Role of the Ciliary Protein C2CD3 in Mandibular Skelotogenesis

项目摘要/摘要 初级纤毛是非运动性的、以微管为基础的细胞器，从细胞膜突出到感觉。 调节细胞的外部环境，协调多条信号通路的转导。中途中断 初级纤毛的结构或功能导致一类被称为纤毛病的疾病。骨骼通常是 受纤毛疾病影响作为纤毛疾病的患者通常表现为骨软骨发育不良(OCDPs)- 骨和软骨--如小颌畸形和下颌畸形。口腔-面部-数字综合征是一种 伴有多个OCDP的纤毛病变的子集。有相当大的表型重叠 口腔-面部-指端综合征和其他骨骼纤毛疾病的亚型，使它们难以正确地 相互诊断和区别对待。纤毛疾病的表型重叠程度相当高， 影响骨骼，再加上缺乏治疗纤毛病态OCDPS的方法，这使这成为一个重要的问题 生物医学方面的问题。这项拟议的工作重点是了解睫状蛋白C2cd3的需求 在利用禽类C2cd3突变体talpid2(Ta2)和 条件C2cd3fl/fl小鼠。C2cd3定位于初生纤毛的远端中心粒，是 纤毛发生。C2cd3基因突变导致人类14型口腔-面部-指端纤毛病综合征 初步数据表明，talpid2胚胎存在大量的下颌OCDP，如双侧 Meckel的软骨发育不良和发育不良的骨骼元素。目前还没有进行深入的研究 这些表型出现了。在目标1中，我将确定双侧Meckel‘s软骨发育不良是否为外生骨软骨病- 软骨帽骨肿瘤，定义为缺乏细胞极性和纤毛伸展，Ext1/2减少 表达，并减少硫酸乙酰肝素的合成。TA2胚胎中FGF8的表达也增加 发育中的下颌骨，但目前尚不清楚这是否会导致下颌骨发育不良。对于目标2，我会 确定扩展的下颌FGF8信号是否足以诱导TA2下颌骨发育不全 珠子植入发育中的鸟类下颌骨。最后，C2cd3在整个 发育中的胚胎，尚不清楚头面部上皮或间充质中C2cd3的缺失是否会导致 下颌骨OCDP。对于目标3，我将用DHand-Cre和Crect小鼠有条件地培育C2cd3fl/fl小鼠 删除下颌间充质和上皮中的C2cd3，以确定C2cd3在这两种组织类型中是否丢失 结果导致下颌骨OCDP。这项研究对于促进我们对细胞和 纤毛病变患者下颌骨OCDPs的分子病因学研究更好地理解发展中的 下颌OCDPs在纤毛疾病中的机制对于进一步完善诊断和发展是必要的 侵入性较小的治疗方案。

Project Summary/Abstract Primary cilia are non-motile, microtubule-based organelles that protrude from the cellular membrane to sense the cell’s external environment and to coordinate the transduction of multiple signaling pathways. Disruptions in the structure or function of primary cilia result in a class of disorders known as ciliopathies. The skeleton is often affected in ciliopathies as ciliopathy patients often present with osteochondrodysplasias (OCDPs) - anomalies of bone and cartilage - such as micrognathia and mandibular dysmorphology. Oral-facial-digital syndromes are a subset of ciliopathies that present with several OCDPs. There is considerable phenotypic overlap between subtypes of oral-facial-digital syndromes and among other skeletal ciliopathies, making them difficult to properly diagnose and differentiate from each other. The substantial degree of phenotypic overlap of ciliopathies that affect the skeleton combined with the lack of a cure for ciliopathic OCDPs make this an issue of significant biomedical concern. This proposed work focuses on understanding the requirement of the ciliary protein C2cd3 during the development of the mandibular skeleton by utilizing the avian C2CD3 mutant talpid2 (ta2) and the conditional C2cd3fl/fl mouse. C2cd3 localizes to the distal centrioles of primary cilia and is required for ciliogenesis. Mutations in C2cd3 result in the human ciliopathy Oral-facial-digital syndrome subtype 14. My preliminary data indicates that talpid2 embryos present with numerous mandibular OCDPs, such as bilateral Meckel’s chondrodysplasias and hypoplastic skeletal elements. There has yet to be an in-depth study as to how these phenotypes arise. In Aim 1, I will determine if the bilateral Meckel’s chondrodysplasias are exostoses - cartilage-capped bony tumors defined by lack of cellular polarity and ciliary extension, reduced Ext1/2 expression, and reduced heparan sulfate synthesis. ta2 embryos also possess increased FGF8 expression in the developing mandible, but it is not known if this leads to mandibular bone hypoplasia. For Aim 2, I will determine if expanded mandibular FGF8 signaling is sufficient to induce ta2 mandibular skeletal hypoplasia using bead implantations in the developing avian mandible. Lastly, C2cd3 is expressed ubiquitously throughout the developing embryo and it is not known if loss of C2cd3 in the craniofacial epithelium or mesenchyme leads to mandibular OCDP. For Aim 3, I will breed C2cd3fl/fl mice with the dHAND-Cre and Crect mice to conditionally delete C2cd3 in the mandibular mesenchyme and epithelium to determine if C2cd3 loss in either tissue type results in mandibular OCDP. This study is important for advancing our understanding of the cellular and molecular etiology of mandibular OCDPs in ciliopathic patients. A greater understanding of the developmental mechanisms of mandibular OCDPs in ciliopathies is necessary for further refined diagnosis and the development of less invasive therapeutic options.