Analysis of the 5' Flanking Region of the Rat Proliferating Cell Nuclear Antigen (PCNA) Gene

The proliferating cell nuclear antigen (PCNA), highly conserved among eukaryotes, is an auxiliary factor for DNA polymerase delta. In this report we sequenced 1560 nucleotides (nt) of the 5' flanking region of the rat PCNA gene and located the transcription initiation site. The sequence contains 1435 nt upstream of the cap site and promotes transcription of a linked heterologous reporter gene in rat, mouse and human cells. Transient expression assays using a series of 5' deletion mutants revealed that 240 nt of the upstream sequence are sufficient for full promoter activity. Three GC boxes and several other binding sites of transcription factors were observed, but neither a TATA nor a CCAAT sequence was found in this region. The results also suggested the existence of a negative regulatory element(s) between -968 and -691. Cotransfection with early region 1 (E1) genes of human adenoviruses activated the expression of the reporter gene, suggesting that an E1-responsive element is located at the proximal promoter region within 81 nt upstream of the transcription initiation site.