UBA5介导Ufm1类泛素化修饰在遗传性共济失调发病机制中的作用研究

Hereditary ataxia (HA) is a group of clinical and genetic heterogeneous neurodegenerative disorders with high mortality and disability. In our previous work, we identified mutations in ubiquitin-like modifier activating enzyme 5 gene ( UBA5) in one Chinese pedigree presenting with autosomal recessive cerebellar ataxia. UBA5 is one of the ubiquitin-like activating enzyme family members, which is involved in the activation of ubiquitin-like modifier Ufm1. Recent studies have indicated that UBA5 mediating the Ufm1 modification pathway plays an important role in regulating cell proliferation and protecting the endoplasmic reticulum stress induced apoptosis. Our previous study demonstrated that UBA5 mutants had less stablility and reduced activity. We aim to further investigate the mechanism of UBA5 mediating the Ufm1 modification in the proliferation and apoptosis of cerebellar granule cells as well as the behavioral and pathological changes of the mice with UBA5 knockdown in cerebellum in order to provide some evidences for elucidating the pathogenesis of HA.

遗传性共济失调(Hereditary ataxia , HA)是一大类具有高度临床和遗传异质性、致死和致残率高的神经退行性疾病。前期工作中，我们应用全基因外显子组测序结合全基因组拷贝数变异分析，在一个常染色体隐性遗传性共济失调家系中克隆出致病基因UBA5。UBA5属于类泛素活化酶家族成员，参与类泛素分子Ufm1的活化。研究表明UBA5介导Ufm1类泛素化修饰通路在调控细胞的增殖过程和保护内质网应激诱导的细胞凋亡中发挥重要作用。我们前期的研究结果发现突变导致UBA5的稳定性和功能活性显著降低。本研究拟在前期工作基础上探讨UBA5介导Ufm1类泛素化修饰在小脑颗粒细胞增殖和凋亡中的作用机制以及小脑UBA5表达缺失小鼠的行为学及病理变化，从而为阐明遗传性共济失调发病机制提供依据。

遗传性共济失调(Hereditary ataxia , HA)是一大类具有高度临床和遗传异质性、致死和致残率高的神经退行性疾病。患者常在青中年起病，起病后逐渐丧失工作、生活能力，为家庭及社会带来沉重负担。其发病机制尚未明确，临床上缺乏有效治疗。本项目探讨UBA5介导Ufm1 类泛素化修饰在遗传性小脑性共济失调发病机制中的作用，有助于为阐明遗传性共济失调发病机制的研究提供新的依据。本研究利用免疫荧光技术、免疫印迹、RNAi技术及核质分离法初步证实UFM1/UBA5表达缺失对CDK5RAP3蛋白及其下游Cyclin D1的表达水平均无显著影响；采用TUNEL及免疫印迹法证实UBA5功能缺陷可导致小脑颗粒细胞在BFA应激诱导下凋亡水平增加，但具体机制仍需进一步探讨。此外，本研究发现SCA3-Tg(ATXN3-84.2)小鼠小脑内小胶质细胞及其介导的神经炎症反应显著激活，表明神经炎症反应可能参与SCA3-Tg(ATXN3-84.2)小鼠脑内神经细胞损伤及凋亡等过程。同时本研究发现UBA5功能缺陷对磷酸化AKT, P38, JNK相关通路均无显著影响，提示UBA5功能缺陷可能并未通过经典炎症通路参与遗传性共济失调的病理机制。本项目的研究结果为探索遗传性共济失调的发病机制提供了新的依据。