title: RNA subunit of mitochondrial RNA-processing enzyme is induced by contractile activity in striated muscle.
abstract: A small RNA encoded within the nucleus of yeast and mammalian cells is an essential subunit of a mitochondrial RNA-processing endonuclease (RNase MRP) that generates primers for mitochondrial DNA (mtDNA) replication. We examined expression of MRP-RNA in specialized subtypes of mammalian striated muscles that differ markedly in respiratory activity and in muscles subjected to chronic stimulation via the motor nerve, a potent stimulus to mitochondrial biogenesis. MRP-RNA was more abundant in mitochondria-rich cardiac and slow-twitch skeletal muscles than in glycolytic fast-twitch skeletal muscles. Forced contractile activity resulting from nerve stimulation increased expression of MRP-RNA by 3.5-fold within the first day and by 14-fold within 14 days. Changes in abundance of MRP-RNA preceded but otherwise occurred in parallel to changes in specific activity of citrate synthase, a marker of mitochondrial proliferation shown previously to correlate with mtDNA copy number in this model. Another small RNA (U1) also was induced transiently (1-3 days) by nerve stimulation, but such changes were not sustained and were of less magnitude (< 4-fold) than changes in MRP-RNA. These findings are consistent with the hypothesis that MRP-RNA may have a regulatory function with respect to mtDNA replication and mitochondrial biogenesis.
authors.affiliation: Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235-8573.
authors.forename: G A
authors.initials: GA
authors.lastname: Ordway
authors.forename: K
authors.initials: K
authors.lastname: Li
authors.forename: G A
authors.initials: GA
authors.lastname: Hand
authors.forename: R S
authors.initials: RS
authors.lastname: Williams
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004261:DNA Replication; D004272:DNA, Mitochondrial / Q000096:biosynthesis; D004722:Endoribonucleases / Q000096:biosynthesis*; D004790:Enzyme Induction; D046911:Macromolecular Substances; D051379:Mice; D008931:Mitochondria, Muscle / Q000201:enzymology*; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000502:physiology*; D009132:Muscles / Q000294:innervation / Q000502:physiology*; D015345:Oligonucleotide Probes; D010543:Peroneal Nerve / Q000502:physiology; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012313:RNA / Q000032:analysis / Q000096:biosynthesis*; D011817:Rabbits; D043244:Ribonuclease III; D017384:Sequence Deletion; D016385:TATA Box; D014158:Transcription, Genetic
chemical_list: D004272:DNA, Mitochondrial; D046911:Macromolecular Substances; D015345:Oligonucleotide Probes; D012313:RNA; D004722:Endoribonucleases; D043244:Ribonuclease III