title: Fyn kinase regulates translation in mammalian mitochondria.
abstract: Mitochondrial translation machinery solely exists for the synthesis of 13 mitochondrially-encoded subunits of the oxidative phosphorylation (OXPHOS) complexes in mammals. Therefore, it plays a critical role in mitochondrial energy production. However, regulation of the mitochondrial translation machinery is still poorly understood. In comprehensive proteomics studies with normal and diseased tissues and cell lines, we and others have found the majority of mitochondrial ribosomal proteins (MRPs) to be phosphorylated. Neither the kinases for these phosphorylation events nor their specific roles in mitochondrial translation are known.
  
  
  
  Mitochondrial kinases are responsible for phosphorylation of MRPs enriched from bovine mitoplasts by strong cation-exchange chromatography and identified by mass spectrometry-based proteomics analyses of kinase rich fractions. Phosphorylation of recombinant MRPs and 55S ribosomes was assessed by in vitro phosphorylation assays using the kinase-rich fractions. The effect of identified kinase on OXPHOS and mitochondrial translation was assessed by various cell biological and immunoblotting approaches.
  
  
  
  Here, we provide the first evidence for the association of Fyn kinase, a Src family kinase, with mitochondrial translation components and its involvement in phosphorylation of 55S ribosomal proteins in vitro. Modulation of Fyn expression in human cell lines has provided a link between mitochondrial translation and energy metabolism, which was evident by the changes in 13 mitochondrially encoded subunits of OXPHOS complexes.
  
  
  
  Our findings suggest that Fyn kinase is part of a complex mechanism that regulates protein synthesis and OXPHOS possibly by tyrosine phosphorylation of translation components in mammalian mitochondria.
authors.affiliation: Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25755, United States. Electronic address: koce@marshall.edu.
authors.forename: Emine C
authors.initials: EC
authors.lastname: Koc
authors.affiliation: Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, United States.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Miller-Lee
authors.affiliation: Department of Pharmaceutical Science and Research, School of Pharmacy, Marshall University, Huntington, WV 25755, United States. Electronic address: kocha@marshall.edu.
authors.forename: Hasan
authors.initials: H
authors.lastname: Koc
mesh_terms: D000818:Animals; D002417:Cattle; D002460:Cell Line; D045744:Cell Line, Tumor; D057809:HEK293 Cells; D056945:Hep G2 Cells; D006801:Humans; D015151:Immunoblotting / Q000379:methods; D008322:Mammals / Q000378:metabolism* / Q000502:physiology*; D008928:Mitochondria / Q000378:metabolism* / Q000502:physiology*; D024101:Mitochondrial Proteins / Q000378:metabolism*; D000069396:Mitochondrial Ribosomes / Q000378:metabolism / Q000502:physiology; D010085:Oxidative Phosphorylation; D010766:Phosphorylation / Q000502:physiology; D014176:Protein Biosynthesis / Q000502:physiology*; D040901:Proteomics / Q000379:methods; D051076:Proto-Oncogene Proteins c-fyn / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000378:metabolism
chemical_list: D024101:Mitochondrial Proteins; D012269:Ribosomal Proteins; D051076:Proto-Oncogene Proteins c-fyn
keywords: Fyn kinase; Mitochondrial protein synthesis (translation); Mitochondrial ribosomal proteins (MRPs); Tyrosine phosphorylation