ROLES OF TBX6 AND SPADETAIL IN THE ZEBRAFISH MESODERM

描述(摘自研究人员摘要)：T-box基因编码一个家族 调控形态发生和分化的转录因子。这个 研究人员提出了一种新的方法来观察T-box基因的功能 对如何理解人类畸形的重大意义 T-box基因突变。他们提出T-box基因可以相互调节 表达和活性，因此T-box基因的联合表达 细胞是决定其发育命运的关键。这一假设将 解释了T-box基因经常重叠表达的发现 结构域和T-box基因通常看起来并不具有统一的功能 在它们的表达域中。为了检验这一假设，他们将检验 3个斑马鱼T-box基因表达的调控相互作用 早期中胚层。基因的表达最初是嵌套的：没有尾巴 在整个中胚层前体种群中表达，尽管它有 背侧和腹侧中胚层有不同的功能。TBX6和SpaDetail(SPT) 均在腹侧中胚层表达。他们提出的一个功能是 TXX6和SPT在腹侧中胚层中的表达是抑制的 背部特有的基因，可以被没有尾巴激活。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 对一些下游基因进行调控。Aim#1测试遗传交互作用 在这三个基因之间。异位表达用于检验SPT是否能抑制 无尾的背部功能。分离了tbx6突变体，并观察了tbx6、 Spt、和tbx6；spt双突变体进行了分析。Aim#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上竞争进行调节 记者的基因。目标#3使用差异杂交筛选来识别 在特定区域中表达的内源性无尾基因靶点 举止。目标基因的启动子区域将被分析以确定 负责结构域特异性表达的顺式调控序列

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