title: Engineered Cx40 variants increased docking and function of heterotypic Cx40/Cx43 gap junction channels.
abstract: Gap junction (GJ) channels provide low resistance passages for rapid action potential propagation in the heart. Both connexin40 (Cx40) and Cx43 are abundantly expressed in and frequently co-localized between atrial myocytes, possibly forming heterotypic GJ channels. However, conflicting results have been obtained on the functional status of heterotypic Cx40/Cx43 GJs. Here we provide experimental evidence that the docking and formation of heterotypic Cx40/Cx43 GJs can be substantially increased by designed Cx40 variants on the extracellular domains (E1 and E2). Specifically, Cx40 D55N and P193Q, substantially increased the probability to form GJ plaque-like structures at the cell-cell interfaces with Cx43 in model cells. More importantly the coupling conductance (Gj) of D55N/Cx43 and P193Q/Cx43 GJ channels are significantly increased from the Gj of Cx40/Cx43 in N2A cells. Our homology models indicate the electrostatic interactions and surface structures at the docking interface are key factors preventing Cx40 from docking to Cx43. Improving heterotypic Gj of these atrial connexins might be potentially useful in improving the coupling and synchronization of atrial myocardium.
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Arjewan
authors.initials: A
authors.lastname: Jassim
authors.affiliation: Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Aoyama
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Willy G
authors.initials: WG
authors.lastname: Ye
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Honghong
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada. Electronic address: donglin.bai@schulich.uwo.ca.
authors.forename: Donglin
authors.initials: D
authors.lastname: Bai
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D018031:Connexin 43 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017630:Connexins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism* / Q000648:ultrastructure; D015870:Gene Expression; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D062105:Molecular Docking Simulation; D008969:Molecular Sequence Data; D009154:Mutation; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D015202:Protein Engineering; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D000097003:Gap Junction alpha-5 Protein
chemical_list: D018031:Connexin 43; D017630:Connexins; D049452:Green Fluorescent Proteins; D011993:Recombinant Fusion Proteins; D000097003:Gap Junction alpha-5 Protein
keywords: Connexin40; Connexin43; Docking mechanism; Gap junction channel; Heterotypic docking