Deficiency in classical nonhomologous end-joining-mediated repair of transcribed genes is linked to SCA3 pathogenesis
| Autor: | Tetsuo Ashizawa, Partha S. Sarkar, Velmarini Vasquez, Xu Chen, Patrícia Maciel, Weihan Huai, Anirban Chakraborty, Muralidhar L. Hegde, Tatiana Venkova, Altaf H. Sarker, Sara Duarte-Silva, Nisha Tapryal, Gourisankar Ghosh, Tapas K. Hazra, Joy Mitra |
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| Rok vydání: | 2020 |
| Předmět: |
Male
DNA End-Joining Repair Mutant Induced Pluripotent Stem Cells RNA polymerase II Biology Cell Line Animals Genetically Modified 03 medical and health sciences Mice 0302 clinical medicine Plasmid Transcription (biology) Animals Humans DNA Breaks Double-Stranded RNA Small Interfering Ataxin-3 Gene 030304 developmental biology Aged 80 and over 0303 health sciences Multidisciplinary Brain Machado-Joseph Disease Middle Aged Biological Sciences 3. Good health Cell biology Complementation Non-homologous end joining Repressor Proteins Disease Models Animal Phosphotransferases (Alcohol Group Acceptor) DNA Repair Enzymes Gene Knockdown Techniques Mutation biology.protein Drosophila Female RNA Polymerase II Trinucleotide repeat expansion Peptides 030217 neurology & neurosurgery |
| Zdroj: | Proc Natl Acad Sci U S A |
| ISSN: | 1091-6490 |
| Popis: | Spinocerebellar ataxia type 3 (SCA3) is a dominantly inherited neurodegenerative disease caused by CAG (encoding glutamine) repeat expansion in the Ataxin-3 (ATXN3) gene. We have shown previously that ATXN3-depleted or pathogenic ATXN3-expressing cells abrogate polynucleotide kinase 3'-phosphatase (PNKP) activity. Here, we report that ATXN3 associates with RNA polymerase II (RNAP II) and the classical nonhomologous end-joining (C-NHEJ) proteins, including PNKP, along with nascent RNAs under physiological conditions. Notably, ATXN3 depletion significantly decreased global transcription, repair of transcribed genes, and error-free double-strand break repair of a 3'-phosphate-containing terminally gapped, linearized reporter plasmid. The missing sequence at the terminal break site was restored in the recircularized plasmid in control cells by using the endogenous homologous transcript as a template, indicating ATXN3's role in PNKP-mediated error-free C-NHEJ. Furthermore, brain extracts from SCA3 patients and mice show significantly lower PNKP activity, elevated p53BP1 level, more abundant strand-breaks in the transcribed genes, and degradation of RNAP II relative to controls. A similar RNAP II degradation is also evident in mutant ATXN3-expressing Drosophila larval brains and eyes. Importantly, SCA3 phenotype in Drosophila was completely amenable to PNKP complementation. Hence, salvaging PNKP's activity can be a promising therapeutic strategy for SCA3. |
| Databáze: | OpenAIRE |
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