叶酸、核黄素缺乏及亚甲基四氢叶酸还原酶基因多态性对人类遗传物质稳定性的影响

发布时间：2018-02-10 19:27

本文关键词： 叶酸核黄素亚甲基四氢叶酸还原酶(MTHFR) 多重聚合酶链式反应-限制性片段长度多态(Multiplex PCR-RFLP) 胞质阻滞微核分析(CBMN) 遗传稳定性　出处：《云南师范大学》2006年硕士论文　论文类型：学位论文

【摘要】：叶酸是人体正常发育的重要微营养物质，其涉及dUMP到dTMP的合成，同时通过同型半胱氨酸(HC)合成甲硫氨酸(Met)和S-腺苷甲硫氨酸(SAM)的生化过程影响DNA的甲基化。在叶酸代谢中，亚甲基四氢叶酸还原酶(MTHFR)催化5，，10-亚甲基四氢叶酸(5，10-methylene THF)向5-甲基四氢叶酸(5-methylTHF)转化，MTHFR基因位点突变可导致MTHFR活性降低，同型半胱氨酸水平升高。黄素腺嘌呤二核苷酸(FAD)是MTHFR的辅酶，而FAD的前体为核黄素。因此，叶酸、核黄素缺乏及MTHFR基因多态性可能对DNA结构和DNA甲基化过程、基因表达、染色体分离等形成一定的胁迫作用。本研究采用多重聚合酶链式反应-限制性片段长度多态(Multiplex PCR-RFLP)技术筛查MTHFR基因677位点、1298位点基因型在正常个体与乳腺癌患者中的多态分布特点；以胞质阻滞微核分析(CBMN)研究各种MTHFR基因型个体淋巴细胞在叶酸、核黄素缺乏以及不同浓度组合条件下产生的遗传与细胞毒性效应，评价不同MTHFR基因型、叶酸与核黄素不同组合对人类基因组稳定性的影响。研究表明： 1、677位点突变纯合体(TT)在乳腺癌患者(n=122)和对照组(n=99)中的分布频率分别为18.03％和9.09％，无显著性差异；1298位点突变纯合体(CC)在乳腺癌患者(n=119)和对照组(n=98)中的分布频率分别为9.25％和7.15％，也未表现显著性差异；677、1298位点组合基因型在乳腺癌患者和对照组中的分布频率无显著性差异。 2、在本实验浓度范围内，乳腺癌患者及对照个体遗传损伤和细胞损伤指标均具有以下趋势：高叶酸低核黄素组合浓度(HFLR)＜高叶酸高核黄素组(HFHR)＜低叶酸高核黄素组(LFHR)＜低叶酸低核黄素组(LFLR)。提示在叶酸含量较低时，过量的核黄素会对细胞造成损伤。分析各种因素对损伤的贡献发现，叶酸对遗传物质稳定性的影响最大，乳腺癌背景及核黄素对遗传物质稳定性的影响不显著。 3、本实验还讨论了基因型、叶酸、核黄素对淋巴细胞遗传损伤的影响及三者对造成遗传损伤的交互作用。结果发现叶酸、677位点基因型对细胞遗传损伤有显著影响，而核黄素仅对核质桥(NPB)的产生有显著影响，三者对造成遗传损伤
[Abstract]:Folic acid is an important micronutrient in the normal development of human body. It involves the synthesis of dUMP to dTMP, and the biochemical process of synthesis of methionine (Meta) and S-adenosine methionine (S- adenosine methionine), which affects the methylation of DNA. Methylene tetrahydrofolate reductase (MTHFR) catalyzes the transformation of 5-methyl-tetrahydrofolate 510-methylene to 5-methyl-tetrahydrofolate (5-methyl-tetrahydrofolate). The mutation of MTHFR gene site can lead to the decrease of MTHFR activity and increase of homocysteine level. Flavin adenine dinucleotide (Fad) is a coenzyme of MTHFR. Therefore, folic acid, riboflavin deficiency and MTHFR gene polymorphism may exert some stress on DNA structure and DNA methylation, gene expression and chromosome segregation. In this study, multiplex polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to screen the polymorphism distribution of MTHFR gene 677 locus and 1298 locus in normal individuals and breast cancer patients. Cytoplasmic block micronucleus analysis was used to study the genetic and cytotoxic effects of individual lymphocytes of various MTHFR genotypes on folic acid, riboflavin deficiency and combination of different concentrations, and to evaluate different MTHFR genotypes. Effects of different combinations of folic acid and riboflavin on the stability of human genome. Research shows that:. The distribution frequencies of 1,677 locus homozygote in breast cancer patients were 18.03% and 9.09, respectively. There was no significant difference in the frequency of 1,677 locus mutation homozygotes in breast cancer patients (n = 119) and control group (n = 9.25%). There was no significant difference in genotype distribution between breast cancer patients and controls. 2, within the concentration range of this experiment, The genetic damage and cell damage index of breast cancer patients and control individuals showed the following trends: high folic acid low riboflavin concentration (HFLR) < high folate high riboflavin group (HFHRs) < low folate high riboflavin group (LFLRR) < low folate low riboflavin group (LFLRR). When folic acid content is low, Analysis of the contribution of various factors to the damage found that folic acid had the greatest influence on the stability of genetic material, while the background of breast cancer and riboflavin had no significant effect on the stability of genetic material. 3. The effects of genotype, folic acid and riboflavin on genetic damage of lymphocytes and their interaction with genetic damage were also discussed. Riboflavin only had a significant effect on the production of NPB, and three of them caused genetic damage.
【学位授予单位】：云南师范大学
【学位级别】：硕士
【学位授予年份】：2006
【分类号】：R346

【引证文献】