Transcriptional Control of Cardiac Conduction System Function by T-box Genes

描述(申请人提供)：尽管心脏传导系统(CCS)疾病具有重要的临床后果，但控制CCS功能的分子机制尚不清楚。这一建议结合了新的创新和最新的进展，从实验上剖析了心室传导系统(VCS)功能的转录控制，这是一个具有重大临床意义的问题。我们建立了一种新型的VCS特异性可诱导Cre转基因小鼠品系(MinKCreERT2)，并利用它从成熟的VCS(Tbx5MinK：CreERT2)中去除了Tbx5。在Tbx5MinK：CreERT2小鼠中，正常快速传导的VCS功能变慢，伴随着VCS基因表达的分子变化。重要的是，慢传导结节表型所需的Tbx3基因保持不变。这些观察结果和最近的文献结合在一起形成了一个总体假设：Tbx5/Tbx3 T盒编码决定了成熟的室性心脏传导系统的功能和分子局部表型。我们预测Tbx5决定了VCS的功能和分子同一性，并且Tbx3是VCS潜在的节点电位所必需的，在没有Tbx5的情况下被发现。我们建议(1)检验Tbx5促进VCS功能和分子表型的假说；(2)检验Tbx5直接调节VCS中SCN5A表达以控制VCS功能所需分子层次的假说；(3)检验Tbx3足以在VCS中建立节点表型的假说；以及(4)检验Tbx5和TBX3协同促进特化的CCS表型的假说。一组领先的CCS分子分析专家已经聚集在一起，研究成熟VCS功能的转录调控。一组全面的实验将确定Tbx5和Tbx3在CCS区域特异性的转录控制中的特定作用。这些研究将为未来详细描述CCS功能的转录网络建立一个平台，帮助临床CCS治疗和干预的知识开发。

DESCRIPTION (provided by applicant): Despite the significant clinical consequences of cardiac conduction system (CCS) disease, the molecular mechanisms that control CCS function are unknown. This proposal combines novel innovations with recent progress to experimentally dissect the transcriptional control of ventricular conduction system (VCS) function, a problem of great clinical significance. We have developed a novel VCS-specific inducible Cre transgenic mouse line (minKCreERT2) and utilized it to remove Tbx5 from the mature VCS (Tbx5MinK: CreERT2). The normally fast conducting VCS became functionally slow in Tbx5MinK:CreERT2 mice, with concomitant molecular alterations of VCS gene expression. Importantly, Tbx3, required for slow-conducting nodal phenotype was maintained. These observations and recent literature coalesce in the Overall Hypothesis: A Tbx5 / Tbx3 T-box code determines the functional and molecular regional phenotype of the mature Ventricular Cardiac Conduction System. We predict that Tbx5 determines VCS functional and molecular identity and that Tbx3 is required for underlying nodal potential of the VCS, uncovered in the absence of Tbx5. We propose to (1) Test the hypothesis that Tbx5 promotes functional and molecular VCS phenotype; (2) Test the hypothesis that Tbx5 directly regulates SCN5A expression in the VCS to control a molecular hierarchy required for VCS function; (3) Test the hypothesis that Tbx3 is sufficient for establishing a nodal phenotype in the VCS; and (4) Test the hypothesis that Tbx5 and Tbx3 cooperatively promote specialized CCS phenotype. A group of the leading experts in molecular analysis of the CCS have been assembled to investigate the transcriptional control of mature VCS function. A comprehensive experimental set will establish the specific roles of Tbx5 and Tbx3 in the transcriptional control of CCS regional specificity. These investigations will establish a platform for future efforts to detail transcriptional networks governing CCS function, aiding knowledgeable development of clinical CCS therapies and interventions.