共查询到17条相似文献,搜索用时 78 毫秒
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摘要:微生物未甲基化CpG DNA为富含未甲基化胞嘧啶-鸟嘌呤二核苷酸的DNA片段,能够被动物肠道细胞Toll样受体家族中的TLR9 受体(Toll-like receptor 9,TLR9)特异性识别。未甲基化CpG DNA作为一种动物肠道免疫刺激因子,不仅能够直接调节肠道固有免疫应答,同时还能间接介导肠道适应性免疫应答。未甲基化CpG DNA具有调节机体免疫应答作用的应用前景,成为免疫佐剂开发的研究热点。本文主要综述微生物未甲基化CpG DNA基本概念、受体TLR9的特征、调节动物肠道免疫作用及其信号机制,同时阐述了未甲基化CpG DNA作为免疫佐剂在实际中的应用,最后对微生物未甲基化CpG DNA研究与开发利用前景进行了展望。 相似文献
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CpG DNA:一种新型免疫佐剂 总被引:3,自引:0,他引:3
美国依阿华大学医学院Krieg[1]等报道,一种含有胞嘧啶鸟嘌呤二核苷酸(CpG)的DNA片段是一种强烈的非特异性免疫刺激剂。这种CpGDNA可作用于多种免疫细胞。用含CpG序列的细菌DNA可诱导小鼠95%的B细胞进入细胞增殖周期并分泌IgM、IL-... 相似文献
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CpGmotif是以CpG二核苷酸为核心的,未甲基化的特殊的DNA序列,在微生物基因组中的出现频率高于在脊椎动物中的出现频率,近年来发现这种特殊的基序具有许多免疫调节作用。如刺激淋巴细胞增殖,分泌细胞因子,产生IgG2a类抗体,诱导Th1类应答,本介绍这种独特的CpGmotif的特征,可能的调节机制及应用前景。 相似文献
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CpG免疫刺激序列对DNA及蛋白质疫苗的免疫增强作用 总被引:1,自引:0,他引:1
CpG逸闻刺激序列是一些以CpG为核心的具有很强免疫激活功能的核苷酸序列,对DNA疫苗及蛋白质疫苗均有极强的免疫增强作用,其作用机制可能与增强局部抗原提呈、诱发辅助T细胞活化及激活转录因子有关。CpG序列安全、经济、有效,具有较广阔的应用前景。 相似文献
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DNA甲基化是表观遗传学中的研究热点,与肿瘤的发生、发展、诊断、治疗、预后等相关。胃癌的发生、发展与DNA甲基化状态改变关系密切,研究胃癌相关基因DNA甲基化状态的改变有助于胃癌的早期发现、诊断、治疗及预后。因此,研究胃癌相关基因的甲基化状态具有一定的临床价值。 相似文献
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CpG岛甲基化检测技术比较 总被引:1,自引:0,他引:1
CpG岛过甲基化所致基因去表达是主要的表遗传学(epigenetics)改变之一,是一种在突变,缺失,异位等序列变异之外的非序列性变化。这种表遗传异常不仅与复制延迟,染色体压缩,转录机制密切相关,而且与疾病的易感性,发生发展,预后和转归均有密切相关。很多肿瘤发生都涉及到基因组甲基化的改变。包括抑癌基因的高甲基化和原癌基因的去甲基化,因此,检测甲基化的相关技术也随着甲基化研究的深入而不断推陈出新,简便高效快捷检测方法的出现极大地提高了工作效率,关键性CpG位点概念的建立增加了实验结果的实用性。 相似文献
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CpG甲基化与基因调控 总被引:2,自引:0,他引:2
CpG双核苷酸中的胞嘧啶甲基化和去甲基化在哺乳动物的基因表达中有重要的调控作用.哺乳动物基因组中有两类启动子:CpG岛启动子和CpG缺乏启动子.两种蛋白质因子通过与甲基化CpG的相互作用影响基因表达,CpG岛在基因组分析中也有广泛的用途. 相似文献
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Background
Mammalian CpG islands (CGIs) normally escape DNA methylation in all adult tissues and developmental stages. However, in our previous study we unexpectedly identified many methylated CGIs in human peripheral blood leukocytes. Methylated CpG dinucleotides convert to TpG dinucleotides through deaminization of their cytosine bases more frequently than hypomethylated CpG dinucleotides. Therefore, we wondered how methylated CGIs in germline or non-germline cells maintain their CpG-rich sequences. It is known that events such as germline hypomethylation, CpG selection, biased gene conversion (BGC), and frequent CpG fixation can contribute to the maintenance of CpG-rich sequences in methylated CGIs in germline or non-germline cells. However, it has not been investigated which of the processes maintain CpG-rich sequences of methylated CGIs in each genomic position.Results
In this study, we comprehensively examined the contribution of the processes described above to the maintenance of CpG-rich sequences in methylated CGIs in germline and non-germline cells which were classified by genomic positions. Approximately 60–80% of CGIs with high methylation in H1 cell line (H1-HM) in all the genomic positions showed a low average CpG → TpG/CpA substitution rate. In contrast, fewer than half the numbers of CGIs with H1-HM in all the genomic positions showed a low average CpG → TpG/CpA substitution rate and low levels of methylation in sperm cells (SPM-LM). Furthermore, a small fraction of CGIs with a low average CpG → TpG/CpA substitution rate and high levels of methylation in sperm cells (SPM-HM) showed CpG selection.On the other hand, independent of the positions in genes, most CGIs with SPM-HM showed a slightly higher average TpG/CpA → CpG substitution rate compared with those with SPM-LM.Conclusions
Relatively high numbers (approximately 60–80%) of CGIs with H1-HM in all the genomic positions preserve their CpG-rich sequences by a low CpG → TpG/CpA substitution rate caused mainly by their SPM-LM, and for those with SPM-HM partly by CpG selection and TpG/CpA → CpG fixation. BGC has little contribution to the maintenance of CpG-rich sequences of CGIs with SPM-HM which were classified by genomic positions.Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1286-x) contains supplementary material, which is available to authorized users. 相似文献13.
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Raghunath Chatterjee Charles Vinson 《Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms》2012,1819(7):763-770
CG methylation is an epigenetically inherited chemical modification of DNA found in plants and animals. In mammals it is essential for accurate regulation of gene expression and normal development. Mammalian genomes are depleted for the CG dinucleotide, a result of the chemical deamination of methyl-cytosine in CG resulting in TpG. Most CG dinucleotides are methylated, but ~ 15% are unmethylated. Five percent of CGs cluster into ~ 20,000 regions termed CG islands (CGI) which are generally unmethylated. About half of CGIs are associated with housekeeping genes. In contrast, the gene body, repeats and transposable elements in which CGs are generally methylated. Unraveling the epigenetic machinery operating in normal cells is important for understanding the epigenetic aberrations that are involved in human diseases including cancer. With the advent of high-throughput sequencing technologies, it is possible to identify the CG methylation status of all 30 million unique CGs in the human genome, and monitor differences in distinct cell types during differentiation and development. Here we summarize the present understanding of DNA methylation in normal cells and discuss recent observations that CG methylation can have an effect on tissue specific gene expression. We also discuss how aberrant CG methylation can lead to cancer. This article is part of a Special Issue entitled: Chromatin in time and space. 相似文献
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CpG诱发免疫反应的能力对免疫预防是一大优点 ,但在基因治疗中 ,质粒中所含的CpG基元能够阻止基因转移或导致巨大副作用 (炎症和毒性 )。本文简单综述了CpG基元的免疫学活性、主要作用和信号转导通路 ,并且针对它在基因治疗中存在的问题及可能的解决办法进行探讨。 相似文献
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