Tek/Tie2 is not required for cardiovascular development in zebrafish

Abstract

Angiopoietin/TIE signalling plays a major role in blood and lymphatic vessel development. In mouse, Tek/Tie2 mutants die prenatally due to a severely underdeveloped cardiovascular system. In contrast, in zebrafish, previous studies have reported that while embryos injected with tek morpholinos (MOs) exhibit severe vascular defects, tek mutants display no obvious vascular malformations. To further investigate the function of zebrafish Tek, we generated a panel of loss-of-function tek mutants, including RNA-less alleles, an allele lacking the MO-binding site, an in-frame deletion allele, and a premature termination codon-containing allele. Our data show that all these mutants survive to adulthood with no obvious cardiovascular defects. MO injections into tek mutants lacking the MO-binding site or the entire tek locus cause similar vascular defects as those observed in MO-injected +/+ siblings, indicating off-target effects of the MOs. Surprisingly, comprehensive phylogenetic profiling and synteny analyses reveal that Tek was lost in the largest teleost clade, suggesting a lineage-specific shift in the function of TEK during vertebrate evolution. Altogether, these data show that Tek is dispensable for zebrafish development, and probably dispensable in most teleost species.

Angiopoietin 1 and integrin beta 1b are vital for zebrafish brain development

“…Our present data show for the first-time in vivo evidence that angpt1 and itgb1b play not only essential roles in developing cerebrovascular formation but exert also own neurogenic effects on the development of different neural cell populations, including dopaminergic, histaminergic, and GABAergic systems, and the patterning of hindbrain reticulospinal neurons in the CNS. Our novel findings also provide evidence that the role of tek is dispensable in embryonic neurogenesis in zebrafish, similar to the published results in angiogenesis (Gjini et al, 2011; Jiang et al, 2020).…”

“…Unlike the gross cardiovascular phenotype appearing in the angpt1 sa14264 mutant and reported itgb1b mi371 mutant (Iida et al, 2018), the tek hu1667 mutant fish grow naturally without overt cardiovascular defects (Gjini et al, 2011; Jiang et al, 2020). It has been reported that besides Tek, Angpt1 can bind to integrins and activate similar pathways as the angpt1-tek does (Chen et al, 2009a), which renders it possible that the angpt1-itgb1b signaling pathway may play a more vital role than the recognized angpt1-tek pathway in the regulation of embryogenesis.…”

Tracing Eukaryotic Ribosome Biogenesis Factors Into the Archaeal Domain Sheds Light on the Evolution of Functional Complexity

“…RBF orthologs were identified with the targeted ortholog search tool fDog ( Jiang et al, 2020 ) 2 using the following parameter settings: –checkCoorthologsRef, −-countercheck, −-minDist=family, and −-maxDist=kingdom. Protein domain architectures were compared pair-wise between each seed protein and its orthologs, and an architecture similarity score was computed with FAS 3 implemented into fDOG.…”

“…The latter problem can be ameliorated by scoring the similarity of protein domain architectures ( Koestler et al, 2010 ), which comprise features, such as Pfam ( El-Gebali et al, 2019 ) or Smart ( Letunic et al, 2009 ) domains, transmembrane regions, signal peptides, or regions of biased amino acid composition. Differences in domain architectures can then indicate alterations in the respective functional spectra of the compared proteins ( Jiang et al, 2020 ). In contrast to the ample means to cope with the spurious inference of archaeal RBF candidates based on homologous proteins, false negatives, i.e., proteins overlooked in the homolog searches because their sequences have diverged to an extent that they are no more similar than it is expected by chance, have received very little attention.…”

The Zebrafish Cardiac Endothelial Cell—Roles in Development and Regeneration

“…This caused a significant shift in how morpholinos are used in the laboratory [ 15 ] and promoted the adoption of CRISPR/Cas9 and similar gene editing techniques to create mutant allele-harbouring zebrafish lines. Their study also prompted a more nuanced understanding of what underlying biological mechanisms can cause this discrepancy, ranging from within-pathway compensation to cellular stress response and evolutionary divergence of protein function [ 16 , 17 , 18 , 19 ].…”