Role of Distinct Mitogen-Activated Protein Kinase Pathways and Cooperation between Ets-2, ATF-2, and Jun Family Members in Human Urokinase-Type Plasminogen Activator Gene Induction by Interleukin-1 and Tetradecanoyl Phorbol Acetate

Abstract

We have investigated the in vivo and in vitro regulation of the human urokinase-type plasminogen activator (uPA) gene by interleukin-1 (IL-1) and analyzed the transcription factors and signalling pathways involved in the response of the −2.0-kb uPA enhancer to IL-1 induction and to tetradecanoyl phorbol acetate (TPA) induction. Mutational analysis showed the cooperative activity of the Ets-binding site (EBS) and the two AP-1 elements of the enhancer. The results reveal that the EBS is required for the response to both inducers mediated by Ets-2, which is regulated at a level subsequent to DNA binding, by an IL-1- and phorbol ester-inducible transactivation domain. Both the IL-1 and the TPA-mediated induction result in a drastic increase of AP-1 binding to the downstream site of the enhancer (uPA 3′ TPA-responsive element), while a mostly qualitative change, resulting from the interplay between ATF-2 homodimers and c-Jun–ATF-2 heterodimers, takes place at the upstream AP-1 element. The analysis of two distinct mitogen-activated protein kinase pathways shows that stress-activated protein kinase–Jun N-terminal kinase activation, resulting in the phosphorylation of ATF-2, c-Jun, and JunD, is required not only for the IL-1- but also for the TPA-dependent induction, while the extracellular signal-related kinase 1 (ERK-1) and ERK-2 activation is involved in the TPA- but not in the IL-1-dependent stimulation of the uPA enhancer.

ACKNOWLEDGMENTS

We thank Diego Di Lorenzo (Civic Hospital of Brescia) for the generous gift of samples from IL-1-treated rats and those persons mentioned in the text for kindly providing us with various expression vectors. We also thank Maria Terracciano for excellent technical assistance and Luigi Lania and Andrea Riccio for critical review of the manuscript.

The work was supported by grants from the Associazione Italiana per la Ricerca sul Cancro (AIRC) to P.V. G.C. and D.V. were supported by Fellowships from CNR; L.C. and A.C. were recipients of AIRC Fellowships.

G. Cirillo and L. Casalino contributed equally to this work.