title: Transcription-induced DNA toxicity at trinucleotide repeats: double bubble is trouble.
abstract: Trinucleotide repeats (TNR) are a blessing and a curse. In coding regions, where they are enriched, short repeats offer the potential for continuous, rapid length variation with linked incremental changes in the activity of the encoded protein, a valuable source of variation for evolution. But at the upper end of these benign and beneficial lengths, trinucleotide repeats become very unstable, with a dangerous bias toward continual expansion, which can lead to neurological diseases in humans. The mechanisms of expansion are varied and the links to disease are complex. Where they have been delineated, however, they have often revealed unexpected, fundamental aspects of the underlying cell biology. Nowhere is this more apparent than in recent studies, which indicate that expanded CAG repeats can form toxic sites in the genome, which can, upon interaction with normal components of DNA metabolism, trigger cell death. Here we discuss the phenomenon of TNR-induced DNA toxicity, with special emphasis on the role of transcription. Transcription-induced DNA toxicity may have profound biological consequences, with particular relevance to repeat-associated neurodegenerative diseases.
authors.affiliation: Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX USA. yunful@bcm.edu
authors.forename: Yunfu
authors.initials: Y
authors.lastname: Lin
authors.forename: John H
authors.initials: JH
authors.lastname: Wilson
mesh_terms: D017209:Apoptosis / Q000235:genetics*; D064007:Ataxia Telangiectasia Mutated Proteins; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D004260:DNA Repair / Q000235:genetics; D006801:Humans; D019636:Neurodegenerative Diseases / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D019680:Trinucleotide Repeat Expansion; D018911:Trinucleotide Repeats / Q000235:genetics*
chemical_list: D018797:Cell Cycle Proteins; D004247:DNA; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases