title: Correcting human mitochondrial mutations with targeted RNA import.
abstract: Mutations in the human mitochondrial genome are implicated in neuromuscular diseases, metabolic defects, and aging. An efficient and simple mechanism for neutralizing deleterious mitochondrial DNA (mtDNA) alterations has unfortunately remained elusive. Here, we report that a 20-ribonucleotide stem-loop sequence from the H1 RNA, the RNA component of the human RNase P enzyme, appended to a nonimported RNA directs the import of the resultant RNA fusion transcript into human mitochondria. The methodology is effective for both noncoding RNAs, such as tRNAs, and mRNAs. The RNA import component, polynucleotide phosphorylase (PNPASE), facilitates transfer of this hybrid RNA into the mitochondrial matrix. In addition, nucleus-encoded mRNAs for mitochondrial proteins, such as the mRNA of human mitochondrial ribosomal protein S12 (MRPS12), contain regulatory sequences in their 3'-untranslated region (UTR) that confers localization to the mitochondrial outer membrane, which is postulated to aid in protein translocation after translation. We show that for some mitochondrial-encoded transcripts, such as COX2, a 3'-UTR localization sequence is not required for mRNA import, whereas for corrective mitochondrial-encoded tRNAs, appending the 3'-UTR localization sequence was essential for efficient fusion-transcript translocation into mitochondria. In vivo, functional defects in mitochondrial RNA (mtRNA) translation and cell respiration were reversed in two human disease lines. Thus, this study indicates that a wide range of RNAs can be targeted to mitochondria by appending a targeting sequence that interacts with PNPASE, with or without a mitochondrial localization sequence, providing an exciting, general approach for overcoming mitochondrial genetic disorders.
authors.affiliation: Department of Chemistry and Biochemistry, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
authors.forename: Geng
authors.initials: G
authors.lastname: Wang
authors.forename: Eriko
authors.initials: E
authors.lastname: Shimada
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.forename: Jason S
authors.initials: JS
authors.lastname: Hong
authors.forename: Geoffrey M
authors.initials: GM
authors.lastname: Smith
authors.forename: Michael A
authors.initials: MA
authors.lastname: Teitell
authors.forename: Carla M
authors.initials: CM
authors.lastname: Koehler
mesh_terms: D001483:Base Sequence; D002460:Cell Line; D019069:Cell Respiration; D003576:Electron Transport Complex IV / Q000235:genetics; D006801:Humans; D017241:MELAS Syndrome / Q000235:genetics; D017243:MERRF Syndrome / Q000235:genetics; D008928:Mitochondria / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis / Q000235:genetics; D012313:RNA / Q000235:genetics; D012322:RNA Precursors / Q000378:metabolism; D034443:RNA Transport / Q000235:genetics*; D000077278:RNA, Mitochondrial; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism
chemical_list: D012322:RNA Precursors; D000077278:RNA, Mitochondrial; D012313:RNA; D012343:RNA, Transfer; D003576:Electron Transport Complex IV