title: LRPPRC mutation suppresses cytochrome oxidase activity by altering mitochondrial RNA transcript stability in a mouse model.
abstract: LRPPRC (leucine-rich pentatricopeptide repeat-containing) has been shown to be essential for the maturation of COX (cytochrome c oxidase), possibly by stabilizing RNA transcripts of COXI, COXII and COXIII genes encoded in mtDNA (mitochondrial DNA). We established a mouse 'gene-trap' model using ES cells (embryonic stem cells) in which the C-terminus of LRPPRC has been replaced with a β-geo construct. Mice homozygous for this modification were found to be subject to embryonic lethality, with death before 12.5 dpc (days post-coitum). Biochemical analysis of MEFs (mouse embryonic fibroblasts) isolated from homozygous mutants showed a major decrease in COX activity, with slight reductions in other respiratory chain complexes with mtDNA encoded components. Constructs of LRPPRC containing different numbers of PPRs (pentatricopeptide repeats) were expressed as recombinant proteins and tested for their ability to bind to the COXI mRNA transcript. Full binding required the first 19 PPR motifs. A specific segment of COXI mRNA was identified as the binding target for LRPPRC, encoded by mouse mtDNA nucleotides 5961-6020. These data strongly suggest that LRPPRC is involved in the maturation of COX, and is involved in stabilizing of mitochondrial mRNAs encoding COX transcripts.
authors: Genetics and Genome Biology, The Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, ON, Canada M5G 1X8.
authors: Fenghao
authors: F
authors: Xu
authors: Jane B L
authors: JB
authors: Addis
authors: Jessie M
authors: JM
authors: Cameron
authors: Brian H
authors: BH
authors: Robinson
mesh_terms: D000818:Animals; D002460:Cell Line; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian; D053595:Embryonic Stem Cells; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D005838:Genotype; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D047492:Peroxisome Proliferator-Activated Receptors / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D012313:RNA / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D004272:DNA, Mitochondrial; C486222:Lrpprc protein, mouse; D024101:Mitochondrial Proteins; D009363:Neoplasm Proteins; C532970:PTCD2 protein, mouse; D047492:Peroxisome Proliferator-Activated Receptors; D016601:RNA-Binding Proteins; C544451:SLIRP protein, mouse; D012313:RNA; D003576:Electron Transport Complex IV; D001616:beta-Galactosidase