Cardiac interaction networks as determinants of transcriptional specificity

摘要 先天畸形，或结构性出生缺陷，现在是#年婴儿死亡的主要原因。 美国和欧洲。在先天性畸形中，先天性心脏病(CHD)是最常见的 很普通。T-box转录因子TBX5的突变被发现是一种 人类心脏异常的范围，包括法洛四联症和Holt Oram综合征(HOS)， 与心脏间隔缺损相关的疾病状态。而TBX5是一个必不可少的 转录因子与心脏发育及其疾病的相关性已得到很好的证实，有 关于TBX5如何发挥作用的机制，有许多关键问题没有得到解答。我们不会 了解在心脏发育的不同阶段和心脏发育的不同阶段与TBX5复合的蛋白质是什么 动态平衡，这些相互作用如何调节Tbx5‘S对不同转录靶点的选择 不同的时间，或者这些相互作用如何作用于激活和/或抑制目标基因转录。 为此，我们的实验室最近启动了一种基于蛋白质组的定向方法来识别 与TBX5相关联的功能。这些研究表明，TBX5与转录的 核小体重塑和脱乙酰酶(NuRD)复合体的抑制机制。我们进一步 证明了TBX5人类疾病突变破坏了这种相互作用，导致异位 非心脏基因的表达通常受TBX5和室间隔缺陷的抑制 奥拉姆综合征。总而言之，这项工作导致了中心假设，即TBX5发挥作用，因此其 靶基因的组合在心脏发育过程中通过成分的变化来调节 Tbx5相互作用组。为了解决这一假设，我们将使用基于 确定Tbx5调节心脏中不同基因程序的机制的方法 通过定义内源性心脏TBX5转录复合体，建立其作用机制 TBX5的抑制和激活以及确定辅因子在TBX5中的潜在作用 转录调控。

ABSTRACT Congenital malformations, or structural birth defects, are now the leading cause of infant mortality in the US and Europe. Of the congenital malformations, congenital heart disease (CHD) is the most common. Mutations in the T-box transcription factor TBX5 have been found to be causative to a range of human cardiac abnormalities including Tetrology of Fallot and Holt Oram Syndrome (HOS), disease states associated associated with cardiac septal defects. While TBX5 is an essential transcription factor for heart development and its disease relevance is well established, there are many critical questions unanswered about the mechanism of how TBX5 functions. We do not understand what proteins complex with TBX5 during different stages of cardiac development and homeostasis, how these interactions regulate TBX5's choice of distinct transcriptional targets at different times, or how these interactions function to activate and/or repress target gene transcription. To this end, our labs recently initiated a directed proteomic-based approach to identify proteins that function in association with TBX5. These studies demonstrate TBX5 interacts with the transcriptional repression machinery of the Nucleosome Remodeling and Deacetylase (NuRD) complex. We further demonstrated that TBX5 human disease mutations disrupt this interaction, leading to ectopic expression of non-cardiac genes normally repressed by TBX5 and septal defects associated with Holt Oram syndrome. Collectively, this work led to the central hypothesis that TBX5 function and thus its suites of target genes are regulated during cardiac development through changes in the components of the TBX5 interactome. To address this hypothesis, we will used an integrated systems based approach to determine the mechanisms by which Tbx5 regulates distinct gene programs in the heart by defining the endogenous cardiac TBX5 transcriptional complexes, establish the mechanisms of TBX5 repression and activation and by determining the potential role of co-factors in TBX5 transcriptional regulation.