Role and Regulation of Cellular Polarity in Craniofacial Skeletogenesis

项目摘要 一个有功能的骨骼系统依赖于软骨和骨骼的协调发展 胚胎发生。然而，人们对控制细胞和分子机制知之甚少。 软骨的极化生长，决定了软骨内骨的大小和形状。解开 引导间充质细胞凝聚并排列成软骨形成前堆叠的信号是 了解塑造骨骼组织和成长的早期事件。澄清这些问题 这一过程将使骨骼畸形和出生缺陷得到更好的诊断和治疗。 此外，控制软骨形态发生和分化的分子可能是相当重要的。 提高先天性出生缺陷诊断和治疗水平的临床意义 开发以间充质干细胞为基础的骨骼疾病治疗方法。我们最近的发现是 平面细胞极性通路对于软骨细胞正确堆积是必不可少的，先前的一项研究表明 长骨软骨生长板和生长带图案化的未知机制 在头盖骨中。我们实验室的戏剧性结果现在证明刺猬的信号， 以其在长骨生长板中的关键作用而闻名，也调节斑马鱼的软骨极性。 Hedgehog信号缺陷的胚胎表现为软骨堆积缺陷。此外，还将两种方法进行比较 进化出截然不同的头面部的非洲慈鱼的软骨生长区 骨骼形状，表明幼虫发育过程中生长区大小的差异与这些 特定于物种的形状。目标1将在我们之前资助的工作的基础上解决这一假设 Hedgehog信号通过平面细胞极性调节生长区模式。软骨表型 将在已操纵Hedgehog信号的胚胎和幼虫中进行评估 药理上的或遗传上的。我们也将确定刺猬调控的极性通路。 作为信号和反应细胞。目标2将解决生长带中极性的作用， 包括繁殖方式，对刺猬的反应，以及在软骨膜中的作用。为了这个 我们有了新的转基因技术，我们可以用来追踪极性，以及针对软骨膜的方法 细胞。最后，目标3将专注于实验室中的一个新的“EVO-DEVO”项目，发现与 用定量性状基因座定位技术研究文昌鱼软骨的极性和生长区。加在一起，这些 研究将导致对相对未被探索的细胞极性功能的机械性洞察 脊椎动物骨架的软骨内骨。这项工作将导致对人类原因的洞察 Hedgehog信号的骨骼障碍，如短指，以及极性障碍，如 Robinow和Van Maldergem综合征。

Project Summary A functional skeletal system depends on the coordinated development of cartilages and bones during embryogenesis. However, little is known about the cellular and molecular mechanisms that control the polarized growth of cartilages, which determine endochondral bone size and shape. Unraveling the signals that direct mesenchymal cells to condense and align into pre-chondrogenic stacks is key to understanding early events that shape the organization and growth of the skeleton. Elucidating these processes will allow better diagnosis and treatments for skeletal malformations and birth defects. Moreover, molecules that control cartilage morphogenesis and differentiation may be of considerable clinical importance both for improvements in diagnosing and treating congenital birth defects as well as developing mesenchymal stem cell based therapies for skeletal disorders. Our recent finding that planar cell polarity pathways are essential for cartilage cells to stack properly, suggests a previously unappreciated mechanism for patterning cartilage growth plates of long bones as well as growth zones in bones of the skull. Dramatic results from our laboratory now demonstrate that Hedgehog signaling, well known for its critical roles in long bone growth plates, also regulates cartilage polarity in zebrafish. Embryos deficient in Hedgehog signaling show defects in cartilage stacking. Moreover, comparisons of cartilage growth zones in African cichlid fishes that have evolved dramatically different craniofacial bone shapes, reveal that growth zone size differences during larval development correlate with these species-specific shapes. Aim 1 will build upon our previously funded work to address the hypothesis that Hedgehog signaling regulates growth zone patterning via planar cell polarity. Cartilage phenotypes will be evaluated in embryos and larvae in which Hedgehog signaling has been manipulated pharmacologically or genetically. We will identify the polarity pathways regulated by Hedgehog as well as the signaling and responding cells. Aim 2 will address the functions of polarity in growth zones, including modes of propagation, responsiveness to Hedgehog, and roles in the perichondrium. For this we have new transgenics with which we can track polarity, and methods for targeting perichondrial cells. Finally, Aim 3 will focus on a new “evo-devo” project in the lab, discovering new genes involved in cartilage polarity and growth zones using quantitative trait locus mapping in cichlids. Together, these studies will lead to mechanistic insights into the relatively unexplored functions of cellular polarity in endochondral bones of the vertebrate skeleton. This work will lead to insights into the causes of human skeletal disorders of Hedgehog signaling, such as brachydactyly, as well as polarity disorders such as Robinow and Van Maldergem syndromes.