DNA TRIPLET REPEAT PROPERTIES AND EXPANSION

DNA 三联体重复特性和扩展

• 批准号: 6107767
• 负责人: Robert Dale Wells
• 金额: --
• 依托单位: TEXAS A&M AGRILIFE RESEARCH
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-07-01 至 1999-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6107767
• 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.

至少七种人类遗传疾病涉及突变三核苷酸重复 （CCG 和 CTG）。 其中包括脆性 X 综合征、突变导致 密切相关的脆弱部位、强直性肌营养不良、脊柱延髓肌 萎缩症、亨廷顿病、脊髓小脑性共济失调 1 型，以及 齿状核红核-苍白球路易体萎缩。 三联体重复次数 从正常人到携带者再到患病者，急剧增加 个人。 不稳定序列拷贝数的增加 后代解释了非孟德尔遗传特性 称为“预期”。 该实验室已经研究了近三个非 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 结构和这些能力能够经历 复制过程中的滑移解释了发现的“诱变突变” 人类遗传学家。 我们将对所有十种生物进行生化、物理和遗传学研究 重组质粒、DNA 聚合物中的重复三联体序列 低聚物。 我们的结论是 CTG 重复形成非 B 结构 源自 2D 凝胶电泳实验、化学和酶促实验 探针分析、与核小体定位相关的电镜测定，以及 CTG 三联体重复中的 DNA 聚合酶暂停位点。 的作用 将探讨 C 甲基化对 DNA 构象特征的影响。 原核生物中发现CTG序列的扩增和缺失 细胞；该系统可以作为理解的重要模型 扩展与人类的发病年龄和严重程度有关 遗传疾病。 此外，三联体重复序列在遗传中的作用 将研究真核染色体中的重组。