To Explore the Role of R-Loops in the Decreased Transcript Production of Repetitive DNA Sequences in Spt4-deficient Cells
| Autor: | Tse-Yi Lin, 林則毅 |
|---|---|
| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 Expanded CAG tri-nucleotide repeats are linked to multiple neurodegenerative disorders, including Spinocerebellar ataxia and Huntington's disease (HD). While the toxicity of gene product from CAG expansion has been characterized intensively, the impact of CAG tri-nucleotide on gene expression and genome instability is largely unknown. R-loop, a nucleic acid structure consisting of nascent mRNA and DNA template, was considered as a negative regulator for the gene expression and genome stability. This structural feature was identified in transcribed DNA templates containing expanded CAG repeats. In our earlier studies, we found that the transcription of genes containing expanded CAG repeats, such as mutant Huntingtin gene, is selectively down-regulated by Spt4/Supt4h deficiency. Later, we discovered that such changes of gene expression can be partially rescued by cellular factors that eliminate R-loop. Here, we demonstrate that R-loop is detectable in transcribed DNA template containing expanded CAG repeats by DNA immune-precipitation assay. We reveal the role of Spt4 in R-loop formation and dissect the molecular mechanism underlying the transcription reduction of DNA template containing a long stretch of CAG repeats in Spt4 deficient cells. We also characterize the role of another transcription elongation complex THO in R-loop formation and make a comparison with Spt4. In addition, we assess the presence of R-loop in other repetitive nucleotide sequences and measure its impact on these gene expressions. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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