title: Diverse post-translational modifications of the pannexin family of channel-forming proteins.
abstract: The pannexin family of channel-forming proteins is composed of 3 distinct but related members called Panx1, Panx2, and Panx3. Pannexins have been implicated in many physiological processes as well as pathological conditions, primarily through their function as ATP release channels. However, it is currently unclear if all pannexins are subject to similar or different post-translational modifications as most studies have focused primarily on Panx1. Using in vitro biochemical assays performed on ectopically expressed pannexins in HEK-293T cells, we confirmed that all 3 pannexins are N-glycosylated to different degrees, but they are not modified by sialylation or O-linked glycosylation in a manner that changes their apparent molecular weight. Using cell-free caspase assays, we also discovered that similar to Panx1, the C-terminus of Panx2 is a substrate for caspase cleavage. Panx3, on the other hand, is not subject to caspase digestion but an in vitro biotin switch assay revealed that it was S-nitrosylated by nitric oxide donors. Taken together, our findings uncover novel and diverse pannexin post-translational modifications suggesting that they may be differentially regulated for distinct or overlapping cellular and physiological functions.
authors.affiliation: Department of Anatomy and Cell Biology; University of Western Ontario; London, ON Canada.
authors.forename: Silvia
authors.initials: S
authors.lastname: Penuela
authors.affiliation: Robert M Berne Cardiovascular Research Center; Department of Molecular Physiology and Biological Physics; University of Virginia; Charlottesville, VA USA.
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Lohman
authors.affiliation: Department of Anatomy and Cell Biology; University of Western Ontario; London, ON Canada; Department of Molecular Genetics; University of Toronto; The Hospital for Sick Children; Toronto, ON Canada.
authors.forename: Wesley
authors.initials: W
authors.lastname: Lai
authors.affiliation: Department of Biochemistry; University of Western Ontario; London, ON Canada.
authors.forename: Laszlo
authors.initials: L
authors.lastname: Gyenis
authors.affiliation: Department of Biochemistry; University of Western Ontario; London, ON Canada.
authors.forename: David W
authors.initials: DW
authors.lastname: Litchfield
authors.affiliation: Robert M Berne Cardiovascular Research Center; Department of Molecular Physiology and Biological Physics; University of Virginia; Charlottesville, VA USA.
authors.forename: Brant E
authors.initials: BE
authors.lastname: Isakson
authors.affiliation: Department of Anatomy and Cell Biology; University of Western Ontario; London, ON Canada.
authors.forename: Dale W
authors.initials: DW
authors.lastname: Laird
mesh_terms: D020169:Caspases / Q000378:metabolism; D017630:Connexins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006031:Glycosylation; D057809:HEK293 Cells; D006801:Humans; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational
chemical_list: D017630:Connexins; D009419:Nerve Tissue Proteins; C492764:PANX1 protein, human; C492765:PANX2 protein, human; C492766:PANX3 protein, human; D020169:Caspases
keywords: Pannexin; Panx1; Panx2; Panx3; caspase; glycosylation; nitrosylation; post-translational modifications