Evidence for the participation of protein kinase C and 3′,5′-cyclic AMP-dependent protein kinase in the stimulation of muscle cell proliferation by 1,25-dihydroxy-vitamin D3

Teresita Bellido, Susana Morelli, Luis M. Fernández, Ricardo Boland

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Treatment with 1,25-dihydroxy-vitamin D3 (1,25(OH)2D3) (1-12 h, 10-10 M) stimulates DNA synthesis in proliferating myoblasts, with an early response at 2-4 h of treatment followed by a maximal effect at 10 h. To investigate the mechanism involved in the mitogenic action of the hormone we studied the possible activation of intracellular messengers by 1,25(OH)2D3. The initial phase of stimulation of [3H]thymidine incorporation into DNA by the sterol was mimicked by the protein kinase C activator tetradecanoylphorbol acetate (TPA) in a manner which was dose dependent and specific as the inactive analog 4α-phorbol was without effect. Maximal responses to TPA (100 nM) were obtained at 4 h. Staurosporine, a protein kinase C inhibitor, blocked the effect of 1,25(OH)2D3 on myoblast proliferation at 4 h. In addition, a fast (1-5 min) elevation of diacylglycerol levels and membrane-associated protein kinase C activity was observed in response to 1,25(OH)2D3. The adenylate cyclase activator forskolin (20 μM) and dibutyryl-cAMP (50 μM) increased DNA synthesis reproducing the second 1,25(OH)2D3-dependent stimulatory phase at 10 h. Inhibitors of protein kinase A blocked the increase in muscle cell DNA synthesis induced by 1,25(OH)2D3 at 10 h. Significant increases in cyclic AMP levels were detected in myoblasts treated with the sterol for 1-10 h. The calcium channel antagonist nifedipine (5-10 μM) abolished both the effects of 4-h treatment with 1,25(OH)2D3 or TPA and 10-h treatment with 1,25(OH)2D3 or dibutyryl-cAMP. Similar to the calcium channel agonist Bay K8644, 1,25(OH)2D3 stimulated myoblast 45Ca uptake and its effects were blocked by nifedipine. Our results suggest that activation of calcium channels by phosphorylation via protein kinases C and A and is involved in the mitotic response of myoblasts to 1,25(OH)2D3.

Original languageEnglish (US)
Pages (from-to)231-238
Number of pages8
JournalMolecular and Cellular Endocrinology
Volume90
Issue number2
DOIs
StatePublished - Jan 1993
Externally publishedYes

Keywords

  • 1,25-Dihydroxy-vitamin D
  • Calcium channel
  • Cell proliferation
  • Cyclic AMP
  • Muscle
  • Myoblast
  • Protein kinase A
  • Protein kinase C

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology

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