ABSTRACT

Epidermal growth factor-like domain multiple 6 (Egfl6) is a basement membrane protein and plays an important role in hair follicle morphogenesis, angiogenesis, notochord development in vertebrates. Although egfl6 expression in the developing head was observed in zebrafish, its role for craniofacial development and the determination of the pharyngeal region expressing egfl6, have not been reported yet. Here, we report the expression patterns and function of egfl6 in craniofacial development in zebrafish. egfl6 was expressed sequentially in the developing pharyngeal pouches that are key epithelial structures governing the development of the vertebrate head. However, loss-of-function mutations in egfl6 did not cause any craniofacial defects, including the pouches as well as the thymus and facial cartilages whose development is contingent upon appropriate pouch formation. egfl6 was unlikely redundant with egfl7 expressed in a distinct pharyngeal region from that of egfl6 in craniofacial development because reduction of egfl7 with a MO in egfl6 mutants did not affect craniofacial development. In addition, we found that egfl6 carried an endogenous start loss mutation in the wild-type Tübingen strain, implying egfl6 would be a non-functional gene. Taken all together, we suggest that egfl6 expression in the pharyngeal pouches is not required for craniofacial development in zebrafish.

摘要

表皮生长因子样结构域多 6 (Egfl6) 是一种基底膜蛋白，在脊椎动物的毛囊形态发生、血管生成、脊索发育中起重要作用。尽管在斑马鱼中观察到发育头部的egfl6表达，但尚未报道其对颅面发育和咽部表达egfl6区域的作用。在这里，我们报告了egfl6在斑马鱼颅面发育中的表达模式和功能。egfl6在发育中的咽囊中依次表达，咽囊是控制脊椎动物头部发育的关键上皮结构。然而，egfl6中的功能丧失突变没有导致任何颅面缺陷，包括小袋以及胸腺和面部软骨，其发育取决于适当的小袋形成。egfl6不太可能与egfl7在颅面发育中的egfl6不同的咽部区域表达冗余，因为egfl6突变体中用 MO减少egfl7不会影响颅面发育。此外，我们发现egfl6在野生型 Tübingen 菌株中携带内源性起始丢失突变，这意味着egfl6将是一个无功能基因。综上所述，我们建议egfl6 斑马鱼的颅面发育不需要咽囊中的表达。