title: Oligodeoxynucleotide binding to (CTG) · (CAG) microsatellite repeats inhibits replication fork stalling, hairpin formation, and genome instability.
abstract: (CTG)(n) · (CAG)(n) trinucleotide repeat (TNR) expansion in the 3' untranslated region of the dystrophia myotonica protein kinase (DMPK) gene causes myotonic dystrophy type 1. However, a direct link between TNR instability, the formation of noncanonical (CTG)(n) · (CAG)(n) structures, and replication stress has not been demonstrated. In a human cell model, we found that (CTG)(45) · (CAG)(45) causes local replication fork stalling, DNA hairpin formation, and TNR instability. Oligodeoxynucleotides (ODNs) complementary to the (CTG)(45) · (CAG)(45) lagging-strand template eliminated DNA hairpin formation on leading- and lagging-strand templates and relieved fork stalling. Prolonged cell culture, emetine inhibition of lagging-strand synthesis, or slowing of DNA synthesis by low-dose aphidicolin induced (CTG)(45) · (CAG)(45) expansions and contractions. ODNs targeting the lagging-strand template blocked the time-dependent or emetine-induced instability but did not eliminate aphidicolin-induced instability. These results show directly that TNR replication stalling, replication stress, hairpin formation, and instability are mechanistically linked in vivo.
authors.affiliation: Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, USA. guoqi.liu@yahoo.com
authors.forename: Guoqi
authors.initials: G
authors.lastname: Liu
authors.forename: Xiaomi
authors.initials: X
authors.lastname: Chen
authors.forename: Michael
authors.initials: M
authors.lastname: Leffak
mesh_terms: D004247:DNA / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004261:DNA Replication; D042822:Genomic Instability; D006367:HeLa Cells; D006801:Humans; D009223:Myotonic Dystrophy / Q000235:genetics; D065636:Myotonin-Protein Kinase; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D019680:Trinucleotide Repeat Expansion
chemical_list: C585517:DMPK protein, human; D009838:Oligodeoxyribonucleotides; D004247:DNA; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases