Ca2+/calmodulin-dependent protein kinase II (CaMKII) regulates cardiac sodium channel NaV1.5 gating by multiple phosphorylation sites

Nicole M. Ashpole, Anthony W. Herren, Kenneth S Ginsburg, Joseph D. Brogan, Derrick E. Johnson, Theodore R. Cummins, Donald M Bers, Andy Hudmon

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121 Scopus citations


The cardiac Na+ channel NaV1.5 current (I Na) is critical to cardiac excitability, and altered INa gating has been implicated in genetic and acquired arrhythmias. Ca 2+/calmodulin-dependent protein kinase II (CaMKII) is up-regulated in heart failure and has been shown to cause INa gating changes that mimic those induced by a point mutation in humans that is associated with combined long QT and Brugada syndromes. We sought to identify the site(s) on NaV1.5 that mediate(s) the CaMKII-induced alterations in I Na gating.Weanalyzed both CaMKII binding and CaMKII-dependent phosphorylation of the intracellularly accessible regions of NaV1.5 using a series of GST fusion constructs, immobilized peptide arrays, and soluble peptides. A stable interaction between δC-CaMKII and the intracellular loop between domains 1 and 2 of NaV1.5 was observed. This region was also phosphorylated by δC-CaMKII, specifically at the Ser-516 and Thr-594 sites. Wild-type (WT) and phosphomutant hNa V1.5 were co-expressed with GFP-δC-CaMKII in HEK293 cells, and INa was recorded. As observed in myocytes, CaMKII shifted WT INa availability to a more negative membrane potential and enhanced accumulation of INa into an intermediate inactivated state, but these effects were abolished by mutating either of these sites to non-phosphorylatable Ala residues. Mutation of these sites to phosphomimetic Glu residues negatively shifted INa availability without the need for CaMKII. CaMKII-dependent phosphorylation of NaV1.5 at multiple sites (including Thr-594 and Ser-516) appears to be required to evoke loss-of-function changes in gating that could contribute to acquired Brugada syndrome-like effects in heart failure.

Original languageEnglish (US)
Pages (from-to)19856-19869
Number of pages14
JournalJournal of Biological Chemistry
Issue number24
StatePublished - Jun 8 2012

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology
  • Medicine(all)


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