Nphp4 and Bbs5 are required for ciliary mediated cell signaling events that regulate cardiac development in the mouse

项目摘要：(最多30行) 初级纤毛是一种以微管为基础的结构，从几乎所有类型的细胞表面伸出。 哺乳动物的身体。纤毛的底部是形成过渡区(TZ)的蛋白质复合体， 将纤毛与细胞质隔开的扩散屏障。正确分离这些域对于以下方面非常重要 将纤毛建立为一个专门的感觉和信号间隔。蛋白质是如何运输到 而穿过TZ的纤毛外，人们对此知之甚少，但似乎涉及一个由8种蛋白质组成的复合体， 构成了BBSome。破坏这些结构的突变以及其他与初级纤毛相关的突变导致 人类的一系列疾病统称为纤毛病。这些破坏表现为过多的 高度可变的生理和发育障碍。我研究的主要目标是 阐明TZ和BBSome协同调节初级纤毛的机制 对小鼠正常心脏发育至关重要的功能，并阐明纤毛相关的调节 先天性心脏病(CHD)。在美国，先天性心脏病是导致出生缺陷的主要原因 婴儿的疾病和死亡。来自基因筛查的研究旨在识别已识别的CHD相关基因 61个CHD相关基因中有34个与纤毛相关。此外，有研究表明， 特别是从发育中的心脏切除了初级纤毛，报告了与CHD相关的异常。 这些数据有力地支持了这一应用的前提，即初级纤毛发挥了广泛的作用，而不是 目前尚不清楚其在冠心病发病机制中的作用。我们之前已经确定了已识别的遗传交互作用 通过对线虫的研究，发现TZ组分NPHP4和BBSome组分Bbs5之间的差异。这个 我的研究目标是将这些研究扩展到哺乳动物系统，并确定NPHP4对 和Bbs5在心脏发育过程中。我的初步数据显示NPHP4；Bbs5双突变小鼠 在胚胎16.5天到出生之间是胚胎致死的，而每个单一突变体都是活的。我的 初步研究表明，这种致命性很可能与扰乱心脏的危急事件有关 发展。根据我的初步数据，我假设NPHP4和Bbs5之间的遗传相互作用 是正常纤毛功能和心血管发育所必需的，可能是通过改变 蛋白质进出纤毛的运输。因此，这项研究产生的数据将提供关键的新 对初级纤毛如何调节心脏早期发育和纤毛功能障碍的理解 对冠心病有贡献。

Project Abstract: ( 30 lines maximum) The primary cilium is a microtubule-based structure that protrudes from the surface of nearly every cell type in the mammalian body. At the base of the cilium is a complex of proteins forming the transition zone (TZ), a diffusion barrier separating the cilium from the cytoplasm. Correct separation of these domains is important for establishing the cilium as a specialized sensory and signaling compartment. How proteins are transported into and out of the cilium across the TZ is poorly understood but appears to involve a complex of eight proteins that constitute the BBSome. Mutations disrupting these structures, and others related to primary cilia result in a spectrum of human diseases collectively called ciliopathies. These disruptions manifest in a plethora of physiological and developmental disorders that are highly variable. The primary goals of my study are to elucidate the mechanism by which the TZ and BBSome collaboratively work to regulate primary cilium functions important for normal cardiac development in mice, and to elucidate ciliary related regulation of Congenital Heart Defects (CHD). In the United States, CHD is the leading cause of birth-defect associated illness and death in infants. Studies from a genetic screen orchestrated to identify CHD-related genes identified 34 that were associated with the cilium out of 61 total CHD associated genes. Furthermore, studies that have specifically removed the primary cilium from the developing heart have reported CHD related abnormalities. These data strongly support the premise of this application that the primary cilium plays an extensive, but not yet understood, role in CHD pathogenesis. We have previously identified identified genetic interactions between the TZ component, Nphp4, and the BBSome component, Bbs5, through studies in C. elegans. The goal of my study is to extend these studies into a mammalian system and to define the contribution that Nphp4 and Bbs5 have during heart development. My preliminary data indicate that Nphp4; Bbs5 double mutant mice are embryonic lethal between embryonic day 16.5 and birth, while each of the single mutants is viable. My preliminary studies indicate that the lethality is likely associated with critical events disrupting cardiac development. Based on my preliminary data, I hypothesize that genetic interactions between Nphp4 and Bbs5 are necessary for proper cilia function and cardiovascular development, likely through altered regulation of transport of proteins into and out of the cilium. Thus, the data generated from this study will provide critical new understanding of how the primary cilium regulates early cardiac development and how cilia dysfunction contributes to CHD.