Expansions, contractions, and fragility of the spinocerebellar ataxia type 10 pentanucleotide repeat in yeast

Nicole Cherng, Alexander A. Shishkin, Lucas I. Schlager, Ryan H. Tuck, Laura Sloan, Robert Matera, Partha S. Sarkar, Tetsuo Ashizawa, Catherine H. Freudenreich, Sergei M. Mirkin

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


Spinocerebellar ataxia 10 (SCA10) is an autosomal dominant disease caused by large-scale expansions of the (ATTCT)n repeat within an intron of the human ATXN10 gene. In contrast to other expandable repeats, this pentanucleotide repeat does not form stable intra- or interstranded DNA structures, being a DNA unwinding element instead. We analyzed the instability of the (ATTCT)n repeat in a yeast experimental system, where its expansions led to inactivation of the URA3 reporter gene. The inactivation was due to a dramatic decrease in the mRNA levels owing to premature transcription termination and RNA polyadenylation at the repeat. The rates of expansions strongly increased with the repeat's length, mimicking genetic anticipation in human pedigrees. A first round of genetic analysis showed that a functional TOF1 gene precludes, whereas a functional RAD5 gene promotes, expansions of the (ATTCT)n repeat. We hypothesize that repeat expansions could occur upon fortuitous template switching during DNA replication. The rate of repeat contractions was elevated in the Tof1 knockout strain, but it was not affected by the RAD5 gene. Supporting the notion of replication irregularities, we found that (ATTCT)n repeats also cause length-dependent chromosomal fragility in yeast. Repeat-mediated fragility was also affected by the Tof1 and Rad5 proteins, being reduced in their absence.

Original languageEnglish (US)
Pages (from-to)2843-2848
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number7
StatePublished - Feb 15 2011


  • DNA repair
  • DNA repeats
  • Genome instability

ASJC Scopus subject areas

  • General


Dive into the research topics of 'Expansions, contractions, and fragility of the spinocerebellar ataxia type 10 pentanucleotide repeat in yeast'. Together they form a unique fingerprint.

Cite this