Kawahara A, Wilm T, Solnica-Krezel L, Dawid I B
Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
Genesis. 2000 Oct;28(2):58-67. doi: 10.1002/1526-968x(200010)28:2<58::aid-gene30>3.0.co;2-n.
The gastrula organizer forms in the dorsal region of the zebrafish embryo, where the bozozok/dharma homeobox gene downregulates expression of the vega1 transcriptional repressor. Here, we describe a novel Vega family homeobox gene, vega2. Expression of vega2 is initiated at the ventral blastoderm margin during blastula stages, and by gastrulation becomes complementary to but partially overlapping with the dorsal expression domain of the homeobox gene goosecoid (gsc). This dorsal exclusion of vega2 expression is not observed in bozozok mutants in which organizer formation is impaired. Both vega2 and vega1 can physically interact with Gsc. Zebrafish embryos injected with vega2 mRNA failed to express gsc and developed a headless phenotype. Conversely, a putative dominant negative form of vega2, VP16-vega2, elicited the expansion of gsc expression and a dorsalized phenotype. We suggest that vega2, in cooperation with vega1, functions as a negative regulator of organizer genes including gsc, and participates in the refinement of the gastrula organizer domain.
原肠胚组织者在斑马鱼胚胎的背侧区域形成，在该区域，bozozok/dharma 同源框基因下调了vega1转录抑制因子的表达。在此，我们描述了一个新的Vega家族同源框基因——vega2。vega2的表达在囊胚期开始于腹侧胚盘边缘，到原肠胚形成期时，其表达与同源框基因goosecoid（gsc）的背侧表达域互补但部分重叠。在组织者形成受损的bozozok突变体中未观察到vega2表达的这种背侧排除现象。vega2和vega1均可与Gsc发生物理相互作用。注射vega2 mRNA的斑马鱼胚胎无法表达gsc，并发育出无头表型。相反，一种假定的vega2显性负性形式VP16-vega2引发了gsc表达的扩展和背化表型。我们认为，vega2与vega1协同作用，作为包括gsc在内的组织者基因的负调节因子，并参与原肠胚组织者区域的细化过程。
