Role of T-box Genes in Mouse Development

该项目的长期目标是了解T-box家族转录因子基因的进化，以确定它们在胚胎发育中的作用。并从发育机制的演变方面了解基因之间的相互关系。在上一个资助期完成的工作中，我们在五个T-box基因中产生了靶向突变，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。在这个建议中，我们专注于Tbx 2亚家族，Tbx 2，Tbx 3，Tbx 4和Tbx 5，因为它们在尿囊中的表达，在进化方面的新结构，以及它们在四足动物成对附属物的进化和发展中的潜在作用。我们将使用我们已经产生的突变等位基因、新等位基因和等位基因的组合来研究功能冗余、独特功能以及基因之间是否相互作用。我们的突变分析已经证明了对尿囊和四肢发育的巨大影响，并且有明确的证据表明该基因亚家族对人类健康的重要性。Tbx 3和Tbx 5的突变分别导致两种人类发育障碍，尺乳综合征和Holt-Oram综合征。我们将利用这组基因来进一步实现我们的长期目标，即了解T-box家族成员之间的相互关系以及基因功能如何在该组中进化。《特定目标》不仅将阐明人类发育的遗传控制，还将提供对基因家族内功能进化的深入了解。具体目标1。产生Tbx 5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以重新靶向的等位基因。具体目标2。产生Tbx 4的条件等位基因以研究发育后期的基因功能。具体目标3。研究Tbx亚家族，Tbx 2，Tbx 3，Tbx 4和Tbx 5基因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.