An animal model for mitochondrial tyrosyl-tRNA synthetase deficiency reveals links between oxidative phosphorylation and retinal function.

Abstract

Mitochondria maintain a distinct pool of ribosomal machinery, including tRNAs and tRNAs activating enzymes, such as mitochondrial tyrosyl-tRNA synthetase (YARS2). Mutations in YARS2, which typically lead to the impairment of mitochondrial protein synthesis, have been linked to an array of human diseases including optic neuropathy. However, the lack of YARS2 mutation animal model makes us difficult to elucidate the pathophysiology underlying YARS2 deficiency. To explore this system, we generated YARS2 knockout (KO) HeLa cells and zebrafish using CRISPR/Cas9 technology. We observed the aberrant tRNATyr aminoacylation overall and reductions in the levels in mitochondrion- and nucleus-encoding subunits of oxidative phosphorylation system (OXPHOS), which were especially pronounced effects in the subunits of complex I and complex IV. These deficiencies manifested the decreased levels of intact supercomplexes overall. Immunoprecipitation assays showed that YARS2 bound to specific subunits of complex I and complex IV, suggesting the posttranslational stabilization of OXPHOS. Furthermore, YARS2 ablation caused defects in the stability and activities of OXPHOS complexes. These biochemical defects could be rescued by the overexpression of YARS2 cDNA in the YARS2KO cells. In zebrafish, the yars2KO larva conferred deficient COX activities in the retina, abnormal mitochondrial morphology, and numbers in the photoreceptor and retinal ganglion cells. The zebrafish further exhibited the retinal defects affecting both rods and cones. Vision defects in yars2KO zebrafish recapitulated the clinical phenotypes in the optic neuropathy patients carrying the YARS2 mutations. Our findings highlighted the critical role of YARS2 in the stability and activity of OXPHOS and its pathological consequence in vision impairments.

• Authors: Xiaofen Jin, Zengming Zhang, Zhipeng Nie, Chenghui Wang, Feilong Meng, Qiuzi Yi, Mengquan Chen, Jiji Sun, Jian Zou, Pingping Jiang, Min-Xin Guan
• Journal: The Journal of biological chemistry (J Biol Chem) 2021 Jan-Jun Vol. 296 Pg. 100437 ISSN: 1083-351X [Electronic] United States
• PMID: 33610547 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.

Chemical References

• Mitochondrial Proteins
• Zebrafish Proteins
• Electron Transport Complex IV
• Tyrosine-tRNA Ligase
• Electron Transport Complex I

Topics

• Animals
• CRISPR-Cas Systems
• Electron Transport Complex I (genetics, metabolism)
• Electron Transport Complex IV (genetics, metabolism)
• Gene Knockout Techniques
• HeLa Cells
• Humans
• Mitochondrial Proteins (genetics, metabolism)
• Oxidative Phosphorylation
• Retina (enzymology)
• Tyrosine-tRNA Ligase (deficiency, metabolism)
• Zebrafish (genetics, metabolism)
• Zebrafish Proteins (genetics, metabolism)