發(fā)布時(shí)間：2018-03-11 01:34

  本文選題：朊病毒基因　切入點(diǎn)：多態(tài)性　出處：《云南大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：朊病毒疾病,又名傳染性海綿狀腦病,是一類具有高度致死性和傳染性的神經(jīng)退行性疾病。該類疾病已在十幾種哺乳動(dòng)物中發(fā)現(xiàn),例如人類的克雅氏癥、羊的瘙癢病以及牛的瘋牛病等,給人類和動(dòng)物健康帶來(lái)了嚴(yán)重威脅,同時(shí)給社會(huì)經(jīng)濟(jì)造成了巨大損失,因此,對(duì)朊病毒疾病的研究已經(jīng)成為國(guó)內(nèi)外醫(yī)學(xué)和生物學(xué)領(lǐng)域研究的熱點(diǎn)。 朊病毒疾病的致病因子是朊蛋白(prion protein, PrP),它由朊病毒基因(prion protein gene, PRNP)編碼,在朊病毒疾病的致病機(jī)制中起到至關(guān)重要的作用。已有的研究證實(shí)包括人在內(nèi)的動(dòng)物對(duì)朊病毒疾病的易感性與PRNP基因的多態(tài)性相關(guān)。其中,與瘋牛病易感性相關(guān)的PRNP基因多態(tài)性包括以下四個(gè)方面：1)位于告PRNP基因啟動(dòng)子區(qū)域的23-bp插入/缺失(insertion/deletion,indel)多態(tài)；2)位于牛PRNP基因內(nèi)含子1的12-bp indel多態(tài)；3)牛PRNP基因編碼區(qū)的寡肽重復(fù)數(shù)目；4)牛PRNP基因編碼區(qū)的氨基酸多態(tài)性。令人注目的是,到目前為止全世界已有超過(guò)19萬(wàn)頭的黃牛被報(bào)道感染瘋牛病,盡管黃牛和水牛的系統(tǒng)發(fā)育關(guān)系很相近,但是沒(méi)有一頭水牛被報(bào)道感染瘋牛病(OIE統(tǒng)計(jì))。之前的研究都主要集中在對(duì)瘋牛病易感的黃牛上,而對(duì)瘋牛病不易感的水牛PRNP基因遺傳多樣性的研究甚少。 在本研究中,我們調(diào)查了涵蓋8個(gè)不同品種的312頭中國(guó)水牛的PRNP基因中四種多態(tài)的頻率分布情況,包括水牛PRNP基因23-bp indel多態(tài)、12-bp indel多態(tài)、開(kāi)放閱讀框中寡肽重復(fù)數(shù)多態(tài)以及編碼區(qū)的氨基酸多態(tài)。然后,匯集文獻(xiàn)中已經(jīng)報(bào)道過(guò)的所有患瘋牛病的黃牛、健康黃牛以及水牛群體的23-bp和12-bp indel多態(tài)的數(shù)據(jù)進(jìn)行全面地比較分析,我們的研究有三個(gè)重要的發(fā)現(xiàn)：1)在水牛PRNP基因23-bp和12-bp indel多態(tài)中,與瘋牛病易感性密切相關(guān)的缺失型等位基因(D23和D12)頻率非常低；2)水牛PRNP基因編碼區(qū)的6個(gè)寡肽重復(fù)的等位基因頻率顯著低于黃牛；3)水牛編碼區(qū)中有7個(gè)位點(diǎn)發(fā)生了非同義突變,且在兩個(gè)物種中的頻率分布有顯著差異：S4R、A16V、P54S、G108S、V123M、S154N和F257L,其中,S4R、A16V和V123M為種間固定突變位點(diǎn),水牛的54S、154N和257L三個(gè)位點(diǎn)的等位基因是固定的,而在黃牛中的頻率分布卻非常低。相反的,在黃牛中G108位點(diǎn)是固定的,而在93.1%的水牛中是絲氨酸,其余的是甘氨酸。 另外,基于PRNP編碼區(qū)的研究結(jié)果,以及在瘋牛病中PrP發(fā)生蛋白構(gòu)象轉(zhuǎn)換及傾向發(fā)生聚集這一分子特征,我們對(duì)野生型的黃牛PrP和水牛中含有的突變型PrP(S154N)進(jìn)行分子動(dòng)力學(xué)模擬分析,分析的結(jié)果表明突變能夠弱化聚集趨勢(shì)和構(gòu)象轉(zhuǎn)化的結(jié)論。因此,PrP分子動(dòng)力學(xué)模擬結(jié)果顯示黃牛比水牛更易于發(fā)生構(gòu)象轉(zhuǎn)變,這可能與黃牛易感染瘋牛病相關(guān)。這些研究結(jié)果表明牛PRNP基因的遺傳差異可能與物種對(duì)瘋牛病的易感性相關(guān)。我們的發(fā)現(xiàn)將有助于解釋這兩種關(guān)系相近的動(dòng)物對(duì)瘋牛病易感性的差異。
[Abstract]:Prion disease, also known as infectious spongiform encephalopathy, is a highly lethal and infectious neurodegenerative disease that has been found in more than a dozen mammals, such as Creutzfeldt-Jakob disease in humans. The pruritus of sheep and mad cow disease of cattle have brought serious threat to human and animal health, at the same time have caused huge losses to social economy, so, The research of prion disease has become a hot spot in the field of medicine and biology at home and abroad. The cause of prion disease is prion protein, PRPX, which is encoded by the prion gene prion protein genetics (PRNPN). Prion disease plays a crucial role in the pathogenesis of prion disease. Previous studies have shown that prion disease susceptibility in animals, including humans, is associated with polymorphism in the PRNP gene. The polymorphism of PRNP gene associated with susceptibility to mad cow disease includes the following four aspects: 1) 23-bp insertion / deletion in the promoter region of PRNP gene insertion / deletion in del2) 12-bp indel polymorphism in bovine PRNP gene intron 1) bovine PRNP gene coding region. Amino acid polymorphism in the coding region of bovine PRNP gene. More than 190,000 cattle around the world have been reported to be infected with mad cow disease so far, although the phylogenetic relationship between cattle and buffalo is very similar. However, no buffalo was reported to be infected with mad cow disease. Previous studies focused on cattle susceptible to mad cow disease, but few studies were conducted on the genetic diversity of PRNP gene in buffalo that was not susceptible to mad cow disease. In this study, we investigated the frequency distribution of four polymorphisms in the PRNP gene of 312 Chinese buffaloes covering 8 different breeds, including the 23-bp indel polymorphism of the PRNP gene of buffalo and 12-bp indel polymorphism. Oligoseptide repeat polymorphisms and amino acid polymorphisms in the coding region in the open reading box. Then, all the cattle with mad cow disease reported in the literature were collected. The data of 23-bp and 12-BP indel polymorphisms in healthy cattle and buffalo populations were compared and analyzed. Three important findings of our study were found in the PRNP gene 23-bp and 12-BP indel polymorphisms of buffalo. The frequency of deletion alleles (D23 and D12), which are closely related to the susceptibility of mad cow disease, is very low. The allele frequency of 6 oligoseptide repeats in the PRNP coding region of buffalo is significantly lower than that in the buffalo coding region, and there are 7 non-synonymous mutations in the coding region of buffalo. There were significant differences in the frequency distribution between the two species. There were significant differences in the frequency distribution between the two species. There were significant differences in the frequency distribution between the two species. Among them, S4RNA16V and V123M were the interspecific fixed mutation sites, and the alleles of 54Sn154N and 257L were fixed in buffalo, but the frequency distribution in yellow cattle was very low. The G108 locus was fixed in yellow cattle, serine in 93.1% buffalo and glycine in the rest. In addition, based on the results of PRNP coding region, and the molecular characteristics of protein conformation conversion and tendency of aggregation of PrP in mad cow disease, We simulated the molecular dynamics of wild type yellow cattle PrP and buffalo mutant PrPS154N. The results of analysis showed that the mutation could weaken the conformation transformation and the aggregation trend. Therefore, the results of PrP molecular dynamics simulation showed that yellow cattle were more prone to conformation transition than buffalo. These results suggest that genetic differences in bovine PRNP gene may be associated with the species susceptibility to mad cow disease. Our findings will help explain the relationship between the two closely related animals. The difference in susceptibility to mad cow disease.
【學(xué)位授予單位】：云南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：S852.653

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 Siqi Wang;Hui Zhao;Yaping Zhang;;Advances in research on Shadoo, shadow of prion protein[J];Chinese Science Bulletin;2014年09期

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本文編號(hào)：1596022