title: A direct interaction between the sigma-1 receptor and the hERG voltage-gated K+ channel revealed by atomic force microscopy and homogeneous time-resolved fluorescence (HTRF®).
abstract: The sigma-1 receptor is an endoplasmic reticulum chaperone protein, widely expressed in central and peripheral tissues, which can translocate to the plasma membrane and modulate the function of various ion channels. The human ether-à-go-go-related gene encodes hERG, a cardiac voltage-gated K(+) channel that is abnormally expressed in many human cancers and is known to interact functionally with the sigma-1 receptor. Our aim was to investigate the nature of the interaction between the sigma-1 receptor and hERG. We show that the two proteins can be co-isolated from a detergent extract of stably transfected HEK-293 cells, consistent with a direct interaction between them. Atomic force microscopy imaging of the isolated protein confirmed the direct binding of the sigma-1 receptor to hERG monomers, dimers, and tetramers. hERG dimers and tetramers became both singly and doubly decorated by sigma-1 receptors; however, hERG monomers were only singly decorated. The distribution of angles between pairs of sigma-1 receptors bound to hERG tetramers had two peaks, at ∼90 and ∼180° in a ratio of ∼2:1, indicating that the sigma-1 receptor interacts with hERG with 4-fold symmetry. Homogeneous time-resolved fluorescence (HTRF®) allowed the detection of the interaction between the sigma-1 receptor and hERG within the plane of the plasma membrane. This interaction was resistant to sigma ligands, but was decreased in response to cholesterol depletion of the membrane. We suggest that the sigma-1 receptor may bind to hERG in the endoplasmic reticulum, aiding its assembly and trafficking to the plasma membrane.
authors.affiliation: Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, United Kingdom.
authors.forename: Dilshan
authors.initials: D
authors.lastname: Balasuriya
authors.affiliation: Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, United Kingdom.
authors.forename: Lauren
authors.initials: L
authors.lastname: D'Sa
authors.affiliation: Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, United Kingdom.
authors.forename: Ronel
authors.initials: R
authors.lastname: Talker
authors.affiliation: CisBio Bioassays, Parc Marcel Boiteux BP 84175, 30200 Codolet, France, and.
authors.forename: Elodie
authors.initials: E
authors.lastname: Dupuis
authors.affiliation: CisBio Bioassays, Parc Marcel Boiteux BP 84175, 30200 Codolet, France, and.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Maurin
authors.affiliation: Institut de Biologie de Valrose (iBV), CNRS UMR 7277, INSERM U1091 UNS, Faculté des Sciences, Université de Nice Sophia Antipolis, 06108 Nice Cedex 2, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Martin
authors.affiliation: Institut de Biologie de Valrose (iBV), CNRS UMR 7277, INSERM U1091 UNS, Faculté des Sciences, Université de Nice Sophia Antipolis, 06108 Nice Cedex 2, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Borgese
authors.affiliation: Institut de Biologie de Valrose (iBV), CNRS UMR 7277, INSERM U1091 UNS, Faculté des Sciences, Université de Nice Sophia Antipolis, 06108 Nice Cedex 2, France. Electronic address: olivier.soriani@unice.fr.
authors.forename: Olivier
authors.initials: O
authors.lastname: Soriani
authors.affiliation: Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, United Kingdom,. Electronic address: jme1000@cam.ac.uk.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Edwardson
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D002784:Cholesterol / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D000072237:ERG1 Potassium Channel; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000939:Epitopes / Q000378:metabolism; D051638:Ether-A-Go-Go Potassium Channels / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007477:Ions; D008024:Ligands; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D017480:Receptors, sigma / Q000378:metabolism*; D014162:Transfection; D000097605:Sigma-1 Receptor
chemical_list: D002784:Cholesterol; D018076:DNA, Complementary; D000072237:ERG1 Potassium Channel; D000939:Epitopes; D051638:Ether-A-Go-Go Potassium Channels; D007477:Ions; D008024:Ligands; D017480:Receptors, sigma; D000097605:Sigma-1 Receptor; C000606913:KCNH2 protein, human
keywords: Atomic Force Microscopy (AFM); Fluorescence Resonance Energy Transfer (FRET); Molecular Imaging; Protein Complex; Sigma Receptor; hERG