果蝇早老素基因的研究进展

果蝇早老素(Drosophila presenilin,DPS)是一种具有天冬氨酸水解酶活性的蛋白,在果蝇生长发育的各阶段都有表达,对果蝇的生长发育和调节胞内Ca2+平衡具有重要的作用。果蝇早老素功能的缺失能够导致Notch信号下降、神经元凋亡和胞质钙浓度上升,最终造成果蝇长时程记忆损伤和认识丧失。果蝇早老素的这些功能使之成为研究果蝇阿尔茨海默病(Alzheimer’s disease,AD)模型最重要的着手点之一,为阐明AD的病理提供了大量有价值的信息。文章概述了DPS基因与AD相关的功能。     

家族性阿尔茨海默病相关研究进展

阿尔茨海默病(Alzheimer’s disease,AD)是老年人中最常见的神经系统退行性疾病,给家庭和社会带来了十分沉重的负担。淀粉样蛋白级联反应假说是AD发病机制的重要学说之一,近年来备受关注。同时家族性老年痴呆(Familial Alzheimer’s Disease,FAD)在AD发病机制的研究中,起着至关重要的作用,其相关的FAD致病基因导致了AD的遗传性。本文将结合Aβ假说、产生过程和FAD的遗传因素进行讨论,浅析FAD的发病原因。     

Alzheimer氏病的遗传学研究进展

概述了目前已经确认的Alzheimer’sDisease（AD）的四个致病基因或相关基因,其中与早老性AD相关的有三个,分别是位于第21号染色体的app基因、第14号染色体的prisenilinⅠ基因和第1号染色体的prisenilinⅡ基因;与迟老性AD病相关的是位于第19号染色体的apoe基因。在早老性AD家族中发现了：（1）app基因的五个突变体;（2）编码跨膜蛋白的presenilinⅠ基因与线虫编码相同蛋白的sel-12基因有高度的同源性。apoe基因与AD发病有“剂量效应”。早老性AD中一种高效转基因鼠模型已被成功地建立。     

γ-分泌酶的重要组成部分PS

阿尔茨海默病(Alzheimer’s Disease,AD)与遗传因素密切相关。研究发现,大多数早发性家族性AD(FAD)和部分散发性AD(SAD)患者存在γ-分泌酶特别是早老素蛋白(presenilin,PS)基因突变。PS基因变异可引起β-淀粉样蛋白前体蛋白的加工和运输异常,产生过多的β-淀粉样蛋白(Aβ)而形成老年斑。对于SAD,PS表达的改变引起细胞骨架蛋白(如tau蛋白)之间的相互作用异常,而与神经纤维缠结(NFT)的形成有关。另外,PS使神经细胞对凋亡刺激的敏感性增强,以及PS基因突变产生过多的Aβ能引起脑内Bax表达增强,促进神经细胞的凋亡过程,引起AD脑内广泛的神经元减少或丢失。因此,PS在AD的发病中起到重要作用。     

早老素与阿尔茨海默病

早老素(presenilin,PS)与阿尔茨海默病(alzheimer’s disease,AD)密切相关,其基因突变是遗传性家族型AD的主要病因。PS可能作为γ分泌酶和(或)通过影响蛋白质的膜转运参与β淀粉样前体蛋白质(β-amyloid precur-sor protein,APP)代谢生成Aβ42的过程,而PS多蛋白质复合物的形成可能是其中的关键步骤,突变的PS则通过“获得功能”的方式引起Aβ42的产生和沉积增加。PS还可能通过影响未折叠蛋白质反应等多种途径来影响神经细胞对凋亡的敏感性。本综述旨在探讨PS在AD中的上述病理作用。     

γ-分泌酶抑制剂对LPS诱导的小胶质细胞分泌炎症因子的调控及机制

阿尔茨海默病(Alzheimer’s disease,AD)是一种进行性的脑内神经元退变性疾病,其中大多数与编码早老素的基因突变所导致的γ-分泌酶功能异常,小胶质细胞是阿尔茨海默病炎症反应中最主要的炎性细胞,实验以小鼠小胶质细胞系BV-2为研究对象,探究γ-分泌酶抑制后对细菌内毒素脂多糖(Lipopolysaccharides,LPS)诱导的炎症因子分泌的影响与分子机制。     

老年痴呆关联基因的研究进展

阿尔茨海默类痴呆（AD）是老年痴呆中最常见的一种,它以渐进性的神经功能退化并伴随着整体认知能力的下降为特征。早发性AD主要是由β-淀粉样前体蛋白（APP）基因和早老素基因突变引起,而与晚发性AD发病明显相关的只有载脂蛋白E-ε4 ( APOE-ε4)等位基因。但是APOE-ε4等位基因对AD发病既非充分又非必要,而且只能解释少于50%的AD的遗传变异。所以有必要进一步寻找与AD的关联基因。 Abstract:Dementia of the Alzheimer type (AD) is the leading cause of dementias for the elders.It is a progressively neurodegenerative disorder characterized by global cognitive decline.While most of the rare early-onset AD can be explained by mutations in APP gene and presenilin genes,the genetic etiology of the more common late-onset AD is only partly explained by the APOE-ε4 genotype.But the APOE-ε4 allele is neither necessary nor sufficient to cause disease and it can only account for less than one-half of the genetic variance of AD.Thus,more genes involved in AD are our special attention.     

内质网与阿尔采末病

内质网是调节蛋白质合成与运输,细胞应激反应和胞内钙水平的细胞器,阿尔采末病（Alzheimer‘s disease,AD)等神经疾病与内质网功能受损有关。内质网是生成β-淀粉样肽（Aβ1－42／43）的主要场所,早老素也位于内质网上,突变早老素影响了β－淀粉样肽前体蛋白（APP）加工并导致Aβ1－42／43生成增加,此过程与钙稳态失调有关,Aβ毒性与内质网上半胱天冬酶－12介导的内质网特异性凋亡途径有关,进一步研究内质网对阐明AD的发病机制很重要。     

治疗阿尔茨海默病的早老素/γ-分泌酶抑制剂和调节剂

阿尔茨海默病（Alzheimer’s disease,AD）又称老年痴呆症,是一种中枢神经系统（central nervous system,CNS）退行性疾病。β-淀粉样蛋白（β-amyloid,Aβ42）被认为在阿尔茨海默病（AD）的发生、发展过程中起核心作用。Aβ42由APP经β-和γ-分泌酶相继切割产生。γ-分泌酶是一个蛋白酶复合体,早老素（presenilin,PS）是γ-分泌酶的催化组分。因此,抑制PS/γ分泌酶的活性是治疗AD的关键,因而PS/γ分泌酶也是治疗AD的主要靶点。根据这些理论,人们提出了一些治疗AD的新方法,其中PS/γ-分泌酶抑制剂和调节剂成为近年来人们关注的焦点。     

抗T2DM药治疗阿尔茨海默病研究进展

阿尔茨海默病(Alzheimer’s disease,AD)的发病机制还不清楚,目前治疗或预防AD的方法效果有限。糖代谢减弱和胰岛素信号紊乱是AD与2型糖尿病(type 2 diabetes mellitus,T2DM)的共同特征,也是T2DM早发AD的主要机制。T2DM相关治疗药物能有效改善AD神经退行性病变,已引起广泛关注。本文总结抗T2DM药物治疗AD研究进展,为AD发病机制和药物研发提供思路。     

Genetic discoveries and advances in late-onset Alzheimer’s disease

Alzheimer’s disease (AD) is a heterogeneous disorder with multiple patterns of clinical manifestations. Recently, due to the advance of linkage studies, next-generation sequencing and genome-wide association studies, a large number of putative risk genes for AD have been identified using acquired genome mega data. The genetic association between three causal genes, including amyloid precursor protein, presenilin1, and presenilin2 in early-onset AD (EOAD), was discovered over the past few decades. These discoveries showed that there should be additional genetic risk factors for both EOAD and late-onset AD (LOAD) to help fully explain the leading molecular mechanisms in a single pathophysiological entity. This study reviews the clinical features and genetic etiology of LOAD and discusses a variety of AD-mediated genes that are involved in cholesterol and lipid metabolism, endocytosis, and immune response according to their mutations for more efficient selection of functional candidate genes for LOAD. New mechanisms and pathways have been identified as a result.     

Early-onset autosomal dominant Alzheimer disease: prevalence, genetic heterogeneity, and mutation spectrum.

To determine the prevalence of early-onset Alzheimer disease (EOAD) and of autosomal dominant forms of EOAD (ADEOAD), we performed a population-based study in the city of Rouen (426,710 residents). EOAD was defined as onset of disease at age <61 years, and ADEOAD was defined as the occurrence of at least three EOAD cases in three generations. Using these stringent criteria, we calculated that the EOAD and ADEOAD prevalences per 100,000 persons at risk were 41.2 and 5.3, respectively. We then performed a mutational analysis of the genes for amyloid precursor protein (APP), presenilin 1 (PSEN1), and presenilin 2 (PSEN2) in 34 families with ADEOAD ascertained in France. In 19 (56%) of these families, we identified 16 distinct PSEN1 missense mutations, including 4 (Thr147Ile, Trp165Cys, Leu173Trp, and Ser390Ile) not reported elsewhere. APP mutations, including a novel mutation located at codon 715, were identified in 5 (15%) of the families. In the 10 remaining ADEOAD families and in 9 additional autosomal dominant Alzheimer disease families that did not fulfill the strict criteria for ADEOAD, no PSEN1, PSEN2, or APP mutation was identified. These results show that (1) PSEN1 and APP mutations account for 71% of ADEOAD families and (2) nonpenetrance at age <61 years is probably infrequent for PSEN1 or APP mutations.     

Genetic markers for diagnosis and pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia in the elderly and represents an important and increasing clinical challenge in terms of diagnosis and treatment. Mutations in the genes encoding amyloid precursor protein (APP), presenilin 1 (PSEN1) and presenilin 2 (PSEN2) are responsible for early-onset autosomal dominant AD. The ε4 allele of the apolipoprotein E (APOE) gene has been recognized as a major genetic risk factor for the more common, complex, late-onset AD. Fibrillar deposits by phosphorylated tau are also a key pathological feature of AD. The retromer complex also has been reported to late-onset AD. More recently, genome-wide association studies (GWASs) identified putative novel candidate genes associated with late-onset AD. Lastly, several studies showed that circulating microRNAs (miRNAs) in the cerebrospinal fluid (CSF) and blood serum of AD patients can be used as biomarkers in AD diagnosis. This review addresses the advances and challenges in determining genetic and diagnostic markers for complex AD pathogenesis.     

The genetics of Alzheimer disease: back to the future

Three decades of genetic research in Alzheimer disease (AD) have substantially broadened our understanding of the pathogenetic mechanisms leading to neurodegeneration and dementia. Positional cloning led to the identification of rare, disease-causing mutations in APP, PSEN1, and PSEN2 causing early-onset familial AD, followed by the discovery of APOE as the single most important risk factor for late-onset AD. Recent genome-wide association approaches have delivered several additional AD susceptibility loci that are common in the general population, but exert only very small risk effects. As a result, a large proportion of the heritability of AD continues to remain unexplained by the currently known disease genes. It seems likely that much of this "missing heritability" may be accounted for by rare sequence variants, which, owing to recent advances in high-throughput sequencing technologies, can now be assessed in unprecedented detail.     

A population-based study of familial Alzheimer disease: linkage to chromosomes 14, 19, and 21.

Linkage of Alzheimer disease (AD) to DNA markers on chromosomes 14, 19, and 21 was studied in 10 families in which the disease was apparently inherited as an autosomal dominant trait. Families were derived from a Dutch population-based epidemiologic study of early-onset AD. Although in all probands the onset of AD was at or before age 65 years, the mean age at onset was after age 65 years in four families (referred to as "LOAD"). Among the six families with early-onset AD (referred to as "EOAD," i.e., mean age of onset of AD of relatives was at or before age 65 years), conclusive linkage to 14q24.3 was found in one family with a very early onset (around 47 years), while linkage to the same region was excluded in two other families. For the LOAD families, predominantly negative lod scores were obtained, and the overall lod score excluded linkage to chromosome 14. The results with markers on chromosome 19 and chromosome 21 were not conclusive for EOAD and LOAD. The findings of our study confirm genetic heterogeneity within familial EOAD.     

Mutations of presenilin genes in dilated cardiomyopathy and heart failure

Two common disorders of the elderly are heart failure and Alzheimer disease (AD). Heart failure usually results from dilated cardiomyopathy (DCM). DCM of unknown cause in families has recently been shown to result from genetic disease, highlighting newly discovered disease mechanisms. AD is the most frequent neurodegenerative disease of older Americans. Familial AD is caused most commonly by presenilin 1 (PSEN1) or presenilin 2 (PSEN2) mutations, a discovery that has greatly advanced the field. The presenilins are also expressed in the heart and are critical to cardiac development. We hypothesized that mutations in presenilins may also be associated with DCM and that their discovery could provide new insight into the pathogenesis of DCM and heart failure. A total of 315 index patients with DCM were evaluated for sequence variation in PSEN1 and PSEN2. Families positive for mutations underwent additional clinical, genetic, and functional studies. A novel PSEN1 missense mutation (Asp333Gly) was identified in one family, and a single PSEN2 missense mutation (Ser130Leu) was found in two other families. Both mutations segregated with DCM and heart failure. The PSEN1 mutation was associated with complete penetrance and progressive disease that resulted in the necessity of cardiac transplantation or in death. The PSEN2 mutation showed partial penetrance, milder disease, and a more favorable prognosis. Calcium signaling was altered in cultured skin fibroblasts from PSEN1 and PSEN2 mutation carriers. These data indicate that PSEN1 and PSEN2 mutations are associated with DCM and heart failure and implicate novel mechanisms of myocardial disease.     

Genetic study of familial cases of Alzheimer's disease

A small number (1-5%) of Alzheimer's disease (AD) cases associated with the early-onset form of the disease (EOAD) appears to be transmitted as a pure genetic, autosomal dominant trait. To date, three genes responsible for familial EOAD have been identified in the human genome: amyloid precursor protein (APP), presenilin 1 (PS1), and presenilin 2 (PS2). Mutations in these genes account for a significant fraction (18 to 50%) of familial cases of early onset AD. The mutations affect APP processing causing increased production of the toxic Abeta42 peptide. According to the "amyloid cascade hypothesis", aggregation of the Abeta42 peptide in brain is a primary event in AD pathogenesis. In our study of twenty AD patients with a positive family history of dementia, 15% (3 of 20) of the cases could be explained by coding sequence mutations in the PS1 gene. Although a frequency of PS1 mutations is less than 2% in the whole population of AD patients, their detection has a significant diagnostic value for both genetic counseling and treatment in families with AD.     

新疆维吾尔族、汉族阿尔茨海默病Neprilysin基因单核苷酸多态性研究

摘要目的：探讨新疆地区维吾尔族、汉族脑啡肽酶（Neprilysin,NEP）基因单核苷酸多态性与阿尔茨海默病（Alzheimer’SdiseaseAD）的关系。方法：对新疆地区维吾尔族、汉族≥50岁8284名人群进行AD流行病学调查,参照ADRDA．NINCDS的标准,选取散发性阿尔茨海默病（sporadicAlzheimer’s disease,SAD）患者209例（AD组）与正常对照220例（对照组）,应用聚合酶链反应一限制性片段长度多态性技术（PCR）检测NEP基因多态性,采用病例一对照的关联分析方法对NEP基因rs3736187位点进行基因型和等位基因频率分析。结果：（1）新疆维吾尔族、汉族两民族AD组与对照组间NEP基因基因型频率和等位基因频率分布差异均有统计学意义（P〈0．05）。携带T等位基因个体出现AD的危险性高于携带c等位基因的个体（0R=1．981,P〈0．05）。（2）新疆维吾尔族、汉族不同民族之间比较NEP基因基因型频率和等位基因频率分布差异均无统计学意义（P〉0．05）,而在同一民族中AD组和对照组之间比较NEP基因等位基因频率分布差异均具有统计学意义（P〈0．05）。（3）两个年龄分段（〈65岁及≥65岁）之间NEP基因基因型频率和等位基因频率分布差异均无统计学意义（P〉0．05）,而在同一年龄段内部AD组与对照组间等位基因频率分布差异具有统计学意义（P〈0．05）。（4）男性、女性之间NEP基因基因型频率和等位基因频率分布差异均无统计学意义,而在女性AD组与对照组间等位基因频率分布差异有统计学意义（P〈0．05）。结论：NEP基因rs3736187位点基因型频率和等位基因频率在新疆维吾尔族、汉族两民族间的分布相似;NEP基因的T等位基因是SAD的危险因素,在新疆维吾尔族、汉族两民族及女性SAD的发病中起重要作用。     

Molecular genetics of Alzheimer's disease: presenilin 1 gene analysis in a cohort of patients from the Poznań region

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by memory loss and personality changes. Pathological hallmarks of AD are: deposition of amyloid plaques and neurofibrillary tangles in the brain, accompanied by neuronal and synaptic loss. The genetic background of AD is heterogeneous and strongly depends on the form of the disease. In most of the families with early-onset AD (EOAD) (10% of the total population of patients), the disease segregates as an autosomal dominant fully penetrant trait. To date, some missense mutations in three genes encoding the amyloid precursor protein, presenilin 1 (PS1) and 2 (PS2) have been found to cause familial EOAD. We screened for mutations in the presenilin genes in a sample of 55 patients with familial or sporadic form of EOAD from the Poznan region. We found 4 missense mutations in the PS1 gene: A246E in exon 7, P267L in exon 8, E318G in exon 9, and L424R in exon 12 among 5 unrelated patients. The frequency of PS1 mutations was 11% (5 of 55) in the whole sample of the patients with EOAD or 50% (3 of 6) if the analysis was restricted to familial cases with a positive history of dementia in the patient's family.