PROMOTER ACTIVITY OF THE PROLIFERATING-CELL NUCLEAR ANTIGEN GENE IS ASSOCIATED WITH INDUCIBLE CRE-BINDING PROTEINS IN INTERLEUKIN 2-STIMULATED T-LYMPHOCYTES

The proliferating-cell nuclear antigen (PCNA) gene encodes an auxiliar y factor of DNA polymerase delta and functions in DNA replication duri ng S phase. It is expressed at much higher levels in proliferating cel ls than in quiescent cells. We have studied the regulatory role of the 5'-flanking sequence of the murine PCNA gene in interleukin 2 (IL-2)- responsive cloned T cells (L2). Analysis of a set of deletion construc ts in transient transfection assays measuring heterologous reporter ge ne (luciferase) activity demonstrated that the 182-bp 5'-flanking regi on provides full promoter activity in IL-2-stimulated L2 cells. While many elements contribute to PCNA promoter strength in IL-2-stimulated cells, the largest decrease in activity occurred with deletion of the tandem CRE (cyclic AMP response element) binding sites located at nucl eotides -37 to -52. With a gel mobility shift assay, several IL-2-indu cible DNA-protein complexes were detected, including CREB (CRE-binding ) and ATF1 (activating transcription factor) proteins that are specifi c for the PCNA-CRE sequence. Methylation interference analysis confirm ed specific binding of these proteins to the CRE sites. Mutation at th e PCNA-CRE motif abolishes IL-2-inducibile binding and reduces substan tially PCNA promoter activity. These results indicate that IL-2-stimul ated PCNA transcription may be partially mediated by these CRE-binding proteins.