Tek/Tie2 is not required for cardiovascular development in zebrafish

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 profili...

血管生成素/酪氨酸激酶受体（Angiopoietin/TIE）信号通路在血液和淋巴管发育中发挥关键作用。在小鼠中，Tek/Tie2突变体因心血管系统发育严重不全而于产前死亡。相比之下，在斑马鱼中，先前研究表明，尽管注射tek吗啉代（morpholinos，MOs）的胚胎表现出严重血管缺陷，但tek突变体未显示明显的血管畸形。为进一步探究斑马鱼Tek的功能，我们构建了一组功能缺失型（loss-of-function）tek突变体，包括无RNA等位基因、缺乏MO结合位点的等位基因、框内缺失等位基因以及含提前终止密码子的等位基因。我们的数据显示，所有这些突变体均可存活至成年且无明显心血管缺陷。向缺乏MO结合位点的tek突变体或整个tek基因座（locus）缺失的突变体注射MO，会导致与MO注射的+/+同胞相似的血管缺陷，这表明MO存在脱靶效应（off-target effects）。令人惊讶的是，全面的系统发育谱分析（phylogenetic profiling）...