Shuai Guo, Andy Hudmon, Firoj K Sahoo, Madeline R Motes, Wen-Chin Tsai, Peng-Sheng Chen, Michael Rubart
{"title":"p. n98s -钙调蛋白突变小鼠心室心肌细胞的K+电流。","authors":"Shuai Guo, Andy Hudmon, Firoj K Sahoo, Madeline R Motes, Wen-Chin Tsai, Peng-Sheng Chen, Michael Rubart","doi":"10.1152/ajpheart.00470.2024","DOIUrl":null,"url":null,"abstract":"<p><p>Missense mutations in calmodulin (CaM)-encoding genes are associated with life-threatening ventricular arrhythmia syndromes. Here, we investigated the role of cardiac K<sup>+</sup> channel dysregulation in arrhythmogenic long QT syndrome (LQTS) using a knock-in mouse model heterozygous for a recurrent mutation (p.N98S) in the <i>Calm1</i> gene (<i>Calm1</i><sup>N98S/+</sup>). Single-cell patch-clamp technique and whole heart optical voltage mapping were used to assess action potentials and whole cell currents. Ventricular action potential duration (APD) at baseline was similar between genotypes. The β-adrenergic agonist isoproterenol prolonged APD in myocytes and isolated perfused hearts from <i>Calm1</i><sup>N98S/+</sup>, but not wild-type (<i>Calm1</i><sup>+/+</sup>), mice. Current density-voltage relationships for the small-conductance calcium-activated K<sup>+</sup> (SK) current and the inward rectifier K<sup>+</sup> current did not significantly differ between <i>Calm1</i><sup>+/+</sup> and <i>Calm1</i><sup>N98S/+</sup> ventricular cardiomyocytes ± isoproterenol. Peak densities of other voltage-gated K<sup>+</sup> currents were significantly larger in <i>Calm1</i><sup>N98S/+</sup> versus <i>Calm1</i><sup>+/+</sup> cells at voltages ≥40 mV, both without and with isoproterenol. Isoproterenol reduced outward K<sub>ATP</sub> currents more in <i>Calm1</i><sup>N98S/+</sup> versus <i>Calm1</i><sup>+/+</sup> myocytes. Dialysis of <i>Calm1</i><sup>+/+</sup> cardiomyocytes with exogenous wild-type or N98S-CaM protein (5 µmol/L) via the pipette, respectively, increased and eliminated SK currents. The specific SK channel inhibitor apamin did not significantly alter the APD of <i>Calm1</i><sup>+/+</sup> or <i>Calm1</i><sup>N98S/+</sup> hearts ± isoproterenol. Thus, dysregulation of SK or voltage-gated K<sup>+</sup> channels does not contribute to the β-adrenergic-induced LQTS of <i>Calm1</i><sup>N98S/+</sup> mice, possibly because cardiomyocyte content of endogenous N98S-CaM and/or its affinity for CaM-binding domains may be too low to modulate channel properties. The larger K<sub>ATP</sub> current inhibition by isoproterenol may delay <i>Calm1</i><sup>N98S/+</sup> myocyte repolarization at low intracellular [ATP].<b>NEW & NOTEWORTHY</b> Despite in vitro and in silico evidence implicating cardiac K<sup>+</sup> channel dysregulation in LQTS associated with missense mutations in genes-encoding calmodulin, their effects on native cardiac K<sup>+</sup> currents are unknown. Using a knock-in mouse model harboring the p.N98S mutation in the <i>Calm1</i> gene, we found no evidence for dysregulation of major cardiac K<sup>+</sup> channels. Although these data do not support mechanistic findings from heterologous systems, our finding impacts efforts to improve therapies for calmodulinopathies.</p>","PeriodicalId":7692,"journal":{"name":"American journal of physiology. Heart and circulatory physiology","volume":" ","pages":"H658-H675"},"PeriodicalIF":4.1000,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"K<sup>+</sup> currents in ventricular cardiomyocytes of p.N98S-calmodulin mutant mice.\",\"authors\":\"Shuai Guo, Andy Hudmon, Firoj K Sahoo, Madeline R Motes, Wen-Chin Tsai, Peng-Sheng Chen, Michael Rubart\",\"doi\":\"10.1152/ajpheart.00470.2024\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>Missense mutations in calmodulin (CaM)-encoding genes are associated with life-threatening ventricular arrhythmia syndromes. Here, we investigated the role of cardiac K<sup>+</sup> channel dysregulation in arrhythmogenic long QT syndrome (LQTS) using a knock-in mouse model heterozygous for a recurrent mutation (p.N98S) in the <i>Calm1</i> gene (<i>Calm1</i><sup>N98S/+</sup>). Single-cell patch-clamp technique and whole heart optical voltage mapping were used to assess action potentials and whole cell currents. Ventricular action potential duration (APD) at baseline was similar between genotypes. The β-adrenergic agonist isoproterenol prolonged APD in myocytes and isolated perfused hearts from <i>Calm1</i><sup>N98S/+</sup>, but not wild-type (<i>Calm1</i><sup>+/+</sup>), mice. Current density-voltage relationships for the small-conductance calcium-activated K<sup>+</sup> (SK) current and the inward rectifier K<sup>+</sup> current did not significantly differ between <i>Calm1</i><sup>+/+</sup> and <i>Calm1</i><sup>N98S/+</sup> ventricular cardiomyocytes ± isoproterenol. Peak densities of other voltage-gated K<sup>+</sup> currents were significantly larger in <i>Calm1</i><sup>N98S/+</sup> versus <i>Calm1</i><sup>+/+</sup> cells at voltages ≥40 mV, both without and with isoproterenol. Isoproterenol reduced outward K<sub>ATP</sub> currents more in <i>Calm1</i><sup>N98S/+</sup> versus <i>Calm1</i><sup>+/+</sup> myocytes. Dialysis of <i>Calm1</i><sup>+/+</sup> cardiomyocytes with exogenous wild-type or N98S-CaM protein (5 µmol/L) via the pipette, respectively, increased and eliminated SK currents. The specific SK channel inhibitor apamin did not significantly alter the APD of <i>Calm1</i><sup>+/+</sup> or <i>Calm1</i><sup>N98S/+</sup> hearts ± isoproterenol. Thus, dysregulation of SK or voltage-gated K<sup>+</sup> channels does not contribute to the β-adrenergic-induced LQTS of <i>Calm1</i><sup>N98S/+</sup> mice, possibly because cardiomyocyte content of endogenous N98S-CaM and/or its affinity for CaM-binding domains may be too low to modulate channel properties. The larger K<sub>ATP</sub> current inhibition by isoproterenol may delay <i>Calm1</i><sup>N98S/+</sup> myocyte repolarization at low intracellular [ATP].<b>NEW & NOTEWORTHY</b> Despite in vitro and in silico evidence implicating cardiac K<sup>+</sup> channel dysregulation in LQTS associated with missense mutations in genes-encoding calmodulin, their effects on native cardiac K<sup>+</sup> currents are unknown. Using a knock-in mouse model harboring the p.N98S mutation in the <i>Calm1</i> gene, we found no evidence for dysregulation of major cardiac K<sup>+</sup> channels. Although these data do not support mechanistic findings from heterologous systems, our finding impacts efforts to improve therapies for calmodulinopathies.</p>\",\"PeriodicalId\":7692,\"journal\":{\"name\":\"American journal of physiology. Heart and circulatory physiology\",\"volume\":\" \",\"pages\":\"H658-H675\"},\"PeriodicalIF\":4.1000,\"publicationDate\":\"2025-03-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"American journal of physiology. Heart and circulatory physiology\",\"FirstCategoryId\":\"3\",\"ListUrlMain\":\"https://doi.org/10.1152/ajpheart.00470.2024\",\"RegionNum\":2,\"RegionCategory\":\"医学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"2024/12/31 0:00:00\",\"PubModel\":\"Epub\",\"JCR\":\"Q1\",\"JCRName\":\"CARDIAC & CARDIOVASCULAR SYSTEMS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"American journal of physiology. Heart and circulatory physiology","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1152/ajpheart.00470.2024","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/12/31 0:00:00","PubModel":"Epub","JCR":"Q1","JCRName":"CARDIAC & CARDIOVASCULAR SYSTEMS","Score":null,"Total":0}
K+ currents in ventricular cardiomyocytes of p.N98S-calmodulin mutant mice.
Missense mutations in calmodulin (CaM)-encoding genes are associated with life-threatening ventricular arrhythmia syndromes. Here, we investigated the role of cardiac K+ channel dysregulation in arrhythmogenic long QT syndrome (LQTS) using a knock-in mouse model heterozygous for a recurrent mutation (p.N98S) in the Calm1 gene (Calm1N98S/+). Single-cell patch-clamp technique and whole heart optical voltage mapping were used to assess action potentials and whole cell currents. Ventricular action potential duration (APD) at baseline was similar between genotypes. The β-adrenergic agonist isoproterenol prolonged APD in myocytes and isolated perfused hearts from Calm1N98S/+, but not wild-type (Calm1+/+), mice. Current density-voltage relationships for the small-conductance calcium-activated K+ (SK) current and the inward rectifier K+ current did not significantly differ between Calm1+/+ and Calm1N98S/+ ventricular cardiomyocytes ± isoproterenol. Peak densities of other voltage-gated K+ currents were significantly larger in Calm1N98S/+ versus Calm1+/+ cells at voltages ≥40 mV, both without and with isoproterenol. Isoproterenol reduced outward KATP currents more in Calm1N98S/+ versus Calm1+/+ myocytes. Dialysis of Calm1+/+ cardiomyocytes with exogenous wild-type or N98S-CaM protein (5 µmol/L) via the pipette, respectively, increased and eliminated SK currents. The specific SK channel inhibitor apamin did not significantly alter the APD of Calm1+/+ or Calm1N98S/+ hearts ± isoproterenol. Thus, dysregulation of SK or voltage-gated K+ channels does not contribute to the β-adrenergic-induced LQTS of Calm1N98S/+ mice, possibly because cardiomyocyte content of endogenous N98S-CaM and/or its affinity for CaM-binding domains may be too low to modulate channel properties. The larger KATP current inhibition by isoproterenol may delay Calm1N98S/+ myocyte repolarization at low intracellular [ATP].NEW & NOTEWORTHY Despite in vitro and in silico evidence implicating cardiac K+ channel dysregulation in LQTS associated with missense mutations in genes-encoding calmodulin, their effects on native cardiac K+ currents are unknown. Using a knock-in mouse model harboring the p.N98S mutation in the Calm1 gene, we found no evidence for dysregulation of major cardiac K+ channels. Although these data do not support mechanistic findings from heterologous systems, our finding impacts efforts to improve therapies for calmodulinopathies.
期刊介绍:
The American Journal of Physiology-Heart and Circulatory Physiology publishes original investigations, reviews and perspectives on the physiology of the heart, vasculature, and lymphatics. These articles include experimental and theoretical studies of cardiovascular function at all levels of organization ranging from the intact and integrative animal and organ function to the cellular, subcellular, and molecular levels. The journal embraces new descriptions of these functions and their control systems, as well as their basis in biochemistry, biophysics, genetics, and cell biology. Preference is given to research that provides significant new mechanistic physiological insights that determine the performance of the normal and abnormal heart and circulation.