Journal Article

Correcting human mitochondrial mutations with targeted RNA import

Zhang, Jin, Koehler, Carla M, Shimada, Eriko, Teitell, Michael A, Hong, Jason S, Wang, Geng, Smith, Geoffrey M

2012

Overview

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.

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: 3' Untranslated regions / Aging / Base Sequence / Biological Sciences / Cell Line / Cell lines / Cell Respiration / chemistry / Cyclooxygenase-2 / Electron transport / Electron Transport Complex IV / Electron Transport Complex IV - genetics / Enzymes / genetic disorders / Genetic mutation / genetics / genome / Genomes / Humans / Hybrids / Imports / MELAS Syndrome / MELAS Syndrome - genetics / Mental disorders / MERRF Syndrome / MERRF Syndrome - genetics / Messenger RNA / metabolism / Mitochondria / Mitochondria - genetics / Mitochondrial DNA / Molecular Sequence Data / Mutation / Mutation - genetics / neuromuscular disorders / neutralization / Nucleic Acid Conformation / Nucleotide sequence / Outer membranes / phosphorylase / polynucleotide phosphorylase / Protein Biosynthesis / Protein Biosynthesis - genetics / Protein transport / Proteins / Regulatory sequences / Ribonuclease P / ribonucleases / Ribonucleic acid / ribosomal protein S12 / RNA / RNA - genetics / RNA Precursors / RNA Precursors - metabolism / RNA Transport / RNA Transport - genetics / RNA, Transfer / RNA, Transfer - chemistry / RNA, Transfer - metabolism / Stem cells / Transcription / Transfer RNA / Translation / translation (genetics) / Translocation / tRNA