31 Twig, G. Elorza, A. Molina, A. J. Mohamed, H. Wikstrom, J. D. Walzer, G. Stiles, L. Haigh, S. E. Katz, S. Las, G. Alroy, J. Wu, M. Py, B. F. Yuan, J. Deeney, J. T. Corkey, B. E. Shirihai, O. S. 2008 Embo J 27 2 433-46 Jan 23 1460-2075 (Electronic) 18200046 Mutation Models, Biological Mitochondrial Proteins/genetics/metabolism/*physiology Mitochondria/metabolism/*physiology Microtubule-Associated Proteins/genetics/physiology Microscopy, Confocal Mice, Inbred C57BL Mice Membrane Potential, Mitochondrial/physiology Male Insulin-Secreting Cells/cytology/metabolism Insulin/secretion Green Fluorescent Proteins/genetics/metabolism Genotype GTP Phosphohydrolases/genetics/metabolism Cell Line Autophagy/genetics/*physiology Animals Reactive Oxygen Species/metabolism Models Biological Microscopy Confocal Inbred C57BL Membrane Potential Mitochondrial/physiology Accumulation of depolarized mitochondria within beta-cells has been associated with oxidative damage and development of diabetes. To determine the source and fate of depolarized mitochondria, individual mitochondria were photolabeled and tracked through fusion and fission. Mitochondria were found to go through frequent cycles of fusion and fission in a 'kiss and run' pattern. Fission events often generated uneven daughter units: one daughter exhibited increased membrane potential (delta psi(m)) and a high probability of subsequent fusion, while the other had decreased membrane potential and a reduced probability for a fusion event. Together, this pattern generated a subpopulation of non-fusing mitochondria that were found to have reduced delta psi(m) and decreased levels of the fusion protein OPA1. Inhibition of the fission machinery through DRP1(K38A) or FIS1 RNAi decreased mitochondrial autophagy and resulted in the accumulation of oxidized mitochondrial proteins, reduced respiration and impaired insulin secretion. Pulse chase and arrest of autophagy at the pre-proteolysis stage reveal that before autophagy mitochondria lose delta psi(m) and OPA1, and that overexpression of OPA1 decreases mitochondrial autophagy. Together, these findings suggest that fission followed by selective fusion segregates dysfunctional mitochondria and permits their removal by autophagy. 5R01HL071629-03/HL/NHLBI NIH HHS/United StatesP41 RR001395/RR/NCRR NIH HHS/United StatesR01 DK074778/DK/NIDDK NIH HHS/United StatesJournal ArticleResearch Support, N.I.H., ExtramuralResearch Support, U.S. Gov't, Non-P.H.S.England http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=18200046