Modulation of Kv1.3 channels by protein kinase A I in T lymphocytes is mediated by the disc large 1-tyrosine kinase Lck complex

Zerrin Kuras, Vladimir Kucher, Scott M. Gordon, Lisa Neumeier, Ameet A. Chimote, Alexandra H. Filipovich, Laura Conforti

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

The cAMP/PKA signaling system constitutes an inhibitory pathway in T cells and, although its biochemistry has been thoroughly investigated, its possible effects on ion channels are still not fully understood. Kv1.3 channels play an important role in T-cell activation, and their inhibition suppresses T-cell function. It has been reported that PKA modulates Kv1.3 activity. Two PKA isoforms are expressed in human T cells: PKAI and PKAII. PKAI has been shown to inhibit T-cell activation via suppression of the tyrosine kinase Lck. The aim of this study was to determine the PKA isoform modulating Kv1.3 and the signaling pathway underneath. 8-Bromoadenosine 3′,5′-cyclic monophosphate (8-BrcAMP), a nonselective activator of PKA, inhibited Kv1.3 currents both in primary human T and in Jurkat cells. This inhibition was prevented by the PKA blocker PKI6-22. Selective knockdown of PKAI, but not PKAII, with siRNAs abolished the response to 8-BrcAMP. Additional studies were performed to determine the signaling pathway mediating PKAI effect on Kv1.3. Overexpression of a constitutively active mutant of Lck reduced the response of Kv1.3 to 8-Br-cAMP. Moreover, knockdown of the scaffolding protein disc large 1 (Dlg1), which binds Kv1.3 to Lck, abolished PKA modulation of Kv1.3 channels. Immunohistochemistry studies showed that PKAI, but not PKAII, colocalizes with Kv1.3 and Dlg1 indicating a close proximity between these proteins. These results indicate that PKAI selectively regulates Kv1.3 channels in human T lymphocytes. This effect is mediated by Lck and Dlg1. We thus propose that the Kv1.3/Dlg1/Lck complex is part of the membrane pathway that cAMP utilizes to regulate T-cell function.

Original languageEnglish
Pages (from-to)C1504-C1512
JournalAmerican Journal of Physiology - Cell Physiology
Volume302
Issue number10
DOIs
StatePublished - May 15 2012

Keywords

  • Jurkat
  • Protein kinase A
  • T cell signaling

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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