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D242N, a KV7.1 LQTS mutation uncovers a key residue for IKs voltage dependence

AuthorsMoreno, Cristina; Oliveras, Anna; Bartolucci, Chiara; Muñoz, Carmen; Cruz, Alicia de la CSIC; Peraza, Diego A.; Gimeno, Juan R.; Martín-Martínez, Mercedes CSIC ORCID; Severi, Stefano; Felipe, Antonio; Lambiase, Pier; González, Teresa; Valenzuela, Carmen CSIC ORCID CVN
Issue Date2017
CitationVI RECI Meeting (2017)
AbstractKV7.1 and KCNE1 co-assemble to give rise to the IKs current, one of the most important repolarizing currents of the cardiac action potential. Its relevance is underscored by the identification of more than 500 mutations in KV7.1 and, at least, 36 in KCNE1, that cause Long QT Syndrome (LQTS). The aim of this study was to characterize the biophysical and cellular consequences of the D242N KV7.1 mutation associated with the LQTS. The mutation is located in the S4 transmembrane segment, within the voltage sensor of the KV7.1 channel, disrupting the conserved charge balance of this region. Perforated patch-clamp experiments show that, unexpectedly, the mutation did not disrupt the voltagedependent activation but it removed the inactivation and slowed the activation kinetics of D242N KV7.1 channels. Biotinylation of cell-surface protein and co-immunoprecipitation experiments revealed that neither plasma membrane targeting nor co-assembly between KV7.1 and KCNE1 was altered by the mutation. However, the association of D242N KV7.1 with KCNE1 strongly shifted the voltage dependence of activation to more depolarized potentials (+50mV), hindering IKs current at physiologically relevant membrane potentials. Both functional and computational analysis suggest that the clinical phenotype of the LQTS patients carrying the D242N mutation is due to impaired action potential adaptation to exercise and, in particular, to increase in heart rate. Moreover, our data identify D242 aminoacidic position as a potential residue involved in the KCNE1-mediated regulation of the voltage dependence of activation of the KV7.1 channel.
DescriptionResumen del trabajo presentado al VI Meeting de la Red Española de Canales Ióniocs (RECI), celebrado en Santiago de Compostela del 6 al 8 de septiembre de 2017.
Appears in Collections:(IIBM) Comunicaciones congresos

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