Association of Pur alpha and E2F-1 suppresses transcriptional activity of E2F-1.
Protein-protein interaction can play an important role in the control of several biological events including gene transcription, replication and cell proliferation. E2F-1 is a DNA-binding transcription factor which, upon interaction with its target DNA sequence, induces expression of several S phase specific genes allowing progression of the cell cycle. Evidently, ... the activity of this protein is modulated by its cellular partner, pRb, which in the hypophosphorylated form, binds to E2F-1 and inactivates its transcriptional ability. In this study, we have demonstrated that expression of a sequence-specific single-stranded DNA binding protein, Pur alpha, in cells decreases the ability of E2F-1 to exert its transcriptional activity upon the responsive promoter derived from DHFR. Results from band shift experiments revealed that while Pur alpha does not recognize the double-stranded DNA fragment containing the E2F-1 binding site, it has the ability to inhibit E2F-1 interaction with its target DNA sequence. Results from GST pull-down assays and the combined immunoprecipitation/Western blot analysis of nuclear extracts revealed a direct association of E2F-1 with Pur alpha in the absence of the DNA molecule containing the E2F-1 binding site. The association of Pur alpha with E2F-1 may increase the stability of E2F-1, as a higher level of E2F-1 was detected in cells coexpressing Pur alpha and E2F-1. The importance of these observations with respect to the role of Pur alpha in the control of cell cycle progression is discussed.
Mesh Terms:
Astrocytes, Binding Sites, Carrier Proteins, Cell Cycle, Cell Cycle Proteins, Cell Line, Cell-Free System, Consensus Sequence, Cyclic AMP Response Element-Binding Protein, DNA, Single-Stranded, DNA-Binding Proteins, E2F Transcription Factors, E2F1 Transcription Factor, Genes, Reporter, Humans, Promoter Regions, Genetic, Protein Binding, Recombinant Fusion Proteins, Retinoblastoma Protein, Retinoblastoma-Binding Protein 1, S Phase, Tetrahydrofolate Dehydrogenase, Transcription Factor DP1, Transcription Factors, Transcription, Genetic, Transfection
Astrocytes, Binding Sites, Carrier Proteins, Cell Cycle, Cell Cycle Proteins, Cell Line, Cell-Free System, Consensus Sequence, Cyclic AMP Response Element-Binding Protein, DNA, Single-Stranded, DNA-Binding Proteins, E2F Transcription Factors, E2F1 Transcription Factor, Genes, Reporter, Humans, Promoter Regions, Genetic, Protein Binding, Recombinant Fusion Proteins, Retinoblastoma Protein, Retinoblastoma-Binding Protein 1, S Phase, Tetrahydrofolate Dehydrogenase, Transcription Factor DP1, Transcription Factors, Transcription, Genetic, Transfection
Oncogene
Date: Nov. 04, 1999
PubMed ID: 10597240
View in: Pubmed Google Scholar
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