title: Mice lacking COX10 in skeletal muscle recapitulate the phenotype of progressive mitochondrial myopathies associated with cytochrome c oxidase deficiency.
abstract: We have created a mouse model with an isolated cytochrome c oxidase (COX) deficiency by disrupting the COX10 gene in skeletal muscle. Missense mutations in COX10 have been previously associated with mitochondrial disorders. Cox10p is a protoheme:heme-O-farnesyl transferase required for the synthesis of heme a, the prosthetic group of the catalytic center of COX. COX10 conditional knockout mice were generated by crossing a LoxP-tagged COX10 mouse with a transgenic mouse expressing cre recombinase under the myosin light chain 1f promoter. The COX10 knockout mice were healthy until approximately 3 months of age when they started developing a slowly progressive myopathy. Surprisingly, even though COX activity in COX10 KO muscles was <5% of control muscle at 2.5 months, these muscles were still able to contract at 80-100% of control maximal forces and showed only a 10% increase in fatigability, and no signs of oxidative damage or apoptosis were detected. However, the myopathy worsened with time, particularly in female animals. This COX10 KO mouse allowed us to correlate the muscle function with residual COX activity, an estimate that can help predict the progression pattern of human mitochondrial myopathies.
authors.affiliation: Department of Neurology, The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA.
authors.forename: Francisca
authors.initials: F
authors.lastname: Diaz
authors.forename: Christine K
authors.initials: CK
authors.lastname: Thomas
authors.forename: Sofia
authors.initials: S
authors.lastname: Garcia
authors.forename: Dayami
authors.initials: D
authors.lastname: Hernandez
authors.forename: Carlos T
authors.initials: CT
authors.lastname: Moraes
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D003433:Crosses, Genetic; D030401:Cytochrome-c Oxidase Deficiency / Q000235:genetics*; D004195:Disease Models, Animal; D018450:Disease Progression; D003576:Electron Transport Complex IV / Q000235:genetics*; D018014:Gene Transfer Techniques; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D046529:Microscopy, Electron, Transmission; D017240:Mitochondrial Myopathies / Q000235:genetics*; D015336:Molecular Probe Techniques; D018763:Muscle Fatigue / Q000235:genetics; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000648:ultrastructure; D020125:Mutation, Missense / Q000235:genetics
chemical_list: D003576:Electron Transport Complex IV