在脊椎动物中,Fgf信号传导对于咽囊的发展至关重要,控制面部骨骼发育。基因上,fgf3和fgf8是小鼠和斑马鱼形成小袋所必需的。然而,在小鼠和斑马鱼中,fgf3和fgf8的功能丧失表型比预期的要温和,这表明一个额外的fgf基因将参与袋的形成。这里,我们分析了表达式,regulation,和三个fgfs的功能,fgf4,fgf24和fgf17,在斑马鱼的袋发育过程中。我们发现它们在囊形成的咽内胚层的不同区域表达,fgf4和fgf17也在相邻的中胚层中表达,除了先前报道的内胚层fgf3和中胚层fgf8表达。在小袋形成中,fgf4,fgf24和fgf17的内胚层表达以及fgf4和fgf17的中胚层表达受Tbx1正调节,但不受Fgf3正调节。Fgf8是表达fgf4和fgf24的内胚层表达所必需的。有趣的是,然而,单突变体,所有双突变组合,fgf4,fgf24和fgf17的三重突变体在小袋和面部骨骼中没有任何缺陷。考虑到斑马鱼颅面发育中Fgf信号成分的高度遗传冗余,我们的结果表明,fgf4,fgf24和fgf17对小袋的形成有潜在的作用,与其他fgf基因冗余。
In vertebrates, Fgf signaling is essential for the development of pharyngeal pouches, which controls facial skeletal development. Genetically, fgf3 and fgf8 are required for pouch formation in mice and zebrafish. However, loss-of-function phenotypes of fgf3 and fgf8 are milder than expected in mice and zebrafish, which suggests that an additional fgf gene(s) would be involved in pouch formation. Here, we analyzed the expression, regulation, and function of three fgfs, fgf4, fgf24, and fgf17, during pouch development in zebrafish. We find that they are expressed in the distinct regions of pharyngeal endoderm in pouch formation, with fgf4 and fgf17 also being expressed in the adjacent mesoderm, in addition to previously reported endodermal fgf3 and mesodermal fgf8 expression. The endodermal expression of fgf4, fgf24, and fgf17 and the mesodermal expression of fgf4 and fgf17 are positively regulated by Tbx1 but not by Fgf3, in pouch formation. Fgf8 is required to express the endodermal expression of fgf4 and fgf24. Interestingly, however, single mutant, all double mutant combinations, and triple mutant for fgf4, fgf24, and fgf17 do not show any defects in pouches and facial skeletons. Considering a high degree of genetic redundancy in the Fgf signaling components in craniofacial development in zebrafish, our result suggests that fgf4, fgf24, and fgf17 have a potential role for pouch formation, with a redundancy with other fgf gene(s).