Chromosomes are particularly vulnerable to genetic damage while they are being replicated. If DNA is damaged, or if there are not enough nucleotides, the process of replication is halted while problems are corrected. This is unlikely to be due to a physical block to DNA replication, rather complex mechanisms involving cell cycle control and DNA repair ensure that S-phase arrest and recovery take place in an orderly fashion. By preventing genetic changes during replication, the mechanisms underlying S-phase arrest and recovery play an important role in preventing cancer. Moreover, since inhibitors of S-phase are frequently used in chemotherapy, understanding the cellular basis of S-phase arrest and recovery is of considerable health relevance. We have been studying 5-phase arrest and recovery using the fission yeast, Schizosaccharomyces pombe. Like the more commonly studied yeast, Saccharomyces cerevisiae, S. pombe can be conveniently studied using a range of powerful molecular and genetic techniques. We have identified mutants that have defects in 5-phase arrest and recovery by screening for mutants that undergo abnormal mitoses upon treatment with hydroxyurea (HU), an inhibitor DNA synthesis. Two of the genes we have identified are related to human genes mutated in cancer-prone syndromes. Rad3+ is required for S-phase arrest and is related to the ATM gene, deficient in patients suffering from Ataxia-Telangiectasia (A-T). hus2+ is required for recovery from S-phase arrest and is related to BLM, the gene mutated in patients afflicted with Blooms Syndrome (BS). A-T and BS patients display a range of complex symptoms, including a significantly increased risk for a range of cancers. To better understand the cellular processes preventing cancer, we are proposing to analyze rad3+, hus2+ and other genes required for S- phase arrest and recovery.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM050015-05
Application #
2397630
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1993-08-01
Project End
2001-07-31
Budget Start
1997-08-01
Budget End
1998-07-31
Support Year
5
Fiscal Year
1997
Total Cost
Indirect Cost
Name
Harvard University
Department
Genetics
Type
Schools of Medicine
DUNS #
082359691
City
Boston
State
MA
Country
United States
Zip Code
02115
Wolkow, Tom D; Enoch, Tamar (2003) Fission yeast Rad26 responds to DNA damage independently of Rad3. BMC Genet 4:6
Wolkow, Tom D; Enoch, Tamar (2002) Fission yeast Rad26 is a regulatory subunit of the Rad3 checkpoint kinase. Mol Biol Cell 13:480-92
Kaur, R; Kostrub, C F; Enoch, T (2001) Structure-function analysis of fission yeast Hus1-Rad1-Rad9 checkpoint complex. Mol Biol Cell 12:3744-58
Weiss, R S; Enoch, T; Leder, P (2000) Inactivation of mouse Hus1 results in genomic instability and impaired responses to genotoxic stress. Genes Dev 14:1886-98
Chapman, C R; Evans, S T; Carr, A M et al. (1999) Requirement of sequences outside the conserved kinase domain of fission yeast Rad3p for checkpoint control. Mol Biol Cell 10:3223-38
Weiss, R S; Kostrub, C F; Enoch, T et al. (1999) Mouse Hus1, a homolog of the Schizosaccharomyces pombe hus1+ cell cycle checkpoint gene. Genomics 59:32-9
Moynihan, E B; Enoch, T (1999) Liz1p, a novel fission yeast membrane protein, is required for normal cell division when ribonucleotide reductase is inhibited. Mol Biol Cell 10:245-57
Kostrub, C F; Knudsen, K; Subramani, S et al. (1998) Hus1p, a conserved fission yeast checkpoint protein, interacts with Rad1p and is phosphorylated in response to DNA damage. EMBO J 17:2055-66
Forbes, K C; Humphrey, T; Enoch, T (1998) Suppressors of cdc25p overexpression identify two pathways that influence the G2/M checkpoint in fission yeast. Genetics 150:1361-75
Kostrub, C F; Lei, E P; Enoch, T (1998) Use of gap repair in fission yeast to obtain novel alleles of specific genes. Nucleic Acids Res 26:4783-4

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