Developmental Angiogenesis Requires the Mitochondrial Phenylalanyl-tRNA Synthetase.

Mitochondrial aminoacyl-tRNA synthetases (mtARSs) catalyze the binding of specific amino acids to their cognate tRNAs and play an essential role in the synthesis of proteins encoded by mitochondrial DNA. Defects in mtARSs have been linked to human diseases, but their tissue-specific pathophysiology remains elusive. Here we examined the role of mitochondrial phenylalanyl-tRNA synthetase (FARS2) in developmental angiogenesis and its potential contribution to the pathogenesis of cardiovascular disease. Morpholinos were injected into fertilized zebrafish ova to establish an knock-down model. A visualization of the vasculature was achieved by using transgenic zebrafish. In addition, small interference RNAs (siRNAs) were transferred into human umbilical vein endothelial cells (HUVECs) to establish an knock-down model. Cell motility, proliferation, and tubulogenesis were determined using scratch-wound CCK8, transwell-based migration, and tube formation assays. In addition, mitochondria- and non-mitochondria-related respiration were evaluated using a Seahorse XF24 analyzer and flow cytometry assays. Analyses of the expression levels of transcripts and proteins were performed using qRT-PCR and western blotting, respectively. The knock-down of hampered the embryonic development in zebrafish and delayed the formation of the vasculature in transgenic zebrafish. In addition, the siRNA-mediated knock-down of impaired angiogenesis in HUVECs as indicated by decreased cell motility and tube formation capacity. The knock-down of also produced variable decreases in mitochondrial- and non-mitochondrial respiration in HUVECs and disrupted the regulatory pathways of angiogenesis in both HUVECs and zebrafish. Our current work offers novel insights into angiogenesis defects and cardiovascular diseases induced by deficiency.