title: Bax/Bak promote sumoylation of DRP1 and its stable association with mitochondria during apoptotic cell death.
abstract: Dynamin-related protein 1 (DRP1) plays an important role in mitochondrial fission at steady state and during apoptosis. Using fluorescence recovery after photobleaching, we demonstrate that in healthy cells, yellow fluorescent protein (YFP)-DRP1 recycles between the cytoplasm and mitochondria with a half-time of 50 s. Strikingly, during apoptotic cell death, YFP-DRP1 undergoes a transition from rapid recycling to stable membrane association. The rapid cycling phase that characterizes the early stages of apoptosis is independent of Bax/Bak. However, after Bax recruitment to the mitochondrial membranes but before the loss of mitochondrial membrane potential, YFP-DRP1 becomes locked on the membrane, resulting in undetectable fluorescence recovery. This second phase in DRP1 cycling is dependent on the presence of Bax/Bak but independent of hFis1 and mitochondrial fragmentation. Coincident with Bax activation, we detect a Bax/Bak-dependent stimulation of small ubiquitin-like modifier-1 conjugation to DRP1, a modification that correlates with the stable association of DRP1 with mitochondrial membranes. Altogether, these data demonstrate that the apoptotic machinery regulates the biochemical properties of DRP1 during cell death.
authors.affiliation: University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: Sylwia
authors.initials: S
authors.lastname: Wasiak
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Zunino
authors.forename: Heidi M
authors.initials: HM
authors.lastname: McBride
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D034281:Dynamins; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D038761:Photobleaching; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D021381:Protein Transport / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D025842:SUMO-1 Protein / Q000378:metabolism*; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000378:metabolism*
chemical_list: C494772:BAK1 protein, human; C476525:FIS1 protein, human; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D024101:Mitochondrial Proteins; D011993:Recombinant Fusion Proteins; D025842:SUMO-1 Protein; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D049452:Green Fluorescent Proteins; D020558:GTP Phosphohydrolases; C110768:DNM1L protein, human; D034281:Dynamins