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

描述（由申请人提供）：尽管心脏传导系统（CCS）疾病具有显著的临床后果，但控制CCS功能的分子机制尚不清楚。本研究结合近年来的研究进展，对脑室传导系统（VCS）功能的转录调控进行实验研究，这是一个具有重要临床意义的问题。我们开发了一种新的VCS特异性诱导Cre转基因小鼠系（minKCreERT2），并利用它从成熟VCS （Tbx5MinK: CreERT2）中去除Tbx5。正常快速传导的VCS在Tbx5MinK:CreERT2小鼠中变得功能缓慢，并伴有VCS基因表达的分子改变。重要的是，慢传导节点表型所需的Tbx3得以维持。这些观察结果和最近的文献在总体假设中结合在一起：Tbx5 / Tbx3 T-box编码决定了成熟心室心脏传导系统的功能和分子区域表型。我们预测Tbx5决定了VCS的功能和分子特性，并且Tbx3是VCS潜在节点电位所必需的，在Tbx5缺失的情况下被发现。我们提出(1)验证Tbx5促进VCS功能和分子表型的假设；(2)验证Tbx5直接调控VCS中SCN5A的表达以控制VCS功能所需的分子层次结构的假设；(3)验证Tbx3足以在VCS中建立节点表型的假设；(4)验证Tbx5和Tbx3共同促进CCS特化表型的假说。一组领先的专家在分子分析CCS已经组装研究成熟VCS功能的转录控制。一套全面的实验将确定Tbx5和Tbx3在CCS区域特异性转录控制中的具体作用。这些研究将为未来详细研究控制CCS功能的转录网络建立一个平台，帮助临床CCS治疗和干预的知识发展。

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.