Lin Hsiu-Chin, Holland Linda Z, Holland Nicholas D
Marine Biology Research Division, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92093, USA.
Dev Dyn. 2006 Dec;235(12):3396-403. doi: 10.1002/dvdy.20971.
T-cell factor (TCF) and lymphoid enhancer factors (LEF) genes encode proteins that are transcription factors mediating beta-catenin/Wnt signaling. Whereas mammals have four such genes, the Florida amphioxus (Branchiostoma floridae) apparently has only one such gene (AmphiTcf). From cleavage through early gastrula, cytoplasmic maternal transcripts of this gene are localized toward the animal pole. In gastrulae, AmphiTcf expression begins in the mesendoderm. In neurulae, there is expression in the pharynx, hindgut, anterior notochord, somites, and at the anterior end of the neural plate. In early larvae, expression is detectable in the floor of the diencephalon, notochord, tail bud, forming somites, pharynx, and ciliated pit (a presumed homolog of the vertebrate adenohypophysis). Phylogenetic analysis of TCF/LEF proteins placed AmphiTcf as the sister group of a clade comprising vertebrate Tcf1, Lef1, Tcf3, and Tcf4. Comparison of developmental expression for amphioxus AmphiTcf and vertebrate TCF/LEF genes indicates that this gene family has undergone extensive subfunctionalization and neofunctionalization during vertebrate evolution.
T细胞因子（TCF）和淋巴样增强因子（LEF）基因编码的蛋白质是介导β-连环蛋白/ Wnt信号传导的转录因子。哺乳动物有四个这样的基因，而佛罗里达文昌鱼（佛罗里达文昌鱼）显然只有一个这样的基因（AmphiTcf）。从卵裂到原肠胚早期，该基因的细胞质母体转录本定位于动物极。在原肠胚中，AmphiTcf表达始于中内胚层。在神经胚中，在咽、后肠、前脊索、体节以及神经板的前端有表达。在早期幼虫中，可在间脑底部、脊索、尾芽、形成中的体节、咽和纤毛窝（推测为脊椎动物腺垂体的同源物）中检测到表达。对TCF/LEF蛋白的系统发育分析将AmphiTcf置于包含脊椎动物Tcf1、Lef1、Tcf3和Tcf4的进化枝的姐妹群中。文昌鱼AmphiTcf和脊椎动物TCF/LEF基因发育表达的比较表明，该基因家族在脊椎动物进化过程中经历了广泛的亚功能化和新功能化。
