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Impact of KCNE subunits on KCNQ1 (Kv7.1) channel membrane surface targeting

Authors

  • Meritxell Roura-Ferrer,

    1. Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
    2. Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, Leioa, Spain
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  • Laura Solé,

    1. Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
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  • Anna Oliveras,

    1. Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
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  • Rinat Dahan,

    1. Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
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  • Joanna Bielanska,

    1. Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
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  • Álvaro Villarroel,

    1. Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, Leioa, Spain
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  • Núria Comes,

    1. Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
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  • Antonio Felipe

    Corresponding author
    1. Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
    • Molecular Physiology Laboratory, Departament de Bioquímica i Biología Molecular, Universitat de Barcelona, Avda Diagonal 645, E-08028 Barcelona, Spain.
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Abstract

The KCNQ1 (Kv7.1) channel plays an important role in cardiovascular physiology. Cardiomyocytes co-express KCNQ1 with KCNE1-5 proteins. KCNQ1 may co-associate with multiple KCNE regulatory subunits to generate different biophysically and pharmacologically distinct channels. Increasing evidence indicates that the location and targeting of channels are important determinants of their function. In this context, the presence of K+ channels in sphingolipid–cholesterol-enriched membrane microdomains (lipid rafts) is under investigation. Lipid rafts are important for cardiovascular functioning. We aimed to determine whether KCNE subunits modify the localization and targeting of KCNQ1 channels in lipid rafts microdomains. HEK-293 cells were transiently transfected with KCNQ1 and KCNE1–5, and their traffic and presence in lipid rafts were analyzed. Only KCNQ1 and KCNE3, when expressed alone, co-localized in raft fractions. In addition, while KCNE2 and KCNE5 notably stained the cell surface, KCNQ1 and the rest of the KCNEs showed strong intracellular retention. KCNQ1 targets multiple membrane surface microdomains upon association with KCNE peptides. Thus, while KCNQ1/KCNE1 and KCNQ1/KCNE2 channels target lipid rafts, KCNQ1 associated with KCNE3–5 did not. Channel membrane dynamics, analyzed by fluorescence recovery after photobleaching (FRAP) experiments, further supported these results. In conclusion, the trafficking and targeting pattern of KCNQ1 can be influenced by its association with KCNEs. Since KCNQ1 is crucial for cardiovascular physiology, the temporal and spatial regulations that different KCNE subunits may confer to the channels could have a dramatic impact on membrane electrical activity and putative endocrine regulation. J. Cell. Physiol. 225: 692–700, 2010. © 2010 Wiley-Liss, Inc.

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