title: Actin and myosin contribute to mammalian mitochondrial DNA maintenance.
abstract: Mitochondrial DNA maintenance and segregation are dependent on the actin cytoskeleton in budding yeast. We found two cytoskeletal proteins among six proteins tightly associated with rat liver mitochondrial DNA: non-muscle myosin heavy chain IIA and β-actin. In human cells, transient gene silencing of MYH9 (encoding non-muscle myosin heavy chain IIA), or the closely related MYH10 gene (encoding non-muscle myosin heavy chain IIB), altered the topology and increased the copy number of mitochondrial DNA; and the latter effect was enhanced when both genes were targeted simultaneously. In contrast, genetic ablation of non-muscle myosin IIB was associated with a 60% decrease in mitochondrial DNA copy number in mouse embryonic fibroblasts, compared to control cells. Gene silencing of β-actin also affected mitochondrial DNA copy number and organization. Protease-protection experiments and iodixanol gradient analysis suggest some β-actin and non-muscle myosin heavy chain IIA reside within human mitochondria and confirm that they are associated with mitochondrial DNA. Collectively, these results strongly implicate the actomyosin cytoskeleton in mammalian mitochondrial DNA maintenance.
authors.affiliation: MRC Mitochondrial Biology Unit, Cambridge, UK.
authors.forename: A
authors.initials: A
authors.lastname: Reyes
authors.forename: J
authors.initials: J
authors.lastname: He
authors.forename: C C
authors.initials: CC
authors.lastname: Mao
authors.forename: L J
authors.initials: LJ
authors.lastname: Bailey
authors.forename: M
authors.initials: M
authors.lastname: Di Re
authors.forename: H
authors.initials: H
authors.lastname: Sembongi
authors.forename: L
authors.initials: L
authors.lastname: Kazak
authors.forename: K
authors.initials: K
authors.lastname: Dzionek
authors.forename: J B
authors.initials: JB
authors.lastname: Holmes
authors.forename: T J
authors.initials: TJ
authors.lastname: Cluett
authors.forename: M E
authors.initials: ME
authors.lastname: Harbour
authors.forename: I M
authors.initials: IM
authors.lastname: Fearnley
authors.forename: R J
authors.initials: RJ
authors.lastname: Crouch
authors.forename: M A
authors.initials: MA
authors.lastname: Conti
authors.forename: R S
authors.initials: RS
authors.lastname: Adelstein
authors.forename: J E
authors.initials: JE
authors.lastname: Walker
authors.forename: I J
authors.initials: IJ
authors.lastname: Holt
mesh_terms: D000199:Actins / Q000032:analysis / Q000037:antagonists & inhibitors / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D020868:Gene Silencing; D006801:Humans; D051379:Mice; D008928:Mitochondria / Q000737:chemistry / Q000648:ultrastructure; D024101:Mitochondrial Proteins / Q000302:isolation & purification; D018995:Myosin Heavy Chains / Q000037:antagonists & inhibitors / Q000502:physiology*; D024507:Nonmuscle Myosin Type IIA / Q000032:analysis / Q000037:antagonists & inhibitors / Q000502:physiology*; D024501:Nonmuscle Myosin Type IIB / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats
chemical_list: D000199:Actins; D004272:DNA, Mitochondrial; D024101:Mitochondrial Proteins; D024507:Nonmuscle Myosin Type IIA; D024501:Nonmuscle Myosin Type IIB; C103815:nonmuscle myosin type IIB heavy chain; D018995:Myosin Heavy Chains