Greg Freyer, PhD

Greg Freyer’s major research interest is in understanding the cell’s response to environmental agents that damage DNA. His research focuses on the recQ DNA helicases family of enzymes and their interaction with proteins of the homologous recombination pathway that work together in the repair of DNA double strand breaks and recovery from stalled replication, both potentially lethal and mutagenic events. Studies in the laboratory are beginning to unravel the complex set of molecular events that are critical for maintaining genomic stability following DNA damage. He and his team of researchers have found a role for RecQ helicases in both the determination of the mechanism of DNA repair and in blocking crossover formation. In collaboration with other experts in environmental health sciences, his group is also investigating whether a polymorphic form of the DNA repair protein XRCC1, shown to increase p53 mutation rates, is defective in its biochemical activity. Dr Freyer is director of Academic Affairs for the Department Environmental Health Sciences, serves as chair of the Steering Committee, the faculty representative on the MSPH Strategic Planning Committee, and is active on several other committees including, the subcommittee on Diversity, the subcommittee on Doctoral Policy and Planning, the Summer Research Program for Science Teachers. Dr Freyer holds a joint appointment in the Department of Cell Biology and Pathobiology.

Selected Publications:

Marchetti MA, Kumar S, Hartsuiker E, Maftahi M, Carr AM, Freyer GA, Burhans WC, and Huberman, JA "A single unbranched S-phase DNA damage and replication fork blockage checkpoint pathway" Proceedings of the National Academy of Science 99, 7472-7477, 2002

Maftahi, M, Hope, JC, Delgado-Cruzata, L, Han, CS and Freyer, GA "The severe slow growth of Δsrs2 Δrqh1 in Schizosaccharomyces pombe is suppressed by loss of recombination and checkpoint genes." Nucleic Acids Research 30, 4781-92, 2002

Hope, JC, Maftahi, M and Freyer, GA "A postsynaptic role for Rhp55/57 in recovery from replication arrest is revealed in Δrqh1 mutants" Genetics 170, 519-531, 2005

Chang, M, Bellaoui, M, Zhang, C, Desai, R, Morozov, P, Delgado-Cruzata, L, Rothstein, R, Boone, C, Freyer, GA, and Brown, GW "RMI1/NCE4, a suppressor of genome instability, encodes a member of the RecQ helicase/Topo III complex" European Molecular Biology Organization 24, 2024-2033, 2005

Hope, JC, Mense, SM, Jalakas, M, Mitsumoto, J and Freyer, GA "Rqh1 blocks recombination between sister chromatids during double strand break repair, independent of its helicase activity" Proceedings of the National Academy of Science 103, 5875-5880, 2006

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