title: ATP stimulates pannexin 1 internalization to endosomal compartments.
abstract: The ubiquitous pannexin 1 (Panx1) ion- and metabolite-permeable channel mediates the release of ATP, a potent signalling molecule. In the present study, we provide striking evidence that ATP, in turn, stimulates internalization of Panx1 to intracellular membranes. These findings hold important implications for understanding the regulation of Panx1 when extracellular ATP is elevated. In the nervous system, this includes phenomena such as synaptic plasticity, pain, precursor cell development and stroke; outside of the nervous system, this includes things like skeletal and smooth muscle activity and inflammation. Within 15 min, ATP led to significant Panx1-EGFP internalization. In a series of experiments, we determined that hydrolysable ATP is the most potent stimulator of Panx1 internalization. We identified two possible mechanisms for Panx1 internalization, including activation of ionotropic purinergic (P2X) receptors and involvement of a putative ATP-sensitive residue in the first extracellular loop of Panx1 (Trp(74)). Internalization was cholesterol-dependent, but clathrin, caveolin and dynamin independent. Detailed analysis of Panx1 at specific endosome sub-compartments confirmed that Panx1 is expressed in endosome membranes of the classical degradation pathway under basal conditions and that elevation of ATP levels diverts a sub-population to recycling endosomes. This is the first report detailing endosome localization of Panx1 under basal conditions and the potential for ATP regulation of its surface expression. Given the ubiquitous expression profile of Panx1 and the importance of ATP signalling, these findings are of critical importance for understanding the role of Panx1 in health and disease.
authors.affiliation: Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria, Canada V8P 5C2.
authors.forename: Andrew K J
authors.initials: AK
authors.lastname: Boyce
authors.affiliation: Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria, Canada V8P 5C2.
authors.forename: Michelle S
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria, Canada V8P 5C2.
authors.forename: Leigh E
authors.initials: LE
authors.lastname: Wicki-Stordeur
authors.affiliation: Division of Medical Sciences and Island Medical Program, University of Victoria, Victoria, Canada V8P 5C2 Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada V6T 1Z3 lswayne@uvic.ca.
authors.forename: Leigh Anne
authors.initials: LA
authors.lastname: Swayne
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D019943:Amino Acid Substitution; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002460:Cell Line; D017630:Connexins / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D058920:Purinergic P2X Receptor Antagonists / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D058486:Receptors, Purinergic P2X7 / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013777:Tetrazoles / Q000494:pharmacology
chemical_list: C523668:3-(5-(2,3-dichlorophenyl)-1H-tetrazol-1-yl)methylpyridine; D017630:Connexins; D009419:Nerve Tissue Proteins; C503631:Panx1 protein, mouse; D058920:Purinergic P2X Receptor Antagonists; D011725:Pyridines; D058486:Receptors, Purinergic P2X7; D011993:Recombinant Fusion Proteins; D013777:Tetrazoles; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D000255:Adenosine Triphosphate
keywords: adenosine 5′-triphosphate (ATP); endocytosis; endosomes; pannexin 1; pannexin1; trafficking