The Role of Primary Cilia in Murine Craniofacial Development

描述（由申请人提供）：初级纤毛是普遍存在的细胞器，其接收和传递来自细胞分子环境的分子信号。Kif3a是初级纤毛的延伸和功能所必需的鞭毛内转运蛋白。颅神经嵴细胞中Kif3a的条件性缺失导致严重的面中部扩张和舌头的缺失（无舌症）。这些表型，沿着我们的初步数据，表明Kif3a的缺失导致异常的Sonic hedgehog（Shh）活性。我们的目标是确定神经嵴细胞中Kif3a的缺失如何影响颅面复合体中的Shh信号。在我们的第一个目标中，我们将检验Kif3a的缺失阻止了神经嵴细胞中Gli3阻遏物的形成这一假设。 发展中的中面。我们将研究Kif3a在Gli3加工中所起的作用，并测试重新引入Gli3阻遏物是否可以挽救面中部表型。在我们的第二个目标中，我们测试了神经嵴细胞中Kif3a的缺失是否会破坏神经外胚层和面部外胚层中的Shh依赖性信号传导中心，这些信号传导中心对于中面的发育和生长是必要的。这一目的测试了Kif3a突变体中面中部表型是由二级非细胞自主机制引起的假设。在我们的第三个目标中，我们测试了这样的假设：Kif 3a的缺失会阻止发育中的舌头和下颌中Gli激活剂的形成。激活剂的损失随后导致Shh功能的损失。我们将比较Kif3a条件性基因敲除和另一种Shh依赖性失语模型之间的失语的分子机制。最后，我们将确定Kif3a突变体中舌的中胚层来源的肌肉前体细胞的命运。两者合计，这些研究将提供必要的洞察机制的初级纤毛功能在处理一个嘘信号内的发展颅面复合体。我们希望我们的研究将提供新的见解颅面纤毛病变的病因。

DESCRIPTION (provided by applicant): Primary cilia are ubiquitous organelles that receive and transduce molecular signals from the cell's molecular environment. Kif3a is an intraflagellar transport protein necessary for the extension and function of primary cilia. Conditional loss of Kif3a in cranial neural crest cells results in severe midfacial expansion and the loss of a tongue (aglossia). These phenotypes, along with our preliminary data, suggest that loss of Kif3a causes aberrant Sonic hedgehog (Shh) activity. Our objective is to determine how loss of Kif3a in neural crest cells affects Shh signaling within the craniofacial complex. In our first aim we will test th hypothesis that loss of Kif3a prevents the formation of the Gli3 repressor in neural crest cells of the developing midface. We will examine the role Kif3a plays in Gli3 processing and test if reintroduction of Gli3 repressor can rescue the midfacial phenotype. In our second aim we test if loss of Kif3a in neural crest cells disrupts Shh dependent signaling centers in neuroectoderm and facial ectoderm that are necessary for development and growth of the midface. This aim tests the hypothesis that the midfacial phenotype in Kif3a mutants is caused by a secondary, non-cell autonomous mechanism. In our third aim we test the hypothesis that loss of Kif3a prevents formation of Gli activator in the developing tongue and lower jaw. Loss of the activator subsequently leads to a loss-of-Shh function. We will compare the molecular mechanism of aglossia between Kif3a conditional knock-outs and another, Shh-dependent aglossia model. Finally, we will determine the fate of mesodermally derived muscle precursor cells of the tongue in Kif3a mutants. Taken together, these studies will lend essential insight into the mechanism of primary cilia function in processing a Shh signal within the developing craniofacial complex. We expect our studies will provide novel insight into the etiology of craniofacial ciliopathies.