cAMP-dependent regulation of cardiac L-type Ca2+ channels requires membrane targeting of PKA and phosphorylation of channel subunits

Tianyan Gao, Atsuko Yatani, Mark L. Dell'Acqua, Hidenori Sako, Stuart A. Green, Nathan Dascal, John D. Scott, M. Marlene Hosey

Research output: Contribution to journalArticlepeer-review

444 Scopus citations

Abstract

The cardiac L-type Ca2+ channel is a textbook example of an ion channel regulated by protein phosphorylation; however, the molecular events that underlie its regulation remain unknown. Here, we report that in transiently transfected HEK293 cells expressing L-type channels, elevations in cAMP resulted in phosphorylation of the α(1c) and β(2a) channel subunits and increases in channel activity. Channel phosphorylation and regulation were facilitated by submembrane targeting of protein kinase A (PKA), through association with an A-kinase anchoring protein called AKAP79. In transfected cells expressing a mutant AKAP79 that is unable to bind PKA, phosphorylation of the α(1c) subunit and regulation of channel activity were not observed. Furthermore, we have demonstrated that the association of an AKAP with PKA was required for β-adrenergic receptor-mediated regulation of L-type channels in native cardiac myocytes, illustrating that the events observed in the heterologous expression system reflect those occurring in the native system. Mutation of Ser1928 to alanine in the C-terminus of the α(1c) subunit resulted in a complete loss of cAMP-mediated phosphorylation and a loss of channel regulation. Thus, the PKA-mediated regulation of L-type Ca2+ channels is critically dependent on a functional AKAP and phosphorylation of the α(1c) subunit at Ser1928.

Original languageEnglish
Pages (from-to)185-196
Number of pages12
JournalNeuron
Volume19
Issue number1
DOIs
StatePublished - Jul 1997

Bibliographical note

Funding Information:
We thank Dr. H. Masaki for help with preliminary experiments and Cheryl Theiss for expert tissue culture assistance. We also thank Tipu Puri and Brian Gerhardstein for help with Sf9 cell culture and Andy Chien for preparing expression constructs of Ca 2+ channel subunits. This work was supported by NIH grants HL23306 (M. M. H.), GM48231 (J. D. S.), GM54169 (A. Y.), AHA grant-in-aid 93012860 (A. Y.), University of Cincinnati Research Challenge grant (A. Y. and S. A. G.), and an NSF Career Advancement Award (A. Y.).

ASJC Scopus subject areas

  • General Neuroscience

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