首先在马利筋虫Oncopeltusfasciatus中描述,平面细胞极性(PCP)是后生动物胚胎发生和极化结构发育所必需的发育过程。该信号通路涉及一组编码跨膜(Vangl,卷曲,Celsr)和胞质(刺梨,不均匀)分子。Vangl2在胚胎发育中具有重要意义,如它在人类神经管闭合过程中的关键作用所示,鼠标,非洲爪狼,和斑马鱼胚胎。这里,我们报道了Vangl2亚型的分子和功能表征,Vangl2-Long,含有大约50aa的N端延伸,它来自另一个接近同源的AUA翻译起始位点,位于常规起始密码子的上游。虽然在Vangl1类目和所有无脊椎动物中缺失,包括果蝇,该N-末端延伸在所有脊椎动物Vangl2序列中是保守的。我们证明Vangl2-Long属于具有Vangl1和Vangl2的多聚体复合物。使用吗啉代寡核苷酸特异性敲除非洲爪狼中的Vangl2-Long,我们发现这种同工型是功能性的,是胚胎延伸和神经管闭合所必需的。此外,对于有纤毛的表皮细胞中PCP分子Pk2和Dvl1的极化分布以及中心粒旋转极性,必须正确表达Vangl2和Vangl2-Long。总之,我们的研究表明,Vangl2-Long显着有助于质膜上存在的Vangl2分子库,以维持脊椎动物组织中的PCP。
First described in the milkweed bug Oncopeltus fasciatus, planar cell polarity (PCP) is a developmental process essential for embryogenesis and development of polarized structures in Metazoans. This signaling pathway involves a set of evolutionarily conserved genes encoding transmembrane (Vangl, Frizzled, Celsr) and cytoplasmic (Prickle, Dishevelled) molecules.
Vangl2 is of major importance in embryonic development as illustrated by its pivotal role during neural tube closure in human, mouse, Xenopus, and zebrafish embryos. Here, we report on the molecular and functional characterization of a
Vangl2 isoform,
Vangl2-Long, containing an N-terminal extension of about 50 aa, which arises from an alternative near-cognate AUA translation initiation site, lying upstream of the conventional start codon. While missing in Vangl1 paralogs and in all invertebrates, including Drosophila, this N-terminal extension is conserved in all vertebrate Vangl2 sequences. We show that
Vangl2-Long belongs to a multimeric complex with Vangl1 and
Vangl2. Using morpholino oligonucleotides to specifically knockdown Vangl2-Long in Xenopus, we found that this isoform is functional and required for embryo extension and neural tube closure. Furthermore, both
Vangl2 and
Vangl2-Long must be correctly expressed for the polarized distribution of the PCP molecules Pk2 and Dvl1 and for centriole rotational polarity in ciliated epidermal cells. Altogether, our study suggests that
Vangl2-Long significantly contributes to the pool of
Vangl2 molecules present at the plasma membrane to maintain PCP in vertebrate tissues.