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Dvir M, Strulovich R, Sachyani D, Ben-Tal Cohen I, Haitin Y, Dessauer C, Pongs O, Kass R, Hirsch JA, Attali B. Long QT mutations at the interface between KCNQ1 helix C and KCNE1 disrupt I(KS) regulation by PKA and PIP₂. J Cell Sci 2014; 127:3943-55. [PMID: 25037568 DOI: 10.1242/jcs.147033] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
KCNQ1 and KCNE1 co-assembly generates the I(KS) K(+) current, which is crucial to the cardiac action potential repolarization. Mutations in their corresponding genes cause long QT syndrome (LQT) and atrial fibrillation. The A-kinase anchor protein, yotiao (also known as AKAP9), brings the I(KS) channel complex together with signaling proteins to achieve regulation upon β1-adrenergic stimulation. Recently, we have shown that KCNQ1 helix C interacts with the KCNE1 distal C-terminus. We postulated that this interface is crucial for I(KS) channel modulation. Here, we examined the yet unknown molecular mechanisms of LQT mutations located at this intracellular intersubunit interface. All LQT mutations disrupted the internal KCNQ1-KCNE1 intersubunit interaction. LQT mutants in KCNQ1 helix C led to a decreased current density and a depolarizing shift of channel activation, mainly arising from impaired phosphatidylinositol-4,5-bisphosphate (PIP2) modulation. In the KCNE1 distal C-terminus, the LQT mutation P127T suppressed yotiao-dependent cAMP-mediated upregulation of the I(KS) current, which was caused by reduced KCNQ1 phosphorylation at S27. Thus, KCNQ1 helix C is important for channel modulation by PIP2, whereas the KCNE1 distal C-terminus appears essential for the regulation of IKS by yotiao-mediated PKA phosphorylation.
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Affiliation(s)
- Meidan Dvir
- Department of Physiology & Pharmacology, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Roi Strulovich
- Department of Biochemistry & Molecular Biology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Dana Sachyani
- Department of Biochemistry & Molecular Biology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Inbal Ben-Tal Cohen
- Department of Physiology & Pharmacology, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Yoni Haitin
- Department of Physiology & Pharmacology, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Carmen Dessauer
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Olaf Pongs
- Institut für Physiologie, Universität des Saarlandes, 66424 Homburg, Germany
| | - Robert Kass
- Department of Pharmacology, Columbia University, New York, NY 10027, USA
| | - Joel A Hirsch
- Department of Biochemistry & Molecular Biology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Bernard Attali
- Department of Physiology & Pharmacology, Tel Aviv University, Tel Aviv, 69978, Israel
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