title: Identification of a novel deletion mutant strain inSaccharomyces cerevisiaethat results in a microsatellite instability phenotype.
abstract: The DNA mismatch repair (MMR) pathway corrects specific types of DNA replication errors that affect microsatellites and thus is critical for maintaining genomic integrity. The genes of the MMR pathway are highly conserved across different organisms. Likewise, defective MMR function universally results in microsatellite instability (MSI) which is a hallmark of certain types of cancer associated with the Mendelian disorder hereditary nonpolyposis colorectal cancer. (Lynch syndrome). To identify previously unrecognized deleted genes or loci that can lead to MSI, we developed a functional genomics screen utilizing a plasmid containing a microsatellite sequence that is a host spot for MSI mutations and the comprehensive homozygous diploid deletion mutant resource forSaccharomyces cerevisiae. This pool represents a collection of non-essential homozygous yeast diploid (2N) mutants in which there are deletions for over four thousand yeast open reading frames (ORFs). From our screen, we identified a deletion mutant strain of thePAU24gene that leads to MSI. In a series of validation experiments, we determined that thisPAU24mutant strain had an increased MSI-specific mutation rate in comparison to the original background wildtype strain, other deletion mutants and comparable to a MMR mutant involving theMLH1gene. Likewise, in yeast strains with a deletion ofPAU24, we identified specificde novoindel mutations that occurred within the targeted microsatellite used for this screen.
authors.affiliation: Division of Oncology, Department of Medicine, Stanford University School of Medicine, Stanford, CA, United States, 94305 ; Stanford Genome Technology Center, Stanford University, Palo Alto, CA, United States, 94304.
authors.forename: Hanlee P
authors.initials: HP
authors.lastname: Ji
authors.forename: Shannon
authors.initials: S
authors.lastname: Morales
authors.forename: Katrina
authors.initials: K
authors.lastname: Welch
authors.forename: Cam
authors.initials: C
authors.lastname: Yuen
authors.forename: Kyle
authors.initials: K
authors.lastname: Farnam
authors.forename: James M
authors.initials: JM
authors.lastname: Ford