|
|||||||||
| This e-mail address is being protected from spam bots, you need JavaScript enabled to view it | Assistant: |
| Lewis Thomas Lab-353 | This e-mail address is being protected from spam bots, you need JavaScript enabled to view it |
| Phone: 609-258-6380 | Phone: 609-258-9197 |
DNA Mismatch Repair and Colorectal Cancer
In the early 1990’s the most common form of hereditary colon cancer, hereditary non-polyposis colon cancer (HNPCC) was linked to defects in DNA mismatch repair. DNA mismatch repair is critical for maintaining the fidelity of genetic material in organisms ranging from prokaryotes to humans. Without an intact DNA mismatch repair system DNA begins to accumulate changes, many of which will be deleterious to the cell or organism. Cancer is a consequence of a collection of alterations primarily at the DNA level that result in abnormal cellular proliferation. If a cell no longer has DNA mismatch repair then oncogenesis is greatly accelerated. For example, HNPCC individuals inheriting a defective mismatch repair locus have an 80-90% chance of manifesting cancer before the age of 50.
The high penetrance and early age of onset of the disease underscores the need for aggressive identification and screening of susceptible individuals. After the establishment of the connection between the HNPCC and DNA mismatch repair, many germline mutations have been mapped in afflicted families. Most mutations reside in one two genes, MSH2 (~30%) and MLH1 (~33%). Included among these mapped alterations is a collection of nearly 50 missense mutations found in hMSH2. It is part of the objective of our research to determine whether the missense mutations found at the mapped hMSH2 loci result in a dysfunctional protein (pathogenic polymorphisms) or if the missense changes are likely to be benign polymorphisms in the human population. If missense mutations are to be used in genetic counseling, it is imperative to determine which changes result in a defective protein.
We use the yeast Saccharomyces cerevisiae as a model organism to understand eukaryotic DNA mismatch repair. We have created most of the mapped missense mutation listed in the human databases in the cognate yeast MSH2 gene and assayed for defects in DNA mismatch repair. We also work towards understanding in what way are the variant proteins defective for mismatch repair. Finally, we also take a molecular and genetic approach to identify novel genes that participate in eukaryotic DNA mismatch repair.
Cell and Nuclear Fusion (Collaboration with Mark Rose)
A second research interest also uses yeast as a model organism to understand a fundamental biological process, cell fusion. Cell fusion is an essential process for the propagation of eukaryotic species that include a sexual mode of reproduction. One example of this is sperm-egg fusion resulting in a human embryo. Cell fusion also occurs during development for the formation of muscle and bone. The creation of one cell from the fusion of two progenitor cells is a perilous biological event. Cell fusion must be both complete and precise, allowing cytoplasmic continuity while avoiding cell lysis. Mating of the yeast S. cerevisiae is an ideal model system for studying the events and regulation of cell fusion. In yeast, mating is not essential for viability and cells can be propagated asexually. Therefore, cell and nuclear fusion mutants can be generated without dire consequences to the organism. The characterization of such mutants has facilitated the identification of several genes involved in the efficiency and control of mating. We take a genetic, cell biological and biochemical approach to studying the events of cell and nuclear fusion.
Selected Publications
Hayes AP, Sevi LA, Feldt MC, Rose MD, Gammie AE. (2009) Reciprocal regulation of nuclear import of the yeast MutSalpha DNA mismatch repair proteins Msh2 and Msh6. DNA Repair (Amst). 8: 739-751. PubMedGammie AE. (2008) Ultrastructural analysis of cell fusion in yeast. Methods Mol Biol. 475: 197-211. PubMed
Gammie AE, Erdeniz N, Beaver J, Devlin B, Nanji A, Rose MD. (2007) Functional characterization of pathogenic human MSH2 missense mutations in Saccharomyces cerevisiae. Genetics 177: 707-721. PubMed
Lahav R, Gammie AE, Tavazoie S, Rose MD. (2006) The transcription factor Kar4p has a global role in regulating the yeast pheromone response pathway. Mol Cell Biol 27: 818-829. PubMed
Gammie AE, Erdeniz N. (2004) Characterization of pathogenic human MSH2 missense mutations using yeast as a model system: a laboratory course in molecular biology. Cell Biol Ed 3: 31-48.
Fitch PG, Gammie AE, Lee DJ, de Candal VB, Rose MD. (2004) Lrg1p Is a Rho1 GTPase-activating protein required for efficient cell fusion in yeast. Genetics 168: 733-746. PubMed
Gammie AE, Rose MD. (2002) Assays of cell and nuclear fusion. Methods Enzymol 351: 477-498. PubMed
Gammie AE, Stewart BG, Scott CF, Rose MD. (1999) The two forms of karyogamy transcription factor Kar4p are regulated by differential initiation of transcription, translation, and protein turnover. Mol Cell Biol 19: 817-825. PubMed
Miller RK, Heller KK, Frisen L, Wallack DL, Loayza D, Gammie AE, Rose MD. (1998) The kinesin-related proteins, Kip2p and Kip3p, function differently in nuclear migration in yeast. Mol Biol Cell 9: 2051-2068. PubMed
Gammie AE, Brizzio V, Rose MD. (1998) Distinct morphological phenotypes of cell fusion mutants. Mol Biol Cell 9: 1395-1410. PubMed
Brizzio V, Gammie AE, Rose MD. (1998) Rvs161p interacts with Fus2p to promote cell fusion in Saccharomyces cerevisiae. J Cell Biol 141: 567-584. PubMed
Kurihara LJ, Stewart BG, Gammie AE, Rose MD. (1996) Kar4p, a karyogamy-specific component of the yeast pheromone response pathway. Mol Cell Biol 16: 3990-4002. PubMed
Brizzio V, Gammie AE, Nijbroek G, Michaelis S, Rose MD. (1996) Cell fusion during yeast mating requires high levels of a-factor mating pheromone. J Cell Biol 135: 1727-1739. PubMed
Gammie AE, Rose MD. (1995) Identification and characterization of CEN12 in the budding yeast Saccharomyces cerevisiae. Curr Genet 28: 512-516. PubMed
Gammie AE, Kurihara LJ, Vallee RB, Rose MD. (1995) DNM1, a dynamin-related gene, participates in endosomal trafficking in yeast. J Cell Biol 130: 553-566. PubMed
Gammie AE, Tolmasky ME, Crosa JH. (1993) Functional characterization of a replication initiator protein. J Bacteriol 175: 3563-3569. PubMed
Tolmasky ME, Gammie AE, Crosa JH. (1992) Characterization of the recA gene of Vibrio anguillarum. Gene 110: 41-48. PubMed
Gammie AE, Crosa JH. (1991) Roles of DNA adenine methylation in controlling replication of the REPI replicon of plasmid pColV-K30. Mol Microbiol 5: 495-503. PubMed
Gammie AE, Crosa JH. (1991) Co-operative autoregulation of a replication protein gene. Mol Microbiol 5: 3015-3023. PubMed
Perez-Casal JF, Gammie AE, Crosa JH. (1989). Nucleotide sequence analysis and expression of the minimum REPI replication region and incompatibility determinants of pColV-K30. J Bacteriol 171: 2195-2201. PubMed
Gammie AE, Ruben LN. (1986) The phylogeny of macrophage function: antigen uptake and degradation by peritoneal exudate cells of two amphibian species and CAF1 mice. Cell Immunol 100: 577-583. PubMed