title: Effects of Friedreich's ataxia GAA repeats on DNA replication in mammalian cells.
abstract: Friedreich's ataxia (FRDA) is a common hereditary degenerative neuro-muscular disorder caused by expansions of the (GAA)n repeat in the first intron of the frataxin gene. The expanded repeats from parents frequently undergo further significant length changes as they are passed on to progeny. Expanded repeats also show an age-dependent instability in somatic cells, albeit on a smaller scale than during intergenerational transmissions. Here we studied the effects of (GAA)n repeats of varying lengths and orientations on the episomal DNA replication in mammalian cells. We have recently shown that the very first round of the transfected DNA replication occurs in the lack of the mature chromatin, does not depend on the episomal replication origin and initiates at multiple single-stranded regions of plasmid DNA. We now found that expanded GAA repeats severely block this first replication round post plasmid transfection, while the subsequent replication cycles are only mildly affected. The fact that GAA repeats affect various replication modes in a different way might shed light on their differential expansions characteristic for FRDA.
authors.affiliation: Department of Biochemistry and Molecular Biology, Penn State University, University Park, PA 16802, USA.
authors.forename: Gurangad S
authors.initials: GS
authors.lastname: Chandok
authors.forename: Mayank P
authors.initials: MP
authors.lastname: Patel
authors.forename: Sergei M
authors.initials: SM
authors.lastname: Mirkin
authors.forename: Maria M
authors.initials: MM
authors.lastname: Krasilnikova
mesh_terms: D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D004247:DNA / Q000737:chemistry; D004261:DNA Replication; D005621:Friedreich Ataxia / Q000235:genetics*; D004854:Herpesvirus 4, Human / Q000235:genetics; D006801:Humans; D033862:Iron-Binding Proteins / Q000235:genetics*; D010957:Plasmids / Q000235:genetics; D018741:Replication Origin; D013539:Simian virus 40 / Q000235:genetics; D019680:Trinucleotide Repeat Expansion; D000096923:Frataxin
chemical_list: D004247:DNA; D033862:Iron-Binding Proteins; D000096923:Frataxin