Abstract
Dihydrofolate reductase activity is required for many biosynthetic pathways including nucleotide synthesis. Its expression is therefore central to cellular growth, and it has become a key target for cancer chemotherapy. Transcription of the dihydrofolate reductase gene is regulated with growth, being expressed maximally in late G1/early S phase following serum stimulation of quiescent cells. This regulation is directed by a promoter which contains binding sites for only the transcription factors Sp1 and E2F. In this study, the role of these promoter elements in growth/cell cycle regulation of dihydrofolate transcription was addressed directly by transient transfection of Balb/c 3T3 cells with mutant promoter-reporter gene constructs. The E2F sites were found to repress transcription in G0 and early G1 but did not contribute to the level of transcription in late G1/S phase. In contrast, Sp1 sites were able to mediate induction of transcription from the dihydrofolate reductase promoter, as well as a heterologous promoter, following serum stimulation of quiescent cells. These findings add dihydrofolate reductase to a growing list of genes at which E2F sites are primarily repressive elements and delineate a role for Sp1 sites in the growth/cell cycle regulation of transcription.
Original language | English (US) |
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Pages (from-to) | 24-31 |
Number of pages | 8 |
Journal | Journal of Cellular Biochemistry |
Volume | 67 |
Issue number | 1 |
DOIs | |
State | Published - Oct 1 1997 |
Externally published | Yes |
Keywords
- Balb/c 3T3 cells
- Dihydrofolate reductase
- Gene expression
- Growth control
- Repression
- Retinoblastoma
- TATAA-less promoter
- Transcription
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology