表观遗传治疗的机理与抗肿瘤的临床应用

表观遗传学(epigenetics)是指在生物体DNA不发生改变的情况下,生物体获得的可遗传的表现型的改变,是遗传学的一门分支学科。肿瘤细胞的增殖分化不只是与DNA序列的变化有关,同时受到正常DNA表达发生改变,即表观遗传学的影响,因此可以采用表观遗传学的一些机理和方法来控制肿瘤的生长和增殖。表观遗传学现象有很多种,已知的有DNA甲基化、组蛋白修饰、染色质重塑及非编码RNA等四种,因此可以根据不同的机理采用不同的方法来进行表观遗传学治疗。本文就从表观遗传学治疗方式进行叙述。     

表观遗传学在食物过敏中的研究进展

食物过敏是一种严重的公共营养卫生问题，影响过敏人群的生活质量。目前，对食物过敏的研究已深入到基因层面。近年来，有文献报道表观遗传在食物过敏中发挥了不同程度的作用。本文从DNA甲基化、miRNA调控、组蛋白修饰等常见表观遗传学角度，探讨对食物过敏的影响，解析食物过敏在基因水平的形成机制。     

食品和营养的表观遗传观点和展望

正随着科学技术的发展和社会环境的改变,人们对食品与营养更加关注,越来越多的人开始注重营养均衡和食品安全。而对于表观遗传观点来说,食品与营养并不仅存在于均衡和安全的局限面中,也存在于遗传学这个生物大范围中,影响着生物的生理、病理以及各种负面内容的形成。其作用可以防止人们产生过度营养,避免代谢疾病的发生等,由此可见,对食品和营养的表观遗传观点进行分析和展     

食品生物活性物质与结直肠癌DNA甲基化异常的研究进展

DNA 甲基化是肿瘤发生的一种重要表观遗传学变化,并已被证实与结直肠癌的发生发展密切相关。本文介绍DNA 甲基化的形成机制以及重要性,结合近期国内外DNA 甲基化异常与结直肠癌关系的研究进展,总结食品生物活性物质如何通过调控甲基基团代谢或DNA 甲基化转移酶活性来调节DNA 甲基化,从而影响结直肠癌发生发展的机制。     

真菌毒素暴露对组蛋白修饰影响的研究进展

天然存在的霉菌毒素的暴露会影响人体健康。环境中的许多真菌毒素会对组蛋白修饰状态产生影响,这种表观遗传改变在疾病的发生与发展中往往发挥重要作用。近年来,真菌毒素在表观遗传学层面的致毒机制也已成为研究热点。然而截止目前,专注于真菌毒素致毒的组蛋白修饰方面的综述仍然缺乏。文章综述了黄曲霉毒素(AFB1)、脱氧雪腐镰刀菌烯醇(DON)、赭曲霉毒素(OTA)、伏马毒素(FB1)、T-2毒素等多种真菌毒素对组蛋白修饰影响的最新研究进展及其可能的作用机制,为进一步揭示环境毒素污染对人体健康的影响及食品安全风险评估提供了参考依据。     

低聚半乳糖的功能特性及其在健康食品中的应用

食物最初是用来满足人类对营养、能量或者愉悦感的需求,但如今食品的概念已经发生了变化,食品不再只是单纯的为了解除饥饿和满足人体的营养需求,还用来预防营养相关疾病、提升机体和精神状态等.诸多的研究表明人体健康与宿主肠道微生物之间存在着微妙的平衡关系.因此以合适的方式控制和维护肠道微生物菌群平衡就变得格外重要.食品可以通过强化、添加或者提高某一特定成分生物活性的方式进行功能化.在功能性食品配料中,益生菌、益生元、可溶性膳食纤维、omega3不饱和脂肪酸、亚油酸、植物抗氧化物质、维生素、矿物质、蛋白质、多肽、氨基酸、磷脂等都是经常被使用的功能性成分.目前针对肠道健康的最主要和最重要的功能性食品配料为益生菌和益生元,具有调节人体微生态平衡的作用.     

低聚半乳糖的功能特性及其在健康食品中的应用

<正>早期食品主要是用来满足人类对营养、能量或者愉悦感的需求,但如今食品的概念已经发生了变化,不单纯只为了解除饥饿和满足人体的营养需求,还用来预防营养相关疾病、提升机体和精神状态等。诸多的研究表明人体健康与宿主肠道微生物之间存在着微妙的平衡关系,因此以合适的方式控制和维护肠道微生物菌群平衡就变得格外重要。食品可以通过强化、添加或者提高某一特定成分生物活性的方式进行功能化。在功能性食品配料中,益生菌、益生     

中国科学家首次构建猪脂肪和肌肉DNA甲基化图谱

由四川农业大学和深圳华大基因研究院主导,中、美、英、加等4国共12个单位的50多位研究人员合作完成的研究成果《猪脂肪和肌肉组织的基因组甲基化图谱》,22日在国际著名学术杂志《自然-通讯》上发表。该研究首次构建了猪不同部位脂肪和肌肉组织的DNA甲基化图谱,为预防人类肥胖疾病的发生和促进猪肌肉生长和脂肪沉积这一重要经济性状的研究,奠定了重要的表观遗传学基础。该研究对促进猪作为人类肥胖     

益生菌在功能食品中的应用研究

作为一种生理菌群,益生菌对人体肠道有诸多益处,对高血压、糖尿病、高血脂以及癌症等多种疾病都有预防作用。同时,益生菌还具有良好的营养保健功能,因而被人们广泛应用于食品领域中,如功能性食品、食品添加剂等,深受广大消费者的喜爱。基于此,本文阐述了益生菌的定义和种类,分析了益生菌的营养保健作用,包括抑制病原菌生长和繁殖,优化肠道菌群结构;提高机体免疫力,刺激免疫应答;降低肿瘤发病率,抑制癌细胞生长;延缓机体衰老,清除机体自由基;改善机体的血脂情况,降低胆固醇含量等,并对益生菌在功能食品中的应用进行了论述,希望能进一步拓展益生菌的应用范围。     

功能性食品与药食同源之说探析

功能性食品代表世界食品发展的新潮流，有二十一世纪食品之称。功能性食品与我国传统的饮食疗法在内涵上颇为相同，两者都包含食品的营养与感官性能，又具有药品的防治疾病功能，从我国传统的食药物品中开发功能性食品有着良好的前景。功能性食品一词首见于１９８７年日本文部省（文教部）在“食品功能的系统性解释与展开”科研成果报告中，把过去常用的食品特性改称食品功能。１９８９年４月厚生省（卫生福利部）对功能性食品予以进一步明确并作如下定义：“食品成分所具有的机体防御、节律调整和疾病防活等机体调节功能，使之能对人体充分发挥效用所设计、加工的食品称为功能性食品。”     

Epigenetic alteration of the donor cells does not recapitulate the reprogramming of DNA methylation in cloned embryos

Epigenetic reprogramming is a prerequisite process during mammalian development that is aberrant in cloned embryos. However, mechanisms that evolve abnormal epigenetic reprogramming during preimplantation development are unclear. To trace the molecular event of an epigenetic mark such as DNA methylation, bovine fibroblasts were epigeneticallyaltered by treatment with trichostatin A (TSA) and then individually transferred into enucleated bovine oocytes. In the TSA-treated cells, expression levels of histone deacetylases and DNA methyltransferases were reduced, but the expression level of histone acetyltransferases such as Tip60 and histone acetyltransferase 1 (HAT1) did not change compared with normal cells. DNA methylation levels of non-treated (normal) and TSA-treated cells were 64.0 and 48.9% in the satellite I sequence (P < 0.05) respectively, and 71.6 and 61.9% in the alpha-satellite sequence respectively. DNA methylation levels of nuclear transfer (NT) and TSA-NT blastocysts in the satellite I sequence were 67.2 and 42.2% (P < 0.05) respectively, which was approximately similar to those of normal and TSA-treated cells. In the alpha-satellite sequence, NT and TSA-NT embryos were substantially demethylated at the blastocyst stage as IVF-derived embryos were demethylated. The in vitro developmental rate (46.6%) of TSA-NT embryos that were individually transferred with TSA-treated cells was higher than that (31.7%) of NT embryos with non-treated cells (P < 0.05). Our findings suggest that the chromatin of a donor cell is unyielding to the reprogramming of DNA methylation during preimplantation development, and that alteration of the epigenetic state of donor cells may improve in vitro developmental competence of cloned embryos.     

The capability of reprogramming the male chromatin after fertilization is dependent on the quality of oocyte maturation

The present experiments compared the ability of pig oocytes matured either in vivo or in vitro to structurally reorganize the penetrated sperm chromatin into male pronucleus (PN) and to carry out, in parallel, the epigenetic processes of global chromatin methylation and acetylation, 12-14 h after in vitro fertilization (IVF). In addition, PN distribution of histone deacetylase (HDAC), a major enzyme interfacing DNA methylation and histone acetylation, was investigated. The ability of the oocyte to operate an efficient block to polyspermy was markedly affected by maturation. The monospermic fertilization rate was significantly higher for in vivo than for in vitro matured (IVM) oocytes (P < 0.01) which, furthermore, showed a reduced ability to transform the chromatin of penetrated sperm into male PN (P < 0.01). Indirect immunofluorescence analysis of global DNA methylation, histone acetylation and HDAC distribution (HDAC-1, -2 and -3), carried out in monospermic zygotes that reached the late PN stage, showed that IVM oocytes also had a reduced epigenetic competence. In fact, while in about 80% of in vivo matured and IVF oocytes the male PN underwent a process of active demethylation and showed a condition of histone H4 hyperacetylation, only 40% of IVM/IVF zygotes displayed a similar PN remodelling asymmetry. Oocytes that carried out the first part of maturation in vivo (up to germinal vesicle breakdown; GVBD) and then completed the process in vitro, displayed the same PN asymmetry as oocytes matured entirely in vivo. A crucial role of HDAC in the establishment of PN acetylation asymmetry seems to be confirmed by the use of HDAC inhibitors as well as by the abnormal distribution of the enzyme between the two PN in IVM zygotes. Collectively, these data demonstrated that some pig IVM oocytes fail to acquire full remodelling competence which is independent from their ooplasmic ability to morphologically reorganize the sperm nucleus into PN.