In somatic cells, mitosis does not occur before DNA synthesis is complete. However, this dependence can be disrupted by mutations or chemical treatments indicating that it is maintained normally by control mechanisms. These types of control mechanisms have been termed """"""""checkpoints"""""""". (1). The checkpoint coupling mitosis to completion of DNA replication ensures that cells can survive periods of S-phase arrest resulting from exposure to inhibitors of DNA synthesis or DNA damage. As such inhibitors are frequently used in chemotherapy, it is important to understand how this control works.
The specific aim of the experiments proposed here is to investigate this checkpoint using the fission yeast, Schizosaccharomyces pombe, as a model system. As the basic mechanisms controlling the cell cycle have been highly conserved during evolution, results obtained are likely to be applicable to all eukaryotic cells. Coupling of mitosis to completion of DNA replication requires an intracellular sensing pathway: proteins that control mitosis must """"""""receive"""""""" information about chromosomes. Previous work has established that the highly conserved mitotic regulator cdc2 plays a central role in this process. Other proteins known to regulate activation of cdc2 are also involved. Recently, new genes (hus and rad genes) encoding proteins acting early in the pathway have been identified. these proteins are likely to be involved in """"""""signalling"""""""" cdc2 that replication is incomplete. It is proposed to use the available mutants to determine what these """"""""signals"""""""" are and how they are """"""""detected"""""""" by cdc2 using a combination of molecular, genetic and biochemical techniques. In addition, it is proposed to identify novel gene functions that link these two processes.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM050015-03
Application #
2187596
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1993-08-01
Project End
1997-07-31
Budget Start
1995-08-01
Budget End
1996-07-31
Support Year
3
Fiscal Year
1995
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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