胰泌素对小脑浦肯野神经元发育的调节作用及其相关机制的研究

Cerebellar Purkinje neurons play a critical role in motor coordination and motor learning abilities. The developmental disorders of Purkinje cells including neuron degeneration and dendritic abnormalities can cause cerebellar disorders, which are a group of diseases manifested with irreversible motor dysfunctions and lack effective treatment currently. Our previous studies have demonstrated the impaired motor coordination and motor learning ability as a result of Purkinje-specific deletion of secretin gene. The mechanism underlying such behavioral modulation, however, remained poorly understood. The research about secretin's potential developmental effects on Purkinje neuron is still lacked so far. In addition, secretin has been reported to facilitate neural development in various brain regions such as hippocampus other than the cerebellum. Based on these knowledge, we hypothesize that secretin can facilitate Purkinje neuron development. This project therefore aims to study the role of secretin in the development of cerebellar Purkinje neurons and related mechanisms, via the application of conditional secretin gene knockout mice. In brief, we will (1) study the role of secretin on the development of Purkinje cell; and (2) investigate the potential mechanism underlying secretin’s neural developmental functions. This study will help us to better understand the developmental paradigm of cerebellum, and provide theoretical grounds and novel drug targets for developing treatment against various cerebellar disorders.

小脑皮层Purkinje神经元对运动协调和运动学习能力起着重要作用，其发育障碍包括神经元退化和树突发育异常，可导致严重的小脑功能失调，表现为不可逆的进行性运动障碍，目前尚无有效临床治疗手段。我们既往研究已证实，胰泌素在Purkinje细胞中的特异性敲除会引起运动协调和运动学习能力的显著降低，但对这一运动调节的机制研究尤其是发育学相关领域尚属空白。其他学者此前曾报告胰泌素在其它脑区如海马体等具有一定的促神经生长作用。因此，我们假设胰泌素可促进Purkinje神经元发育的作用。本项目将运用条件式胰泌素基因敲除小鼠模型，着重探讨胰泌素对Purkinje神经元的发育调控作用及可能机制，包括：（1）阐明胰泌素对Purkinje细胞数量和树突形态发育的影响；（2）探索胰泌素调控发育的可能机制。本项目的成果将有助于更好了解小脑的神经发育机理，并为小脑退行性疾病的治疗提供理论依据和药物靶点。

本项目主要在前期发现小脑Purkinje内存在胰泌素富集表达，且胰泌素基因敲除可影响小鼠运动学习功能的基础上，进一步探索了胰泌素对小脑神经发育的可能调控机制。项目主要开了系列行为学、细胞发育学和分子生物学研究。首先通过Cre-Loxp技术构建了小脑Purkinje细胞特异性胰泌素基因敲除小鼠，通过行为学证据显示此种小鼠存在运动学习缺陷。随后采用EdU标记方法，在小鼠小脑皮层研究出生后早期细胞发育和迁移情况。结果发现胰泌素基因敲除小鼠的小脑颗粒细胞前体存在迁移发生的迟滞现象，并伴随有Purkinje细胞的群体形成和树突发育障碍。最后，我们通过在P0天小鼠的小脑内注射过表达胰泌素病毒的干预手段，成功增加了颗粒细胞前体的密度。上述结果提示了胰泌素可以调控小脑皮层出生后早期发育，从而影响小脑相关的运动学习功能。上述结果丰富了我们对于小脑发育调控机制的了解，并且为临床干预相关神经发育障碍或神经损伤提供了潜在的药物靶点。