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Cytokine-initiated signal transduction in human myometrial cells
F Hertelendy1, R Romero, M Molnár
1Department of Obstetrics and Gynecology, St. Louis University School of Medicine, MO 63110-0250.
Problem:
The objectives of this study were to evaluate interleukin-1 (IL-1) binding and some postreceptor actions of this cytokine and tumor necrosis factor (TNF) in human myometrial cells (HMC).
Method:
Monolayer cultures of HMC were used to characterize binding and to measure cyclic (c)AMP, prostaglandin (PG)E2, and PGI2 production. Membrane preparations were used to assess ADP-ribosylation and for immunoblotting.
Results:
HMC were found to specifically bind [125I]IL-1 with an apparent Kd of 2 x 10(-10) M. Incubation of HMC with IL-1 or TNF caused a time-dependent and dose-dependent accumulation of cAMP, as well as a significant potentiation of forskolin-promoted cAMP production. These cytokines also increase PGE2 and PGI2 output, independently of the activation of adenylyl cyclase. IL-1 treatment had no measurable effect either on cholera toxin-mediated and pertussis toxin-mediated ADP-ribosylation, or on the amount of Gi proteins, as assessed by immunoblotting using a polyclonal antibody.
Conclusions:
It is suggested that IL-1 and TNF may activate one or more isoforms of the catalytic component of adenylyl cyclase, raising intracellular cAMP.