DNA TRIPLET REPEAT PROPERTIES AND EXPANSION

DNA 三联体重复特性和扩展

• 批准号: 6204267
• 负责人: Robert Dale Wells
• 金额: $ 11.38万
• 依托单位: TEXAS A&M AGRILIFE RESEARCH
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2001-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6204267
• 关键词: CHO cells; DNA directed DNA polymerase; DNA methylation; Huntington's disease; adenine phosphoribosyltransferase; cerebellar ataxia /dyskinesia; electron microscopy; enzyme activity; fragile X syndromes; gel electrophoresis; genetic recombination; human genetic material tag; myotonic dystrophy; nucleic acid probes; nucleic acid repetitive sequence; nucleic acid structure; nucleosomes; oligonucleotides; plasmids; recombinant DNA

At least seven human genetic disorders involve mutant trinucleotide repeats (CCG and CTG). These include fragile X syndrome, mutation resulting in a closely related fragile site, myotonic dystrophy, spino-bulbar muscular atrophy, Huntington's disease, spino-cerebellar ataxia type 1, and dentatorubral-pallidoluysian atrophy. The number of triplet repeats increases dramatically from normal individuals to carriers to afflicted individuals. This increase in copy number of the unstable sequence with subsequent generations accounts for the non-Mendelian genetic property termed "anticipation". This laboratory has investigated non-B DNA structures for almost three decades. Several types of preliminary investigations demonstrate that these and related simple repeating sequences adopt unusual DNA structures. We believe that these non-B structures and these capacities to undergo slippage during replication account for the "mutagenic mutations" found by human geneticists. We shall perform biochemical, physical, and genetic studies on all ten repeating triplet sequences in recombinant plasmids, DNA polymers, and oligomers. Our conclusions that CTG repeats form non-B structures are derived from 2D gel electrophoresis experiments, chemical and enzymatic probe analyses, EM determinations related to nucleosome positioning, and DNA polymerase pause sites in the CTG triplet repeats. The role of methylation of C on DNA conformational features will be explored. Expansion and deletion of CTG sequences has been found in procaryotic cells; this system may serve as an important model for understanding expansion which is related tot he age of onset and severity of human genetic diseases. Also, the role of triplet repeat sequences in genetic recombination in eucaryotic chromosomes will be investigated.

至少有七种人类遗传疾病涉及突变的三核苷酸重复序列 (CCG CTG）。 这些包括脆性X综合征，突变导致 密切相关的脆性部位，强直性肌营养不良，脊髓延髓肌 萎缩、亨廷顿病、脊髓-小脑共济失调1型，和 齿状核红核苍白球路易氏体萎缩 三重重复的数目 从正常人到携带者再到患病者 个体 这种不稳定序列拷贝数的增加， 随后的世代解释了非孟德尔遗传特性 被称为“期待”。 这个实验室已经研究了近三年的非B DNA结构， 几十年 几种类型的初步调查表明， 这些和相关的简单重复序列采用不寻常的DNA结构。 我们相信这些非B结构和这些承受能力 复制过程中的滑动解释了通过 人类遗传学家 我们将对这10种植物进行生物化学、物理和遗传学研究 在重组质粒、DNA聚合物中重复三联体序列， 低聚物 CTG重复序列形成非B结构的结论是： 来自2D凝胶电泳实验，化学和酶 探针分析，与核小体定位相关的EM测定，以及 CTG三联体重复中的DNA聚合酶暂停位点。 的作用 将探索C甲基化对DNA构象特征的影响。 CTG序列的扩增和缺失已在原核细胞中发现。 细胞;这个系统可以作为理解的重要模型 与发病年龄和人类疾病严重程度有关的扩张 遗传病 此外，三联体重复序列在遗传学中的作用 将研究真核染色体中的重组。