Schubert M, Holland L Z, Holland N D
Scripps Institution of Oceanography, University of California at San Diego, La Jolla 92093-0202, USA.
Dev Dyn. 2000 Feb;217(2):205-15. doi: 10.1002/(SICI)1097-0177(200002)217:2<205::AID-DVDY7>3.0.CO;2-F.
Full-length sequences and developmental expression patterns of two amphioxus Wnt genes (AmphiWnt4 and AmphiWnt7b) are described for the first time. The dynamic expression pattern of AmphiWnt4 suggests roles in the development of the posterior mesoderm, central nervous system, muscular somites, heart, and endostyle (a homolog of the vertebrate thyroid). The less diverse expression domains of AmphiWnt7b indicate that this gene may be involved only in the development of the central nervous system and the endostyle. In contrast to amphioxus, vertebrate embryos do not express Wnt4 homologues in the posterior mesoderm, somites, or heart; instead, Wnt genes of other subfamilies are expressed in these developing vertebrate organs. Because the developmental genetic programs of amphioxus may approximate those in the invertebrate chordate ancestor of the vertebrates, it is possible that some developmental functions of an ancestral Wnt4 gene may have been assumed by genes of other Wnt subfamilies during vertebrate evolution, possibly as a result of functional redundancy among Wnt subfamilies.
首次描述了两种文昌鱼Wnt基因(AmphiWnt4和AmphiWnt7b)的全长序列和发育表达模式。AmphiWnt4的动态表达模式表明其在后中胚层、中枢神经系统、肌肉体节、心脏和内柱(脊椎动物甲状腺的同源物)的发育中发挥作用。AmphiWnt7b的表达域差异较小,表明该基因可能仅参与中枢神经系统和内柱的发育。与文昌鱼不同,脊椎动物胚胎在后中胚层、体节或心脏中不表达Wnt4同源物;相反,其他亚家族的Wnt基因在这些发育中的脊椎动物器官中表达。由于文昌鱼的发育遗传程序可能与脊椎动物无脊椎动物脊索动物祖先的程序相似,因此在脊椎动物进化过程中,祖先Wnt4基因的一些发育功能可能已被其他Wnt亚家族的基因所承担,这可能是由于Wnt亚家族之间功能冗余的结果。