Mutations in mitochondrial aminoacyl-tRNA synthetases (mtARSs) have been reported
in patients with mitochondriopathies: most commonly encephalopathy, but also cardiomyopathy.
Through a GWAS, we showed possible associations between mitochondrial valyl-tRNA synthetase
(VARS2) dysregulations and non-ischemic cardiomyopathy. We aimed to investigate the possible
consequences of VARS2 depletion in zebrafish and cultured HEK293A cells. Transient VARS2 loss-offunction
was induced in zebrafish embryos using Morpholinos. The enzymatic activity of VARS2
was measured in VARS2-depleted cells via northern blot. Heterozygous VARS2 knockout was
established in HEK293A cells using CRISPR/Cas9 technology. BN-PAGE and SDS-PAGE were used
to investigate electron transport chain (ETC) complexes, and the oxygen consumption rate and
extracellular acidification rate were measured using a Seahorse XFe96 Analyzer. The activation of
the integrated stress response (ISR) and possible disruptions in mitochondrial fatty acid oxidation
(FAO) were explored using RT-qPCR and western blot. Zebrafish embryos with transient VARS2
loss-of-function showed features of heart failure as well as indications of CNS and skeletal muscle
involvements. The enzymatic activity of VARS2 was significantly reduced in VARS2-depleted
cells. Heterozygous VARS2-knockout cells showed a rearrangement of ETC complexes in favor of
complexes III2, III2 + IV, and supercomplexes without significant respiratory chain deficiencies. These
cells also showed the enhanced activation of the ISR, as indicated by increased eIF-2 phosphorylation
and a significant increase in the transcript levels of ATF4, ATF5, and DDIT3 (CHOP), as well as
disruptions in FAO. The activation of the ISR and disruptions in mitochondrial FAO may underlie
the adaptive changes in VARS2-depleted cells.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:89636 |
| Date | 09 February 2024 |
| Creators | Kayvanpour, Elham, Wisdom, Michael, Lackner, Maximilian K., Sedaghat-Hamedani, Farbod, Boeckel, Jes-Niels, Müller, Marion, Eghbalian, Rose, Dudek, Jan, Doroudgar, Shirin, Maack, Christoph, Frey, Norbert, Meder, Benjamin |
| Publisher | MDPI |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:article, info:eu-repo/semantics/article, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 7327 |
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