title: Mitochondrial fission and fusion factors reciprocally orchestrate mitophagic culling in mouse hearts and cultured fibroblasts.
abstract: How mitochondrial dynamism (fission and fusion) affects mitochondrial quality control is unclear. We uncovered distinct effects on mitophagy of inhibiting Drp1-mediated mitochondrial fission versus mitofusin-mediated mitochondrial fusion. Conditional cardiomyocyte-specific Drp1 ablation evoked mitochondrial enlargement, lethal dilated cardiomyopathy, and cardiomyocyte necrosis. Conditionally ablating cardiomyocyte mitofusins (Mfn) caused mitochondrial fragmentation with eccentric remodeling and no cardiomyocyte dropout. Parallel studies in cultured murine embryonic fibroblasts (MEFs) and in vivo mouse hearts revealed that Mfn1/Mfn2 deletion provoked accumulation of defective mitochondria exhibiting an unfolded protein response, without appropriately increasing mitophagy. Conversely, interrupting mitochondrial fission by Drp1 ablation increased mitophagy and caused a generalized loss of mitochondria. Mitochondrial permeability transition pore (MPTP) opening in Drp1 null mitochondria was associated with mitophagy in MEFs and contributed to cardiomyocyte necrosis and dilated cardiomyopathy in mice. Drp1, MPTP, and cardiomyocyte mitophagy are functionally integrated. Mitochondrial fission and fusion have opposing roles during in vivo cardiac mitochondrial quality control.
authors.affiliation: Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Moshi
authors.initials: M
authors.lastname: Song
authors.affiliation: Department of Molecular Biology, Kyushu University, Fukuoka 812-8582, Japan.
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Mihara
authors.affiliation: Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Yun
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Dulbecco-Telethon Institute, Venetian Institute of Molecular Medicine and Department of Biology, University of Padua, Padova 35129, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Scorrano
authors.affiliation: Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA. Electronic address: gdorn@dom.wustl.edu.
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Dorn
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D034281:Dynamins / Q000172:deficiency / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology*; D020558:GTP Phosphohydrolases / Q000172:deficiency / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008929:Mitochondria, Heart / Q000378:metabolism*; D063154:Mitochondrial Dynamics; D063306:Mitophagy; D009206:Myocardium / Q000166:cytology*
chemical_list: D020558:GTP Phosphohydrolases; C488750:Mfn1 protein, mouse; C488751:Mfn2 protein, mouse; C486391:Dnm1l protein, mouse; D034281:Dynamins