Contribution of the tRNA Ile 4317A→G mutation to the phenotypic manifestation of the deafness-associated mitochondrial 12S rRNA 1555A→G mutation

J Biol Chem. 2018 Mar 2;293(9):3321-3334. doi: 10.1074/jbc.RA117.000530. Epub 2018 Jan 18.

Abstract

The 1555A→G mutation in mitochondrial 12S rRNA has been associated with aminoglycoside-induced and non-syndromic deafness in many individuals worldwide. Mitochondrial genetic modifiers are proposed to influence the phenotypic expression of m.1555A→G mutation. Here, we report that a deafness-susceptibility allele (m.4317A→G) in the tRNAIle gene modulates the phenotype expression of m.1555A→G mutation. Strikingly, a large Han Chinese pedigree carrying both m.4317A→G and m.1555A→G mutations exhibited much higher penetrance of deafness than those carrying only the m.1555A→G mutation. The m.4317A→G mutation affected a highly conserved adenine at position 59 in the T-loop of tRNAIle We therefore hypothesized that the m.4317A→G mutation alters both structure and function of tRNAIle Using lymphoblastoid cell lines derived from members of Chinese families (three carrying both m.1555A→G and m.4317A→G mutations, three harboring only m.1555A→G mutation, and three controls lacking these mutations), we found that the cell lines bearing both m.4317A→G and m.1555A→G mutations exhibited more severe mitochondrial dysfunctions than those carrying only the m.1555A→G mutation. We also found that the m.4317A→G mutation perturbed the conformation, stability, and aminoacylation efficiency of tRNAIle These m.4317A→G mutation-induced alterations in tRNAIle structure and function aggravated the defective mitochondrial translation and respiratory phenotypes associated with the m.1555A→G mutation. Furthermore, mutant cell lines bearing both m.4317A→G and m.1555A→G mutations exhibited greater reductions in the mitochondrial ATP levels and membrane potentials and increasing production of reactive oxygen species than those carrying only the m.1555A→G mutation. Our findings provide new insights into the pathophysiology of maternally inherited deafness arising from the synergy between mitochondrial 12S rRNA and tRNA mutations.

Keywords: ATP; genetics; hearing; maternal inheritance; mitochondrial DNA (mtDNA); mitochondrial disease; modifier factors; mutation; pathophysiology; phenotypic expression; reactive oxygen species (ROS); respiratory chain; ribosomal ribonucleic acid (rRNA) (ribosomal RNA); transfer RNA (tRNA); translation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / biosynthesis
  • Alleles
  • Case-Control Studies
  • Cell Respiration / genetics
  • Cohort Studies
  • Deafness / genetics*
  • Deafness / metabolism
  • Deafness / pathology
  • Electron Transport Chain Complex Proteins / metabolism
  • Female
  • Genetic Predisposition to Disease / genetics
  • Humans
  • Male
  • Mitochondria / genetics
  • Mitochondria / metabolism
  • Mutation*
  • Phenotype*
  • RNA, Mitochondrial / genetics*
  • RNA, Ribosomal / genetics*
  • RNA, Transfer, Ile / genetics*
  • Reactive Oxygen Species / metabolism
  • Young Adult

Substances

  • Electron Transport Chain Complex Proteins
  • RNA, Mitochondrial
  • RNA, Ribosomal
  • RNA, Transfer, Ile
  • RNA, ribosomal, 12S
  • Reactive Oxygen Species
  • Adenosine Triphosphate