Protein synthesis is required for a cell to recover from radiation- induced G2-arrest. It is the purpose of this investigation to determine the nature and functions of the protein(s) involved. Two lines of inquiry will be followed. The first is prompted by the observation that an arrested cell can be brought into a mitosis- like state by fusion with a mitotic cell. This process is believed to be mediated by the donation of a group of polypeptides termed Maturation Promoting Factors (MPF), thus it is suggested that recovery from radiation-induced G2-arrest may require MPF synthesis. The second approach is prompted by the observation that arrested cells may be brought into mitosis without protein synthesis by treatment with caffeine and cycloheximide. This suggests that the components of the progression """"""""machinery"""""""" are actually intact in arrested cells (including MPF), but are inactivated. The proteins normally required for recovery must then be produced for some other activity, not directly related to progression, and probably unique to, overly abundant in, or characterized by enhanced synthesis in irradiated cells compared to age-equivalent controls. MPF will be isolated from arrested cells obtained by centrifugal elutriation and assayed for activity in Xenopus laevis oocytes. Protein synthesis in arrested cells will be monitored by incorporation of isotope-labelled amino acids, then the cells retrieved from arrest as a discrete population by caffeine treatment and mitotic cell selection. Specific polypeptides will be identified by 2-D gel electrophoresis. The work proposed is intended to determine the requirements for progression past the X-ray transition point. Such information may help us to understand why cell sensitivity to killing by irradiation increases so markedly at the X-ray transition point and may provide the means to manipulate both cell progression and cell radiosensitivity, both factors of importance to the treatment of cancer by radiation.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA040245-06
Application #
3179941
Study Section
Radiation Study Section (RAD)
Project Start
1985-01-15
Project End
1992-06-30
Budget Start
1990-07-01
Budget End
1992-06-30
Support Year
6
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of Utah
Department
Type
Schools of Medicine
DUNS #
City
Salt Lake City
State
UT
Country
United States
Zip Code
84112
Rowley, R; Zhang, J (1999) Caffeine-mediated override of checkpoint controls. A requirement for rhp6 (Schizosaccharomyces pombe). Genetics 152:61-71
Jimenez, G; Yucel, J; Rowley, R et al. (1992) The rad3+ gene of Schizosaccharomyces pombe is involved in multiple checkpoint functions and in DNA repair. Proc Natl Acad Sci U S A 89:4952-6
Rowley, R (1992) Radiation-induced mitotic delay: a genetic characterization in the fission yeast. Radiat Res 132:144-52
Rowley, R (1992) Reduction of radiation-induced G2 arrest by caffeine. Radiat Res 129:224-7
Rowley, R; Subramani, S; Young, P G (1992) Checkpoint controls in Schizosaccharomyces pombe: rad1. EMBO J 11:1335-42
Feilotter, H; Lingner, C; Rowley, R et al. (1992) Regulation of the G2-mitosis transition. Biochem Cell Biol 70:954-71
Hudson, J D; Feilotter, H; Lingner, C et al. (1991) stf1: a new suppressor of the mitotic control gene, cdc25, in Schizosaccharomyces pombe. Cold Spring Harb Symp Quant Biol 56:599-604
Rowley, R (1990) Repair of radiation-induced chromatid aberrations: relationship to G2 arrest in CHO cells. Int J Radiat Biol 58:489-98
Rowley, R; Kort, L (1989) Novobiocin, nalidixic acid, etoposide, and 4'-(9-acridinylamino)methanesulfon-m-anisidide effects on G2 and mitotic Chinese hamster ovary cell progression. Cancer Res 49:4752-7
Rowley, R; Egger, M J (1988) Method for probing cells in radiation-induced G2 arrest: demonstration of potentially lethal damage repair. Cell Tissue Kinet 21:395-403

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