title: Regulation of acid-base transporters by reactive oxygen species following mitochondrial fragmentation.
abstract: Mitochondrial morphology is determined by the balance between the opposing processes of fission and fusion, each of which is regulated by a distinct set of proteins. Abnormalities in mitochondrial dynamics have been associated with a variety of diseases, including neurodegenerative conditions such as Alzheimer's disease, Parkinson's disease, and dominant optic atrophy. Although the genetic determinants of fission and fusion are well recognized, less is known about the mechanism(s) whereby altered morphology contributes to the underlying pathophysiology of these disease states. Previous work from our laboratory identified a role for mitochondrial dynamics in intracellular pH homeostasis in both mammalian cell culture and in the genetic model organism Caenorhabditis elegans. Here we show that the acidification seen in mutant animals that have lost the ability to fuse their mitochondrial inner membrane occurs through a reactive oxygen species (ROS)-dependent mechanism and can be suppressed through the use of pharmacological antioxidants targeted specifically at the mitochondrial matrix. Physiological approaches examining the activity of endogenous mammalian acid-base transport proteins in rat liver Clone 9 cells support the idea that ROS signaling to sodium-proton exchangers contributes to acidification. Because maintaining pH homeostasis is essential for cell function and viability, the results of this work provide new insight into the pathophysiology associated with the loss of inner mitochondrial membrane fusion.
authors.affiliation: Department of Biomedical Genetics, University of Rochester Medical Center, NY 14642, USA.
authors.forename: David
authors.initials: D
authors.lastname: Johnson
authors.forename: Erik
authors.initials: E
authors.lastname: Allman
authors.forename: Keith
authors.initials: K
authors.lastname: Nehrke
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D016466:CHO Cells; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D006224:Cricetinae; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D029742:Caenorhabditis elegans Proteins; D026901:Membrane Transport Proteins; D017382:Reactive Oxygen Species; D017923:Sodium-Hydrogen Exchangers; C543815:EAT-3 protein, C elegans; D020558:GTP Phosphohydrolases