title: Transient contraction of mitochondria induces depolarization through the inner membrane dynamin OPA1 protein.
abstract: Dynamin-related membrane remodeling proteins regulate mitochondrial morphology by mediating fission and fusion. Although mitochondrial morphology is considered an important factor in maintaining mitochondrial function, a direct mechanistic link between mitochondrial morphology and function has not been defined. We report here a previously unrecognized cellular process of transient contraction of the mitochondrial matrix. Importantly, we found that this transient morphological contraction of mitochondria is accompanied by a reversible loss or decrease of inner membrane potential. Fission deficiency greatly amplified this phenomenon, which functionally exhibited an increase of inner membrane proton leak. We found that electron transport activity is necessary for the morphological contraction of mitochondria. Furthermore, we discovered that silencing the inner membrane-associated dynamin optic atrophy 1 (OPA1) in fission deficiency prevented mitochondrial depolarization and decreased proton leak without blocking mitochondrial contraction, indicating that OPA1 is a factor in coupling matrix contraction to mitochondrial depolarization. Our findings show that transient matrix contraction is a novel cellular mechanism regulating mitochondrial activity through the function of the inner membrane dynamin OPA1.
authors.affiliation: Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia 30912.
authors.forename: Hakjoo
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia 30912. Electronic address: yyoon@gru.edu.
authors.forename: Yisang
authors.initials: Y
authors.lastname: Yoon
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004579:Electron Transport; D020558:GTP Phosphohydrolases; D007425:Intracellular Membranes / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial; D051379:Mice; D018345:Mice, Knockout; D008928:Mitochondria / Q000502:physiology*
chemical_list: D020558:GTP Phosphohydrolases; C498809:Opa1 protein, mouse
keywords: Bioenergetics; Drp1; Dynamin; Electron Transfer; Membrane; Membrane Fusion; Mitochondria; Mitochondrial Fission; OPA1; Proton Leak