Distinct roles for Sp1 and E2F sites in the growth/cell cycle regulation of the DHFR promoter

David E. Jensen, Adrian R. Black, Andrew G. Swick, Jane Clifford Azizkhan

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

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 languageEnglish (US)
Pages (from-to)24-31
Number of pages8
JournalJournal of Cellular Biochemistry
Volume67
Issue number1
DOIs
StatePublished - Oct 1 1997

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

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