Studies suggesting the participation of protein kinase A in 1, 25(OH)2-vitamin D3-dependent protein phosphorylation in cardiac muscle

J Mol Cell Cardiol. 1998 Feb;30(2):225-33. doi: 10.1006/jmcc.1997.0577.


We have previously established that the secosteroid hormone 1alpha, 25-dihydroxy-vitamin D3 [1,25(OH)2D 3] rapidly stimulates dihydropyridine-sensitive calcium channel-mediated Ca2+ influx in chick cardiac muscle by a non-genomic action which is accompanied by phosphorylation of microsomal proteins. In the present study, we investigated the participation of the cyclic AMP/protein kinase A (PKA) signalling pathway in hormone-induced changes on protein phosphorylation in chick heart tissue. A major increase in the phosphorylation of a microsomal protein of 45 kDa, and, to a lesser extent, of a protein of 70 kDa, was observed after incubation with [gamma-32P]ATP of membranes isolated from heart thin slices (HTS) pretreated for 1-5 min with 1,25(OH)2D3. This effect was dose- and time-dependent, reaching a maximum after 3 min and at the physiological concentrations of 10(-10) and 10(-11) M. 1,25(OH)2D3 steadily increased cellular cAMP levels as a function of the dose (10( -12)-10(-9) M). The specific agonist of PKA, Sp-cAMPS and the PKA catalytic subunit stimulated the phosphorylation of the same membrane proteins as the hormone. The 1alpha,25-dihydroxy-vitamin D3-dependent changes in microsomal protein phosphorylation were diminished by the specific PKA inhibitor, Rp-cAMPS. In addition, the PKA activity ratio (-cAMP/+cAMP) increased 60% above the control after treatment of HTS with 10(-11) M 1,25(OH)2D3. The data obtained clearly indicate that activation of the cAMP/PKA signalling pathway mediates the stimulation of protein phosphorylation by 1alpha, 25-dihydroxy-vitamin D3 in chick cardiac muscle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcitriol / metabolism*
  • Calcitriol / pharmacology
  • Chickens
  • Cyclic AMP / metabolism
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Heart / drug effects
  • In Vitro Techniques
  • Microsomes / drug effects
  • Microsomes / metabolism
  • Muscle Proteins / metabolism*
  • Myocardium / metabolism*
  • Phosphorylation
  • Signal Transduction


  • Muscle Proteins
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases
  • Calcitriol