L-type calcium channel α-subunit and protein kinase inhibitors modulate Rem-mediated regulation of current

Shawn M. Crump, Robert N. Correll, Elizabeth A. Schroder, William C. Lester, Brian S. Finlin, Douglas A. Andres, Jonathan Satin

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Cardiac voltage-gated L-type Ca channels (CaV) are multiprotein complexes, including accessory subunits such as CaVβ2 that increase current expression. Recently, members of the Rad and Gem/Kir-related family of small GTPases have been shown to decrease current, although the mechanism remains poorly defined. In this study, we evaluated the contribution of the L-type Ca channel α-subunit (CaV1.2) to Ca Vβ2-Rem inhibition of Ca channel current. Specifically, we addressed whether protein kinase A (PKA) modulation of the Ca channel modifies CaVβ2-Rem inhibition of Ca channel current. We first tested the effect of Rem on CaV1.2 in human embryonic kidney 293 (HEK-293) cells using the whole cell patch-clamp configuration. Rem coexpression with Ca V1.2 reduces Ba current expression under basal conditions, and CaVβ2a coexpression enhances Rem block of CaV1.2 current. Surprisingly, PKA inhibition by 133 nM H-89 or 50 μM Rp-cAMP-S partially relieved the Rem-mediated inhibition of current activity both with and without CaVβ2a. To test whether the H-89 action was a consequence of the phosphorylation status of CaV1.2, we examined Rem regulation of the PKA-insensitive CaV1.2 serine 1928 (S1928) to alanine mutation (CaV1.2-S1928A). CaV1.2-S1928A current was not inhibited by Rem and when coexpression with CaVβ2a was not completely blocked by Rem coexpression, suggesting that the phosphorylation of S1928 contributes to Rem-mediated Ca channel modulation. As a model for native Ca channel complexes, we tested the ability of Rem overexpression in HIT-T15 cells and embryonic ventricular myocytes to interfere with native current. We find that native current is also sensitive to Rem block and that H-89 pretreatment relieves the ability of Rem to regulate Ca current. We conclude that Rem is capable of regulating L-type current, that release of Rem block is modulated by cellular kinase pathways, and that the CaV1.2 COOH terminus contributes to Rem-dependent channel inhibition.

Original languageEnglish
Pages (from-to)H1959-H1971
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number4
StatePublished - 2006


  • Calcium imaging
  • Cardiac myocyte
  • Heart development
  • Insulin-secreting cell
  • Monomeric GTPase
  • Rad and Gem/Kir-related family

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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