【摘要】：甲基化CpG結(jié)合蛋白2(Methyl-CpG binding protein2, MECP2)是一種已知的轉(zhuǎn)錄抑制因子,帶有兩個(gè)特征性的功能域：甲基化DNA結(jié)合域和轉(zhuǎn)錄抑制結(jié)構(gòu)域,具有調(diào)節(jié)轉(zhuǎn)錄、改變?nèi)旧w構(gòu)象、參與RNA剪切等多種功能,在神經(jīng)發(fā)育過(guò)程中起著重要的作用。大量研究表明,MECP2基因突變與Rett綜合征、孤獨(dú)癥、智力低下等多種神經(jīng)發(fā)育性疾病相關(guān),現(xiàn)已成為研究疾病易感基因的基因型與人類(lèi)多種神經(jīng)發(fā)育性疾病之間關(guān)系的一個(gè)熱點(diǎn)。 藥物成癮已經(jīng)成為國(guó)內(nèi)外突出的社會(huì)和醫(yī)學(xué)問(wèn)題。長(zhǎng)期藥物成癮不僅損害患者身心健康,也會(huì)容易傳染艾滋病、誘發(fā)犯罪等,是嚴(yán)重的社會(huì)不穩(wěn)定因素。藥物成癮(drug addiction)是一種以失去自我控制、強(qiáng)迫性反復(fù)用藥為主要特征的慢性復(fù)發(fā)性腦疾病,它是遺傳因素和環(huán)境因素共同作用的結(jié)果。家系調(diào)查發(fā)現(xiàn),藥物依賴的遺傳率高達(dá)54%。人們對(duì)遺傳因素在藥物依賴中的作用關(guān)注度逐漸升高。近年來(lái),對(duì)藥物依賴的研究已取得了相當(dāng)大的進(jìn)展,但依賴的機(jī)制仍未完全闡明,不少治療方法雖起到一定的作用,但總體療效欠佳。只有徹底搞清成癮的生物學(xué)機(jī)制；才能找到有效的治療和預(yù)防方法。有研究表明MECP2基因與BDNF (Brain-derived neurotrophic factor)基因?yàn)樗幬镆蕾嚨囊赘谢?但現(xiàn)有的研究多數(shù)是生理學(xué)和形態(tài)學(xué)上的,而基因多態(tài)性與藥物依賴之間的關(guān)聯(lián)研究尚無(wú)報(bào)道。 本課題探討了MECP2基因和BDNF基因多態(tài)性與海洛因依賴的關(guān)聯(lián)性,以便于能夠更好的了解海洛因成癮的遺傳機(jī)制。對(duì)32名健康對(duì)照者的MECP2基因和BDNF基因進(jìn)行測(cè)序分析,找到SNP位點(diǎn)；在331名海洛因依賴者和325名健康對(duì)照者中,用SNaPshot技術(shù)進(jìn)行基因分型；根據(jù)調(diào)查量表信息將病例組中的男性患者分為高低劑量?jī)山M；用Haploview4.2及SPSS15.0軟件分析SNP與藥物依賴的相關(guān)性。結(jié)果發(fā)現(xiàn)MECP2基因rs2075597、rs61751363和rs189253298的基因型及等位基因頻率在海洛因依賴組與對(duì)照組中分布差異不顯著,而rs189253298基因型頻率在低劑量組和高劑量組中的分布差異顯著,有統(tǒng)計(jì)學(xué)意義(P=0.012)。這表明MECP2基因的rs189253298多態(tài)性位點(diǎn)與海洛因依賴者成癮后每天海洛因的使用量相關(guān),攜帶有G等位基因的個(gè)體每天使用的海洛因量較低,是一個(gè)保護(hù)因素。BDNF基因的rs11030102的等位基因頻率在海洛因依賴組與對(duì)照組中分布差異顯著,有統(tǒng)計(jì)學(xué)意義(P0.05)。rs11030101和rs7124442基因型頻率在低劑量組和高劑量組中的分布差異顯著(P=0.033,P=0.032)。表明BDNF基因的rs11030102多態(tài)性位點(diǎn)與海洛因依賴相關(guān),rs11030101和rs7124442多態(tài)性位點(diǎn)與海洛因依賴者成癮后每天海洛因的使用量相關(guān),攜帶有T、G等位基因的個(gè)體每天使用的海洛因量較低,是一個(gè)保護(hù)因素。 孤獨(dú)癥一般起病于嬰幼兒時(shí)期,是一種以語(yǔ)言障礙、社交障礙和刻板狹隘的興趣為基本臨床特征的廣泛性發(fā)育障礙(Pervasive developmental disorder,PDD),常常合并精神發(fā)育遲滯、感知覺(jué)和情緒等方面異常。嚴(yán)重影響兒童身心發(fā)展。目前認(rèn)為它是由遺傳、神經(jīng)生化、病毒感染、免疫系統(tǒng)等多種因素所引起的,其中遺傳因素在孤獨(dú)癥的發(fā)病中占有重要的地位。近年來(lái)的流行病學(xué)研究發(fā)現(xiàn)孤獨(dú)癥的患者數(shù)正逐年增加。一般孤獨(dú)癥的男性患者多于女性患者,二者的比例接近4：1,這表明孤獨(dú)癥的發(fā)病原因可能與X染色體相關(guān),另外孤獨(dú)癥和Rett綜合征均屬于廣泛性發(fā)育障礙(PDD),二者的許多臨床表現(xiàn)比較相似。據(jù)此人們推測(cè)孤獨(dú)癥與RTT可能具有某些共同的發(fā)病機(jī)制。而MECP2基因是目前RTT已經(jīng)確認(rèn)的主要致病基因,于是MECP2基因的突變?cè)诠陋?dú)癥中的作用成為研究的熱點(diǎn)。本課題在288個(gè)孤獨(dú)癥患者與384個(gè)正常對(duì)照者樣本中對(duì)MECP2基因進(jìn)行測(cè)序,發(fā)現(xiàn)了5個(gè)錯(cuò)義突變(T197M、G232A、H371R、E394K、G428S),對(duì)其進(jìn)行功能研究發(fā)現(xiàn),這五個(gè)突變并不影響MECP2蛋白的正確定位,而Real-Time PCR的結(jié)果表明T197M、G232A是比較嚴(yán)重的轉(zhuǎn)錄抑制功能突變,而另外三個(gè)并不是完全的轉(zhuǎn)錄抑制突變,可能與其他功能有關(guān)。另外我們還在288個(gè)孤獨(dú)癥患者中檢測(cè)了MECP2基因拷貝數(shù)的變異,在兩個(gè)孤獨(dú)癥患者中檢測(cè)到MECP2基因存在一個(gè)拷貝數(shù)的缺失。這表明MECP2基因的突變與孤獨(dú)癥之間存在一定的關(guān)聯(lián)性。
[Abstract]:Methyl-CpG binding protein 2 (MECP2) is a known transcription inhibitor with two characteristic functional domains: methylated DNA binding domain and transcription inhibitory domain. It plays an important role in neural development by regulating transcription, altering chromosomal conformation, and participating in RNA splicing. A large number of studies have shown that MECP2 gene mutations are associated with Rett syndrome, autism, mental retardation and other neurodevelopmental disorders, and have become a hot spot in the study of the relationship between the genotypes of disease susceptibility genes and various human neurodevelopmental diseases.
Drug addiction has become a prominent social and medical problem both at home and abroad. Long-term drug addiction is not only harmful to the physical and mental health of patients, but also susceptible to infection of AIDS, crime and so on. It is a serious social instability factor. Drug addiction is a chronic relapse characterized by loss of self-control and compulsive repeated use of drugs. Family studies have found that the heritability of drug dependence is as high as 54%. Attention to the role of genetic factors in drug dependence has gradually increased. In recent years, considerable progress has been made in the study of drug dependence, but the mechanism of dependence has not been fully elucidated. Fewer treatments play a role, but the overall effect is poor. Only by thoroughly understanding the biological mechanism of addiction can effective treatment and prevention be found. Some studies have shown that MECP2 gene and BDNF (Brain-derived neurotrophic factor) gene are susceptible genes for drug dependence, but most of the existing studies are physiological and morphological. In fact, the association between genetic polymorphism and drug dependence has not been reported.
In order to better understand the genetic mechanism of heroin addiction, the association between the polymorphisms of MECP2 and BDNF genes and heroin dependence was explored. The SNP loci of MECP2 and BDNF genes were sequenced and analyzed in 32 healthy controls, and the SNaPshot technique was used in 331 heroin addicts and 325 healthy controls. The results showed that the genotype and allele frequencies of MECP2 gene rs2075597, rs61751363 and rs189253298 were found in heroin dependent group and control group. The results showed that the rs189253298 polymorphism of MECP2 gene was associated with daily heroin use in heroin addicts, and the individuals with G allele used the sea every day. The allele frequencies of BDNF gene rs11030102 were significantly different between heroin addicts and controls (P 0.05). The genotype frequencies of rs11030101 and rs7124442 were significantly different between low dose group and high dose group (P = 0.033, P = 0.032). The rs11030101 and rs7124442 polymorphisms were associated with daily heroin use in heroin addicts. Individuals with T and G alleles had lower daily heroin use, which was a protective factor.
Autism, which usually begins in infancy, is a pervasive developmental disorder (PDD) characterized by language disorders, social disorders and stereotyped narrow interests. It is often associated with mental retardation, sensory and emotional abnormalities. It seriously affects the physical and mental development of children. Genetic factors play an important role in the pathogenesis of autism. Epidemiological studies in recent years have found that the number of autistic patients is increasing year by year. The etiology of autism may be related to X chromosome. In addition, both autism and Rett syndrome belong to generalized developmental disorder (PDD), and many of their clinical manifestations are similar. The role of P2 gene mutation in autism has become a hot topic of research. In this study, five missense mutations (T197M, G232A, H371R, E394K, G428S) were found in 288 autistic patients and 384 normal controls. The functional studies showed that these five mutations did not affect the correct localization of MECP2 protein. The results of Real-Time PCR showed that T197M and G232A were severe transcriptional inhibition mutations, while the other three were not complete transcriptional inhibition mutations, which may be related to other functions. A deletion of copy number indicates that there is a certain correlation between the mutation of MECP2 gene and autism.
【學(xué)位授予單位】：陜西師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2012
【分類(lèi)號(hào)】：R749.61

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

1 孔靜思;王亭芳;鄭麗娜;左秋紅;;孤獨(dú)癥的研究進(jìn)展[J];生物學(xué)教學(xué);2010年11期

2 劉可智;梁雪梅;郭蘭婷;;兒童孤獨(dú)癥的遺傳學(xué)研究進(jìn)展[J];實(shí)用兒科臨床雜志;2010年23期

，

本文編號(hào)：2238356