title: The interaction of caveolin 3 protein with the potassium inward rectifier channel Kir2.1: physiology and pathology related to long qt syndrome 9 (LQT9).
abstract: Mutations in CAV3 cause LQT syndrome 9 (LQT9). A previously reported LQT9 patient had prominent U waves on ECG, a feature that has been correlated with Kir2.1 loss of function. Our objective was to determine whether caveolin 3 (Cav3) associates with Kir2.1 and whether LQT9-associated CAV3 mutations affect the biophysical properties of Kir2.1. Kir2.1 current (IK1) density was measured using the whole-cell voltage clamp technique. WT-Cav3 did not affect IK1. However, F97C-Cav3 and T78M-Cav3 decreased IK1 density significantly by ∼60%, and P104L-Cav3 decreased IK1 density significantly by ∼30% at -60 mV. Immunostained rat heart cryosections and HEK293 cells cotransfected with Kir2.1 and WT-Cav3 both demonstrated colocalization of Kir2.1 and WT-Cav3 by confocal imaging. Cav3 coimmunoprecipitated with Kir2.1 in human ventricular myocytes and in heterologous expression systems. Additionally, FRET efficiency was highly specific, with a molecular distance of 5.6 ± 0.4 nm, indicating close protein location. Colocalization experiments found that Cav3 and Kir2.1 accumulated in the Golgi compartment. On-cell Western blot analysis showed decreased Kir2.1 cell surface expression by 60% when expressed with F97C-Cav3 and by 20% when expressed with P104L-Cav3 compared with WT-Cav3. This is the first report of an association between Cav3 and Kir2.1. The Cav3 mutations F97C-Cav3, P104L-Cav3, and T78M-Cav3 decreased IK1 density significantly. This effect was related to a reduced cell surface expression of Kir2.1. Kir2.1 loss of function is additive to the increase described previously in late INa, prolonging repolarization and leading to arrhythmia generation in Cav3-mediated LQT9.
authors: Department of Medicine, Division of Cardiovascular Medicine and the Cellular and Molecular Arrhythmia Research Program,University of Wisconsin, Madison, Wisconsin 53792, USA.
authors: Ravi
authors: R
authors: Vaidyanathan
authors: Amanda L
authors: AL
authors: Vega
authors: Chunhua
authors: C
authors: Song
authors: Qing
authors: Q
authors: Zhou
authors: Bi-Hua
authors: BH
authors: Tan
authors: Bihua
authors: B
authors: Tan
authors: Stuart
authors: S
authors: Berger
authors: Jonathan C
authors: JC
authors: Makielski
authors: Lee L
authors: LL
authors: Eckhardt
mesh_terms: D000818:Animals; D019556:COS Cells; D051244:Caveolin 3 / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D031541:Fluorescence Resonance Energy Transfer; D006056:Golgi Apparatus / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D008133:Long QT Syndrome / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008564:Membrane Potentials; D008856:Microscopy, Fluorescence; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D032383:Myocytes, Cardiac / Q000502:physiology*; D018408:Patch-Clamp Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport
chemical_list: C417736:CAV3 protein, human; D051244:Caveolin 3; C489457:KCNJ2 protein, human; D024661:Potassium Channels, Inwardly Rectifying
keywords: Arrhythmias, Basic Studies; Cardiomyopathy; Caveolin; Electrophysiology; Ion Channels; Long QT Syndrome (LQTS); Potassium Channels
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