title: Nav1.5-dependent persistent Na+ influx activates CaMKII in rat ventricular myocytes and N1325S mice.
abstract: Late Na(+) current (I(NaL)) and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) are both increased in the diseased heart. Recently, CaMKII was found to phosphorylate the Na(+) channel 1.5 (Na(v)1.5), resulting in enhanced I(NaL). Conversely, an increase of I(NaL) would be expected to cause elevation of intracellular Ca(2+) and activation of CaMKII. However, a relationship between enhancement of I(NaL) and activation of CaMKII has yet to be demonstrated. We investigated whether Na(+) influx via Na(v)1.5 leads to CaMKII activation and explored the functional significance of this pathway. In neonatal rat ventricular myocytes (NRVM), treatment with the I(NaL) activators anemone toxin II (ATX-II) or veratridine increased CaMKII autophosphorylation and increased phosphorylation of CaMKII substrates phospholamban and ryanodine receptor 2. Knockdown of Na(v)1.5 (but not Na(v)1.1 or Na(v)1.2) prevented ATX-II-induced CaMKII phosphorylation, providing evidence for a specific role of Na(v)1.5 in CaMKII activation. In support of this view, CaMKII activity was also increased in hearts of transgenic mice overexpressing a gain-of-function Na(v)1.5 mutant (N(1325)S). The effects of both ATX-II and the N(1325)S mutation were reversed by either I(NaL) inhibition (with ranolazine or tetrodotoxin) or CaMKII inhibition (with KN93 or autocamtide 2-related inhibitory peptide). Furthermore, ATX-II treatment also induced CaMKII-Na(v)1.5 coimmunoprecipitation. The same association between CaMKII and Na(v)1.5 was also found in N(1325)S mice, suggesting a direct protein-protein interaction. Pharmacological inhibitions of either CaMKII or I(NaL) also prevented ATX-II-induced cell death in NRVM and reduced the incidence of polymorphic ventricular tachycardia induced by ATX-II in rat perfused hearts. Taken together, these results suggest that a Na(v)1.5-dependent increase in Na(+) influx leads to activation of CaMKII, which in turn phosphorylates Na(v)1.5, further promoting Na(+) influx. Pharmacological inhibition of either CaMKII or Na(v)1.5 can ameliorate cardiac dysfunction caused by excessive Na(+) influx.
authors.affiliation: Department of Biology, Gilead Sciences, Palo Alto, California 94304, USA. lina.yao@gilead.com
authors.forename: Lina
authors.initials: L
authors.lastname: Yao
authors.forename: Peidong
authors.initials: P
authors.lastname: Fan
authors.forename: Zhan
authors.initials: Z
authors.lastname: Jiang
authors.forename: Serge
authors.initials: S
authors.lastname: Viatchenko-Karpinski
authors.forename: Yuzhi
authors.initials: Y
authors.lastname: Wu
authors.forename: Dmytro
authors.initials: D
authors.lastname: Kornyeyev
authors.forename: Ryoko
authors.initials: R
authors.lastname: Hirakawa
authors.forename: Grant R
authors.initials: GR
authors.lastname: Budas
authors.forename: Sridharan
authors.initials: S
authors.lastname: Rajamani
authors.forename: John C
authors.initials: JC
authors.lastname: Shryock
authors.forename: Luiz
authors.initials: L
authors.lastname: Belardinelli
mesh_terms: D000083:Acetanilides / Q000494:pharmacology / Q000627:therapeutic use; D019943:Amino Acid Substitution / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002135:Calcium-Binding Proteins / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003064:Cnidarian Venoms / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D055724:Electrophysiological Phenomena / Q000187:drug effects / Q000502:physiology; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism*; D062554:NAV1.5 Voltage-Gated Sodium Channel; D010455:Peptides / Q000494:pharmacology / Q000627:therapeutic use; D010477:Perfusion; D010766:Phosphorylation / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology / Q000627:therapeutic use; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D034741:RNA, Small Interfering / Q000235:genetics; D011817:Rabbits; D000069458:Ranolazine; D051381:Rats; D017207:Rats, Sprague-Dawley; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism*; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors / Q000378:metabolism; D017180:Tachycardia, Ventricular / Q000139:chemically induced / Q000517:prevention & control; D013779:Tetrodotoxin / Q000494:pharmacology; D014701:Veratridine / Q000494:pharmacology; D000099211:Phospholamban
chemical_list: D000083:Acetanilides; D002118:Calcium; D002135:Calcium-Binding Proteins; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D053148:Caspase 3; D003064:Cnidarian Venoms; D062554:NAV1.5 Voltage-Gated Sodium Channel; D010455:Peptides; D010879:Piperazines; D034741:RNA, Small Interfering; D000069458:Ranolazine; D019837:Ryanodine Receptor Calcium Release Channel; D012964:Sodium; D015222:Sodium Channels; D019831:Sodium-Calcium Exchanger; D013779:Tetrodotoxin; D014701:Veratridine; D000099211:Phospholamban; C568320:SCN5A protein, human; C568321:Scn5a protein, mouse; C568322:Scn5a protein, rat; C514527:autocamptide-2-related inhibitory peptide II; C110374:sodium-calcium exchanger 1; C028800:toxin II (Anemonia sulcata); C505410:Casp3 protein, rat