To investigate the process involved in the production of and responsiveness to interleukin 1beta (IL-1beta) in synovial fibroblast-like cells, we analyzed the enhancer region of pro-IL-1beta gene in a cell clone, E11, established from a patient with rheumatoid arthritis (RA).
A cell clone, E11, was derived from rheumatoid synovial fibroblast-like cells transformed with simian virus 40 large T antigen expression vector by electroporation. Responsiveness of E11 to IL-1beta was analyzed by [3H] thymidine incorporation and Northern blotting. IL-1beta responsive elements on pro-IL-1beta gene were analyzed by chloramphenicol acetyltransferase analysis.
E11 resembled synovial fibroblasts based on morphological characteristics and phenotypic analysis. It also demonstrated marked enhancement of proliferation and rapid induction of IL-1beta mRNA expression by IL-1beta. We also identified IL-1beta responsive elements on the pro-IL-1beta gene at a position between -3134 and -3092 that contains the AP-1 binding site and between -2782 and -2729, which includes both AP-1 and nuclear factor-kappaB (NF-kappaB) binding sites.
AP-1 and NF-kappaB binding elements were required for transcriptional regulation of the IL-1beta gene in the autocrine growth system of RA synovial cells.