Interleukin-1β-induced prostaglandin E2 production in human myometrial cells:: Role of a pertussis toxin-sensitive component

PROBLEM: The objective of this study was to evaluate the possible role of pertussis toxin (PTX)-sensitive G-protein(s) in interleukin-1 beta (IL-1) signaling in human myometrial cells (HMC). METHOD: Primary cultures of HMC were stimulated with human recombinant IL-1 alone or in combination with PTX. Prostaglandin (PG) E, in the medium was measured by radioimmunoassay, cyclooxygenase type 2 (Cox-2) and I kappaB by western analysis, and the activities of two members of the mitogen-activated protein kinase (MAPK) family of enzymes, ERK-2 and JNK, by the phosphorylation of appropriate substrates. RESULTS: IL-1 increased PGE, output during an 18-hr long incubation by 21.7-fold (n = 5 experiments). This increase was inhibited by 57% after pretreatment overnight with PTX. IL-1-induced expression of Cox-2 protein was also suppressed to a similar degree in PTX-treated HMC cultures. Degradation of the nuclear factor kappa B (NF-kappaB)-inhibiting protein (I kappaB), a critical step in IL-1 signaling to the nucleus, was significantly inhibited by PTX, as was IL-1-induced activation of ERK-2 and JNK. CONCLUSIONS: It is suggested that the occupied IL-1 receptor-generated signal in HMC is transmitted by multiple pathways. One is coupled to a PTX-sensitive G-protein upstream from the MAPK phosphorylation cascade. This, in turn, may interact with another signaling pathway, the activation of NF-KB, via the phosphorylation of the I kappaB kinase complex.