IDENTIFICATION OF AN ESSENTIAL CIS-ELEMENT NEAR THE TRANSCRIPTION START SITE FOR TRANSCRIPTIONAL ACTIVATION OF THE PROLIFERATING CELL NUCLEAR ANTIGEN GENE

Interleukin 2 (IL-2) stimulates T lymphocyte proliferation and induces the expression of proliferating cell nuclear antigen (PCNA), a proces sivity factor for DNA polymerase delta. Previously, deletion analysis suggested cis-element(s) in the proximal region of the PCNA promoter ( -40 to +143) are required for IL-2 induction in cloned T lymphocytes. The sequence 5'-TTGCGGGC-3' located at +10 to +17 is similar to the E2 F consensus binding site and is required for optimal PCNA promoter act ivity. In IL-2-stimulated T cells, nuclear proteins are induced to bin d to this sequence as demonstrated using electrophoretic mobility shif t assay (EMSA), competition EMSA, and methylation interference analysi s. A 180-kDa polypeptide was detected by UV cross-linking to bind spec ifically to the PCNA E2F-like sequence. Our data indicate that the pro tein bound to the PCNA E2F-like site is not one of the transcription f actor E2F proteins. Our results demonstrate that the E2F-like sequence and the protein(s) binding to it are required for optimal PCNA promot er activity and IL-2 induction of PCNA expression.