Regulation of interleukin (IL)-1beta gene transcription induced by IL-1beta in rheumatoid synovial fibroblast-like cells, E11, transformed with simian virus 40 large T antigen.

Objective: 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).

Methods: 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.

Results: 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.

Conclusion: 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.