TY  - JOUR
A1  - Kayvanpour, Elham
A1  - Wisdom, Michael
A1  - Lackner, Maximilian K.
A1  - Sedaghat-Hamedani, Farbod
A1  - Boeckel, Jes-Niels
A1  - Müller, Marion
A1  - Eghbalian, Rose
A1  - Dudek, Jan
A1  - Doroudgar, Shirin
A1  - Maack, Christoph
A1  - Frey, Norbert
A1  - Meder, Benjamin
T1  - VARS2 depletion leads to activation of the integrated stress response and disruptions in mitochondrial fatty acid oxidation
JF  - International Journal of Molecular Sciences
N2  - 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-of-function 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 III\(_2\), III\(_2\) + IV, and supercomplexes without significant respiratory chain deficiencies. These cells also showed the enhanced activation of the ISR, as indicated by increased eIF-2α 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.
KW  - VARS2
KW  - heart failure
KW  - integrated stress response
KW  - mitochondrial FAO
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-284590
SN  - 1422-0067
VL  - 23
IS  - 13
ER  -