Role of T-box Genes in Mouse Development

该项目的长期目标是了解T-box转录因子基因家族的进化，确定它们在胚胎发育中的作用，并从发育机制的进化角度了解基因之间的相互关系。在前一次资助期间完成的工作中，我们在五个T-box基因中产生了有针对性的突变，所有这些基因都具有严重的发育后果，其中几个基因模拟了人类发育障碍。在这个提案中，我们关注Tbx2亚家族，Tbx2，Tbx3，Tbx4和Tbx5，因为它们在尿囊中表达，从进化的角度来看是一种新的结构，以及它们在四足类配对附肢的进化和发育中的潜在作用。我们将使用我们已经产生的突变等位基因、新的等位基因和等位基因的组合来研究功能冗余、独特的功能，以及这些基因是否相互作用。我们的突变分析已经显示了对尿囊和四肢发育的戏剧性影响，并且有明确的证据表明这个基因亚家族对人类健康的重要性。Tbx3和Tbx5的突变导致两种人类发育障碍，分别是尺骨-乳房和Holt-Oram综合征。我们将利用这组基因来推进我们的长期目标，即了解T-box家族成员之间的相互关系以及基因功能在这一组中是如何进化的。这些特定的目标不仅将阐明人类发育的基因控制，而且还将提供对基因家族内功能进化的洞察。具体目标1.产生Tbx5的多用途等位基因，以消除基因功能，允许实时表达报告，并提供可重定向的等位基因。特定目的2.产生Tbx4的条件等位基因，以研究发育后期的基因功能。具体目的3.研究Tbx亚家族基因Tbx2、Tbx3、Tbx4和Tbx5之间的调控和遗传相互作用。

The long-term objectives of this project are to understand the evolution of the T-box family of transcription factor genes, to determine their role in embryonic development., and to understand interrelationships between the genes in terms of the evolution of developmental mechanisms. In work completed during the previous funding period, we produced targeted mutations in five T-box genes, all of which have severe developmental consequences, and several which model human developmental disorders. In this proposal, we focus on the Tbx2 subfamily, Tbx2, Tbx3, Tbx4, and Tbx5 because of their expression in the allantois, a new structure in evolutionary terms, and their potential role in the evolution and development of paired appendages of tetrapods. We will use the mutant alleles we have already produced, new alleles, and combinations of alleles to study functional redundancy, unique function, and also whether the genes interact with one another. Our mutational analysis has already demonstrated dramatic affects on the development of the allantois and limbs and there is clear evidence of the importance of this gene sub- family to human health. Mutations in Tbx3 and Tbx5 cause two human developmental disorders, the ulnar-mammary, and Holt-Oram syndromes, respectively. We will use this group of genes to further our long-term objective of understanding interrelationships among T-box family members and how gene function evolved within this group. The Specific Aims will not only shed light on the genetic control of human development but also provide insight into the evolution of function within gene families. Specific Aim 1. Produce a multipurpose allele of Tbx5 to ablate gene function, allow real-time expression reporting and provide an allele that can be retargeted. Specific Aim 2. Produce a conditional allele of Tbx4 to study gene function late in development. Specific Aim 3. Investigate regulatory and genetic interactions between the genes of the Tbx subfamily, Tbx2, Tbx3, Tbx4, and Tbx5.