Dissecting the Molecular Role of TBX1 in the Context of Human Pharyngeal Endoderm Development

项目总结 22q11.2缺失综合征(22q11.2DS)是最常见的微缺失综合征，由 22号染色体上0.7-3Mb的DNA半合子丢失，导致一系列临床表型。 核心表型起源于咽部器官发育受阻。受影响尤其严重 是第二心场依赖的心脏结构、大血管、甲状旁腺、胸腺和下层 头面部和面部肌肉。虽然大约50个基因可能被缺失，但这是单倍性的不足 转录因子Tbx1，它概括了与22q11.2DS相关的大部分关键表型。 小鼠的遗传学和发育研究已经证实，TBX1对小鼠的典型发育至关重要。 咽内胚层，胸腺、甲状旁腺发育所必需的暂时性解剖结构， 第四咽弓动脉。尽管有这种核心作用，但人们对分子的了解很少。 TBX1在咽内胚层发挥作用的机制。虽然有几项研究试图 为了研究TBX1在人类细胞中的作用，已经在其中进行过研究的细胞类型不能代表 在合适的发育阶段，以及在什么时候，TBX1发挥其关键作用。到目前为止，一项旨在整合 所有进入咽内胚层或第四咽弓动脉网络的关键基因都还没有尝试， 尤其是在人类细胞中。 R01利用了一种体外模型的最新发展，它忠实地模拟了细胞的形成和发展 人类咽部内胚层，从而提供了一个前所未有的机会来梳理出 Tbx1在其生理背景下。具体地说，该模型将用于识别转录靶标和 Tbx1(Aim1)的合作伙伴，研究Tbx1作为人类咽部内皮细胞表观遗传调节因子的作用 (AIM2)，并对新发现的TBX1基因座可能的调节区(Aim3)进行了机械研究。 最重要的假设是，TBX1处于基因调控网络的中心，对两者都至关重要 咽内胚层的形成和成熟及其周围中胚层的形态图案化 和神经脊细胞。 这项拟议的工作有望在TBX1单倍体不足的基础上确定分子机制和 确定可以通过药物干预挽救的途径。表观遗传学的剖析 负责咽内胚层形成的分子机制将有助于告知 22q11.2DS的细胞疗法的产生。

PROJECT SUMMARY 22q11.2 Deletion Syndrome (22q11.2DS), the most common of the microdeletion syndromes, is caused by hemizygous loss of 0.7-3 Mb of DNA on chromosome 22 and results in a constellation of clinical phenotypes. The core phenotype originates from disrupted development of the pharyngeal apparatus. Particularly affected are the second heart field-dependent heart structures, great vessels, parathyroids, thymus, and lower craniofacial and face muscles. Although approximately 50 genes may be deleted, it is the haploinsufficiency of the transcription factor TBX1 that recapitulates most of the critical phenotype associated with 22q11.2DS. Genetic and developmental mouse studies have established that TBX1 is critical for typical development of the pharyngeal endoderm, a transient anatomical structure necessary for development of the thymus, parathyroids, and 4th pharyngeal arch arteries. Despite this central role, very little is known regarding the molecular mechanisms by which TBX1 functions in the pharyngeal endoderm. While a handful of studies have attempted to study the role of TBX1 in human cells, the cell types they have been conducted in are not representative of the appropriate developmental stage where and when TBX1 plays its critical role. To date, an effort to integrate all the critical genes into a pharyngeal endoderm or 4th pharyngeal arch arteries network has not been attempted, particularly in human cells. This R01 leverages recent development of an in vitro model which faithfully mimics the formation and progression of human pharyngeal endoderm, thereby providing an unprecedented opportunity to tease out the functions of TBX1 in its physiological context. Specifically, this model will be used to identify the transcriptional targets and partners of TBX1 (Aim1), investigate the role of TBX1 as epigenetic regulator of the human pharyngeal endoderm (Aim2), and mechanistically investigate newly discovered putative regulatory regions of the TBX1 locus (Aim3). The overarching hypothesis is that TBX1 is at the center of a Gene Regulatory Network critical for both the formation and maturation of the pharyngeal endoderm and the morpho-patterning of the surrounding mesoderm and neural crest cells. The proposed work is expected to identify the molecular mechanism at the basis of TBX1 haploinsufficiency and identify pathways which could be rescued through pharmacological intervention. Dissection of the epigenetic and molecular machinery responsible for pharyngeal endoderm formation will be instrumental in informing the generation of cell therapies for 22q11.2DS.