title: A quantized mechanism for activation of pannexin channels.
abstract: Pannexin 1 (PANX1) subunits form oligomeric plasma membrane channels that mediate nucleotide release for purinergic signalling, which is involved in diverse physiological processes such as apoptosis, inflammation, blood pressure regulation, and cancer progression and metastasis. Here we explore the mechanistic basis for PANX1 activation by using wild type and engineered concatemeric channels. We find that PANX1 activation involves sequential stepwise sojourns through multiple discrete open states, each with unique channel gating and conductance properties that reflect contributions of the individual subunits of the hexamer. Progressive PANX1 channel opening is directly linked to permeation of ions and large molecules (ATP and fluorescent dyes) and occurs during both irreversible (caspase cleavage-mediated) and reversible (α1 adrenoceptor-mediated) forms of channel activation. This unique, quantized activation process enables fine tuning of PANX1 channel activity and may be a generalized regulatory mechanism for other related multimeric channels.
authors.affiliation: Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
authors.forename: Yu-Hsin
authors.initials: YH
authors.lastname: Chiu
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
authors.forename: Xueyao
authors.initials: X
authors.lastname: Jin
authors.affiliation: Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.|Center for Cell Clearance, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Medina
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Leonhardt
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.|Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
authors.forename: Volker
authors.initials: V
authors.lastname: Kiessling
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
authors.forename: Brad C
authors.initials: BC
authors.lastname: Bennett
authors.affiliation: Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
authors.forename: Shaofang
authors.initials: S
authors.lastname: Shu
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.|Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
authors.forename: Lukas K
authors.initials: LK
authors.lastname: Tamm
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.|Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Yeager
authors.affiliation: Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.|Center for Cell Clearance, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
authors.forename: Kodi S
authors.initials: KS
authors.lastname: Ravichandran
authors.affiliation: Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.|Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Bayliss
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D002229:Carbenoxolone / Q000494:pharmacology; D061945:Caspase Inhibitors / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology*; D017630:Connexins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000648:ultrastructure; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D024841:Fluoroquinolones / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D007477:Ions / Q000378:metabolism; D019169:Jurkat Cells; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008854:Microscopy, Electron; D009287:Naphthyridines / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000648:ultrastructure; D018408:Patch-Clamp Techniques; D055503:Protein Multimerization / Q000502:physiology*; D011804:Quinolines / Q000494:pharmacology; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D017630:Connexins; D005456:Fluorescent Dyes; D024841:Fluoroquinolones; D007477:Ions; D009287:Naphthyridines; D009419:Nerve Tissue Proteins; C492764:PANX1 protein, human; D011804:Quinolines; D018340:Receptors, Adrenergic, alpha-1; C468548:quinoline-val-asp(OMe)-CH2-OPH; D000255:Adenosine Triphosphate; C080163:trovafloxacin; D020169:Caspases; D002229:Carbenoxolone