Intracellular events that follow the binding of growth factors to cellular receptors are virtually undefined at the molecular level. The identification and characterization of genes whose expression is cell cycle dependent is the first necessary step in the search for genes that actually control cell proliferation. I have isolated three cDNA clones derived from Syrian hamster sequences that hybridize to unique cytoplasmic RNAs induced which quiescent cells are stimulated to proliferate. Although the biological function of these G1-specific sequences is presently unknown, their role in cell cycle progression is supported by their similarities with several oncogenes implicated in cell growth. An intriguing relationship to human malignancy is suggested by elevated levels of these sequences in some human leukemias. The transcriptional or post-transcriptional processes responsible for the transient increase in cytoplasmic RNA of three specific G1-sequences will be determined. At different times following stimulation of serum-deprived cells, the rate of transcription, the levels of nuclear and cytoplasmic RNA, and the stability of mRNA will be determined. The level of expression of these three specific RNAs in a variety of differentiation arrested human leukemias will be correlated to a number of well defined characteristics specific for each type of leukemia to evaluate the role of these sequences in malignancy. To pursue studies in potential biochemical function, full-length cDNA clones corresponding to these three G1-specific sequences will be isolated, restriction mapped and sequenced. Sequence comparisons to a data base will reveal if any homologies exist to previously sequenced genes. Using the cDNA, Syrian hamster genomic clones corresponding to these three RNA sequences will be identified, isolated, and their transcriptional organization analyzed. Putative regulatory regions will be sequenced and comparisons will be performed to identify consensus regions for future studies. The completion of these studies sets the stage for future studies concerning the definition of the biological activities of these G1-specific sequences and their role in the control of normal and abnormal cell growth.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA043798-02
Application #
3186157
Study Section
Molecular Biology Study Section (MBY)
Project Start
1986-12-01
Project End
1989-11-30
Budget Start
1987-12-01
Budget End
1988-11-30
Support Year
2
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of Kentucky
Department
Type
Schools of Arts and Sciences
DUNS #
832127323
City
Lexington
State
KY
Country
United States
Zip Code
40506
Hirschhorn, R R (1994) Gene expression in a temperature-sensitive mutant of the cell cycle. SAAS Bull Biochem Biotechnol 7:31-5
Wolf, J R; Hu, Y; Hirschhorn, R R et al. (1993) MyoD and regulation of prostaglandin H synthase. Exp Cell Res 207:439-41
Wolf, J R; Hirschhorn, R R; Steiner, S M (1992) Growth factor responsiveness: role of MyoD and myogenin. Exp Cell Res 202:105-12
Hirschhorn, R R (1992) Serum-inducible gene expression in fibroblasts. SAAS Bull Biochem Biotechnol 5:26-9
Ferrier, A F; Hirschhorn, R R (1992) Growth-regulated expression of vimentin in hamster fibroblasts is a result of increased transcription. J Cell Biochem 50:245-54
Rossi, A M; Hirschhorn, R R (1991) Expression of growth-regulated genes in normal and SV40 transformed hamster fibroblasts. J Cell Biochem 47:165-73
Steiner, S M; Keutzer, J C; Hirschhorn, R R (1991) Prostaglandin endoperoxide synthase (cyclooxygenase) mRNA and protein production in mouse myoblasts and a differentiation-defective variant. Exp Cell Res 192:643-6
Keutzer, J C; Hirschhorn, R R (1990) The growth-regulated gene 1B6 is identified as the heavy chain of calpactin I. Exp Cell Res 188:153-9