title: Mitochondrial autophagy in cells with mtDNA mutations results from synergistic loss of transmembrane potential and mTORC1 inhibition.
abstract: Autophagy has emerged as a key cellular process for organellar quality control, yet this pathway apparently fails to eliminate mitochondria containing pathogenic mutations in mitochondrial DNA (mtDNA) in patients with a variety of human diseases. In order to explore how mtDNA-mediated mitochondrial dysfunction interacts with endogenous autophagic pathways, we examined autophagic status in a panel of human cytoplasmic hybrid (cybrid) cell lines carrying a variety of pathogenic mtDNA mutations. We found that both genetic- and chemically induced loss of mitochondrial transmembrane potential (Δψ(m)) caused recruitment of the pro-mitophagic factor Parkin to mitochondria. Strikingly, however, the loss of Δψ(m) alone was insufficient to prompt delivery of mitochondria to the autophagosome (mitophagy). We found that mitophagy could be induced following treatment with the mTORC1 inhibitor rapamycin in cybrids carrying either large-scale partial deletions of mtDNA or complete depletion of mtDNA. Further, we found that the level of endogenous Parkin is a crucial determinant of mitophagy. These results suggest a two-hit model, in which the synergistic induction of both (i) mitochondrial recruitment of Parkin following the loss of Δψ(m) and (ii) mTORC1-controlled general macroautophagy is required for mitophagy. It appears that mitophagy can be accomplished by the endogenous autophagic machinery, but requires the full engagement of both of these pathways.
authors.affiliation: Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Gilkerson
authors.forename: Rosa L A
authors.initials: RL
authors.lastname: De Vries
authors.forename: Paul
authors.initials: P
authors.lastname: Lebot
authors.forename: Jakob D
authors.initials: JD
authors.lastname: Wikstrom
authors.forename: Edina
authors.initials: E
authors.lastname: Torgyekes
authors.forename: Orian S
authors.initials: OS
authors.lastname: Shirihai
authors.forename: Serge
authors.initials: S
authors.lastname: Przedborski
authors.forename: Eric A
authors.initials: EA
authors.lastname: Schon
mesh_terms: D001343:Autophagy; D045744:Cell Line, Tumor; D004272:DNA, Mitochondrial / Q000235:genetics*; D006801:Humans; D000076222:Mechanistic Target of Rapamycin Complex 1; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000502:physiology*; D046912:Multiprotein Complexes; D009154:Mutation; D010588:Phagosomes / Q000502:physiology; D011506:Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: D004272:DNA, Mitochondrial; D046912:Multiprotein Complexes; D011506:Proteins; D044767:Ubiquitin-Protein Ligases; C111567:parkin protein; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus
references.citation: Nat Cell Biol. 2010 Sep;12(9):836-41
references.pmid: 20811356
references.citation: Nat Genet. 2006 May;38(5):515-7
references.pmid: 16604074
references.citation: J Biol Chem. 2000 Apr 14;275(15):11075-81
references.pmid: 10753912
references.citation: PLoS One. 2011 Mar 08;6(3):e16746
references.pmid: 21408142
references.citation: Ann Neurol. 2004 Nov;56(5):662-9
references.pmid: 15389892
references.citation: J Biol Chem. 2006 Sep 15;281(37):27643-52
references.pmid: 16847060
references.citation: EMBO J. 2008 Jan 23;27(2):433-46
references.pmid: 18200046
references.citation: Biochim Biophys Acta. 2008 Sep;1777(9):1092-7
references.pmid: 18519024
references.citation: Nature. 1981 Apr 9;290(5806):457-65
references.pmid: 7219534
references.citation: Mol Cell. 2010 Oct 22;40(2):310-22
references.pmid: 20965424
references.citation: Methods Cell Biol. 2007;80:809-12
references.pmid: 17445723
references.citation: Proc Natl Acad Sci U S A. 2010 Jun 29;107(26):11835-40
references.pmid: 20547844
references.citation: EMBO J. 1982;1(11):1347-52
references.pmid: 6765194
references.citation: Free Radic Biol Med. 2008 Sep 15;45(6):820-5
references.pmid: 18619530
references.citation: Nat Genet. 2006 May;38(5):518-20
references.pmid: 16604072
references.citation: Mol Biol Cell. 2000 Jul;11(7):2349-58
references.pmid: 10888673
references.citation: Curr Opin Cell Biol. 2005 Dec;17(6):596-603
references.pmid: 16226444
references.citation: J Cell Biol. 2008 Dec 1;183(5):795-803
references.pmid: 19029340
references.citation: Cell. 2010 Feb 5;140(3):313-26
references.pmid: 20144757
references.citation: Nat Cell Biol. 2010 Feb;12(2):119-31
references.pmid: 20098416
references.citation: Brain. 2009 Jul;132(Pt 7):1795-809
references.pmid: 19052140
references.citation: Nature. 2006 Jun 29;441(7097):1157-61
references.pmid: 16672980
references.citation: Cell. 2002 Jul 26;110(2):163-75
references.pmid: 12150925
references.citation: PLoS One. 2009;4(3):e4756
references.pmid: 19270741
references.citation: Mol Cell Biol. 1992 Feb;12(2):480-90
references.pmid: 1732728
references.citation: PLoS Biol. 2010 Jan 26;8(1):e1000298
references.pmid: 20126261
references.citation: Mol Cell Biol. 2005 Feb;25(3):1025-40
references.pmid: 15657430
references.citation: Science. 1989 Oct 27;246(4929):500-3
references.pmid: 2814477
references.citation: Biochem J. 2004 Dec 1;384(Pt 2):287-93
references.pmid: 15324306
references.citation: Nature. 1998 Apr 9;392(6676):605-8
references.pmid: 9560156
references.citation: N Engl J Med. 2003 Jun 26;348(26):2656-68
references.pmid: 12826641
references.citation: J Membr Biol. 2000 May 1;175(1):53-62
references.pmid: 10811967
references.citation: Hum Mol Genet. 2011 May 1;20(9):1726-37
references.pmid: 21296869
references.citation: J Neurosci. 2010 Jan 20;30(3):1166-75
references.pmid: 20089925
references.citation: Science. 2004 May 21;304(5674):1158-60
references.pmid: 15087508
references.citation: J Cell Biol. 2008 Jun 30;181(7):1117-28
references.pmid: 18573913
references.citation: J Membr Biol. 1985;83(3):251-9
references.pmid: 3999123
references.citation: Cell Death Differ. 2005 Nov;12 Suppl 2:1484-9
references.pmid: 16247496
references.citation: Methods Enzymol. 2009;452:131-41
references.pmid: 19200880
references.citation: Mol Biol Cell. 2009 Apr;20(7):1992-2003
references.pmid: 19225151
references.citation: J Biol Chem. 2009 May 15;284(20):13843-13855
references.pmid: 19279012
references.citation: J Neurochem. 1999 Apr;72(4):1457-65
references.pmid: 10098849
references.citation: Hum Mol Genet. 2004 Apr 15;13(8):869-79
references.pmid: 14998933
references.citation: J Cell Biol. 2008 Oct 6;183(1):101-16
references.pmid: 18838554
references.citation: Am J Physiol Cell Physiol. 2011 Feb;300(2):C308-17
references.pmid: 21106691
references.citation: Proc Natl Acad Sci U S A. 2011 Aug 2;108(31):12937-42
references.pmid: 21768369
references.citation: Proc Natl Acad Sci U S A. 2010 Jan 5;107(1):378-83
references.pmid: 19966284
references.citation: Hum Mol Genet. 2011 Mar 1;20(5):927-40
references.pmid: 21147754
references.citation: Curr Biol. 2004 Jul 27;14(14):1296-302
references.pmid: 15268862