TUBB3及KIF21A基因新突变在轴突导向及发育过程中的作用机制研究

先天性颅神经异常支配疾病（CCDDs）是一组罕见的遗传相关颅神经肌肉疾病，临床表现为限制性眼球运动障碍，可伴有眼外多器官、系统异常。既往研究证实微管和驱动蛋白基因突变通过干扰颅神经元发育及轴突导向而致病。课题组前期对76个CCDDs家系进行了全基因组外显子测序，发现了微管蛋白TUBB3基因新突变S78T和驱动蛋白KIF21A基因新突变F355S，推测突变可能通过影响微管蛋白结构稳定性及动力学特性、破坏与驱动蛋白的相互作用而致病。接下来课题组拟在前期工作基础上，针对已经构建的突变小鼠敲入模型，进行行为学、外眼及颅脑MRI表型研究，对野生及突变型胚胎鼠的冰冻脑组织切片进行形态和颅神经发育分析、比较目标蛋白及其相互作用蛋白在靶器官的表达差异并检测突变对微管稳定性和动力学的影响。为明确维持微管动力学和稳定性的分子通路、揭示脑运动神经元发育和轴突导引的调控网络提供依据。

Congenital cranial dysinnervation disorders (CCDDs) are a group of rare heritable cranial neuromuscular disorders, which is characterized by restricted globe movement.And it can accompanied by extra-ocular multiple organs and systemic abnormalities. Previous studies have confirmed that mutations in genes encoding tubulin and kinesin can lead to disease by interfering with cranial neuronal development and axonal guidance. Our team had carried out the whole exom sequencing in 76 CCDDs families, and found two novel mutations S78T and F355S in TUBB3 and KIF21A gene respectively. We speculate that the mutations might cause disease by affecting the structural stability and dynamics of tubulin and/or destroying the interaction between tubulin and kinesin. Next, based on the previous work, we plan to study the behavior and phenotype of external eye and craniocerebral MRI in the mutant knock-in mouse model. And then, we would analyze the morphology and cranial nerve development of the frozen brain tissue sections of wild and mutant embryonic mice. Finally, we will compare the expression differences of target proteins and their interacting proteins in target organs, and detect the effect of mutations on microtubule stability and dynamics. It provides a basis for identifying the molecular pathways that maintain microtubule dynamics and stability, and for revealing the regulatory networks of brain motor neuronal development and axonal guidance.