ROLES OF TBX6 AND SPADETAIL IN THE ZEBRAFISH MESODERM

描述（改编自研究者摘要）：T-box基因编码一个家族 调节形态发生和分化的转录因子。的 研究人员提出了一种观察T-box基因功能的新方法， 对如何理解人类畸形的重大影响 T-box基因突变他们提出，T盒基因可以调节彼此的 表达和活性，并因此在一个细胞中T-box基因的组合表达， 细胞是决定其发育命运的关键。这一假设将 解释了T-box基因通常以重叠的方式表达的发现， 结构域和T-box基因通常似乎没有统一的功能， 整个表达域。为了验证这一假设，他们将研究 表达的三个斑马鱼T-box基因之间的相互作用 早期中胚层基因的表达最初是嵌套的：没有尾巴。 在整个中胚层前体群体中表达，尽管它 在背侧和腹侧中胚层有不同的功能。tbx 6和spadetail（spt） 在腹侧中胚层中表达。他们提出， tbx 6和spt在腹侧中胚层的作用是抑制 没有尾巴也能激活的背部特异性基因他们建议， T-box基因相互作用是因为它们编码的转录因子可以竞争 调节一些下游基因。目的#1测试基因相互作用 这三个基因之间。异位表达用于检测SPT是否能抑制 没有尾巴的背部功能。分离出TBX 6突变体， 分析了SPT和TBX 6;SPT双突变体。目标#2直接测试，使用 体外反式激活研究和胚胎中的报告转基因， 转录因子可以在确定的结合位点竞争调节 报告基因。目的#3使用差异杂交筛选来鉴定 内源性基因靶无尾，表达在一个结构域特异性 方式将分析靶基因的启动子区以确定靶基因的启动子区。 负责结构域特异性表达的顺式调节序列

DESCRIPTION (adapted from investigator's abstract): T-box genes encode a family of transcription factors that regulate morphogenesis and differentiation. The investigators present a new way to view T-box gene function that has significant implications for how to understand human malformations caused by T-box gene mutations. They propose that T-box genes can regulate each other's expression and activity, and hence the combined expression of T-box genes in a cell is crucial for determining its developmental fate. This hypothesis would account for the findings that T-box genes are often expressed in overlapping domains and that T-box genes often appear not to have a uniform function throughout their expression domain. To test this hypothesis, they will examine regulatory interactions between three zebrafish T-box genes expressed in the early mesoderm. Expression of the genes is initially nested: no tail is expressed throughout the mesoderm precursor population, although it has distinct functions in the dorsal and ventral mesoderm. tbx6 and spadetail (spt) are expressed within the ventral mesoderm. They propose that one function of tbx6 and spt in the ventral mesoderm is to suppress the expression of dorsal-specific genes that can be activated by no tail. They propose that the T-box genes interact because the transcription factors they encode can compete for regulation of some downstream genes. Aim #1 tests genetic interactions between the three genes. Ectopic expression is used to test if spt can suppress dorsal functions of no tail. tbx6 mutants are isolated and the effects of tbx6, spt, and tbx6;spt double mutants are analyzed. Aim #2 tests directly, using transactivation studies in vitro and reporter transgenes in embryos, whether the transcription factors can compete at defined binding sites for regulation of reporter genes. Aim #3 uses differential hybridization screening to identify endogenous gene targets of no tail that are expressed in a domain-specific manner. Promoter regions of target genes will be analyzed to determine the cis-regulatory sequences responsible for domain-specific expression