title: Unique hexosaminidase reduces metabolic survival signal and sensitizes cardiac myocytes to hypoxia/reoxygenation injury.
abstract: Metabolic signaling through the posttranslational linkage of N-acetylglucosamine (O-GlcNAc) to cellular proteins represents a unique signaling paradigm operative during lethal cellular stress and a pathway that we and others have recently shown to exert cytoprotective effects in vitro and in vivo. Accordingly, the present work addresses the contribution of the hexosaminidase responsible for removing O-GlcNAc (ie, O-GlcNAcase) from proteins. We used pharmacological inhibition, viral overexpression, and RNA interference of O-GlcNAcase in isolated cardiac myocytes to establish its role during acute hypoxia/reoxygenation. Elevated O-GlcNAcase expression significantly reduced O-GlcNAc levels and augmented posthypoxic cell death. Conversely, short interfering RNA directed against, or pharmacological inhibition of, O-GlcNAcase significantly augmented O-GlcNAc levels and reduced posthypoxic cell death. On the mechanistic front, we evaluated posthypoxic mitochondrial membrane potential and found that repression of O-GlcNAcase activity improves, whereas augmentation impairs, mitochondrial membrane potential recovery. Similar beneficial effects on posthypoxic calcium overload were also evident. Such changes were evident without significant alteration in expression of the major putative components of the mitochondrial permeability transition pore (ie, voltage-dependent anion channel, adenine nucleotide translocase, cyclophilin D). The present results provide definitive evidence that O-GlcNAcase antagonizes posthypoxic cardiac myocyte survival. Moreover, such results support a renewed approach to the contribution of metabolism and metabolic signaling to the determination of cell fate.
authors.affiliation: Institute of Molecular Cardiology, Department of Medicine, University of Louisville, KY, USA.
authors.forename: Gladys A
authors.initials: GA
authors.lastname: Ngoh
authors.forename: Heberty T
authors.initials: HT
authors.lastname: Facundo
authors.forename: Tariq
authors.initials: T
authors.lastname: Hamid
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Dillmann
authors.forename: Natasha E
authors.initials: NE
authors.lastname: Zachara
authors.forename: Steven P
authors.initials: SP
authors.lastname: Jones
mesh_terms: D000117:Acetylglucosamine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D002316:Cardiotonic Agents / Q000494:pharmacology*; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured / Q000187:drug effects / Q000201:enzymology; D006031:Glycosylation / Q000187:drug effects; D019157:Ischemic Preconditioning, Myocardial; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D033681:Mitochondrial Membrane Transport Proteins / Q000502:physiology; D000083162:Mitochondrial Permeability Transition Pore; D017202:Myocardial Ischemia / Q000188:drug therapy / Q000201:enzymology; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology; D010091:Oximes / Q000494:pharmacology*; D048448:Phenylcarbamates / Q000494:pharmacology*; D014176:Protein Biosynthesis / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D001619:beta-N-Acetylhexosaminidases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*
chemical_list: D002316:Cardiotonic Agents; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D010091:Oximes; D048448:Phenylcarbamates; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; C068836:N-acetylglucosaminono-1,5-lactone O-(phenylcarbamoyl)oxime; C110628:hexosaminidase C; D001619:beta-N-Acetylhexosaminidases; D002118:Calcium; D000117:Acetylglucosamine