxin-sensitive 41 kDa substrate was significantly increased (+40%) in 1,25(OH)2D3-pretreated cells. These results suggest that 1,25(OH)2D3-stimulated influx of Ca2+ into rat and embryonic chick cultured myoblasts sequentially requires inhibition of a pertussis toxin-sensitive G protein, accumulation of cAMP and activation of dihydropyridine-sensitive Ca(2+)-channels through PKA-mediated phosphorylation events.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenylyl Cyclases / metabolism*
  • Animals
  • Calcitriol / pharmacology*
  • Calcium / metabolism*
  • Calcium Channels / metabolism
  • Cells, Cultured
  • Chick Embryo
  • Cyclic AMP / metabolism*
  • GTP-Binding Proteins / metabolism
  • Muscles / metabolism*
  • Rats
  • Second Messenger Systems / drug effects

Substances

  • Calcium Channels
  • Cyclic AMP
  • GTP-Binding Proteins
  • Adenylyl Cyclases
  • Calcitriol
  • Calcium