【摘要】：脊髓小腦性共濟失調(diào)(SCA, spinocerebellar ataxia)是一類遺傳性神經(jīng)退行性疾病,目前發(fā)現(xiàn)有30余種SCA亞型(DRPLA, SCA1-8,10-23,25-31)。多數(shù)SCA亞型由于致病基因內(nèi)CAG重復片段異常擴增,導致多聚谷氨酰胺鏈的突變蛋白在細胞核內(nèi)聚集形成核內(nèi)包涵體。SCA主要臨床特征表現(xiàn)為脊髓和小腦以及脊神經(jīng)、腦神經(jīng)、交感神經(jīng)等組織的病變。 合作單位通過全外顯子組測序在一個常染色體隱性遺傳的SCA家系中發(fā)現(xiàn)了新的致病基因X(由于文章尚未發(fā)表,該基因暫用X代替,之后M、A、B、C同)。X基因編碼的蛋白是近年新發(fā)現(xiàn)的類泛素化激活酶(E1),激活M基因編碼的類泛素蛋白。已發(fā)現(xiàn)的M的類泛素結(jié)合酶(E2)為A,類泛素連接酶(E3)為B以及已知的M作用底物C。在線蟲中的研究發(fā)現(xiàn)該類泛素化修飾系統(tǒng)參與線蟲生殖,發(fā)育以及對有害環(huán)境因素的抵抗力。在小鼠模型的相關(guān)研究中,X基因敲除小鼠胚胎致死。 目的：X基因在生物體中發(fā)揮的功能,以及X導致SCA的發(fā)病機制有待進一步被研究闡明。通過對X基因的果蠅模型進行研究,我們發(fā)現(xiàn)其能很好地模擬SCA疾病發(fā)生。 方法：利用果蠅UAS-GAL4系統(tǒng)誘導X基因以及M類泛素化修飾通路中其他重要分子的knockdown,觀察果蠅異常表型。 結(jié)果：1)全身表達GAL4誘導X基因的低表達能引起靜息時果蠅翅膀呈穩(wěn)定單翅或雙翅垂直展開的表型。25℃時Da-Gal4UAS-X RNAi雄果蠅表現(xiàn)率為33.5%,且該果蠅的飛行和爬行能力明顯降低,其壽命也明顯縮短；2)在X基因knockdown果蠅羽化后第三天,其胸部肌肉切片中未見肌肉組織形態(tài)和結(jié)構(gòu)的明顯異常；3)X基因knockdown的果蠅三齡幼蟲腹側(cè)縱向4號肌肉和13/12號肌肉上神經(jīng)肌肉接頭數(shù)目減少；4)全身性knockdown M和A基因,果蠅表現(xiàn)出與X基因knockdown相似表型,25℃時Da-Gal4UAS-M RNAi以及Da-Gal4UAS-A RNAi雄果蠅表現(xiàn)率分別為71.3%和37.8%。 結(jié)論：綜上所述,通過在果蠅模型中研究發(fā)現(xiàn)X基因knockdown很好地模擬SCA的發(fā)生。由于X基因參與M類泛素化修飾通路中的關(guān)鍵分子M和Aknockdown后能出現(xiàn)X基因knockdown后相似的果蠅表型,這些現(xiàn)象揭示該通路在SCA疾病發(fā)生中起到重要的作用。
[Abstract]:Spinal cerebellar ataxia (SCA, spinocerebellar ataxia) is a kind of hereditary neurodegenerative disease. More than 30 SCA subtypes (DRPLA, SCA1-8,10-23,25-31) have been found. Due to abnormal amplification of CAG repeats in most SCA subtypes, polyglutamine chain mutated proteins form intranuclear inclusions in the nucleus. The main clinical features of SCA subtypes are spinal cord, cerebellum, spinal nerve and cerebral nerve. A lesion of the sympathetic nerve, etc. A new pathogenic gene X was found in an autosomal recessive SCA family by sequencing the entire exon group. (because the article had not been published, the gene was temporarily replaced by X. The protein encoding the X gene is a newly discovered ubiquitin activator (E1), which activates the ubiquitin protein encoded by the M gene. The Ubiquitin binding enzyme (E _ 2) of M was found to be A, the ubiquitin ligase (E _ 3) was B and the known substrate of M was C _ (2). It was found that the ubiquitin modification system was involved in nematode reproduction, development and resistance to harmful environmental factors. The X gene knockout mouse embryos died in the related study of mouse model. Objective the function of the gene: X in organism and the pathogenesis of X-induced SCA need to be further studied. By studying the model of Drosophila, we found that X gene can simulate the occurrence of SCA disease well. Methods: the abnormal phenotype of Drosophila melanogaster was observed by knockdown, of X gene induced by UAS-GAL4 system and other important molecules in M class ubiquitin modification pathway. Results: the low expression of X gene induced by GAL4 expression in the whole body could induce the drosophila melanogaster to exhibit stable single-wing or double-wing vertical spread phenotype at 25 鈩，

本文編號：2225191