The nuclear transcription factor NF-kappa B mediates interleukin-1 beta-induced expression of cyclooxygenase-2 in human myometrial cells

OBJECTIVE: Up-regulation of prostaglandin production by gestational tissues in the setting of intrauterine infection has been implicated as an importa nt contributor to preterm labor and parturition. In this study we investiga ted the possible role of the nuclear transcription factor NF-kappa B in int erleukin-1 signaling, leading to the expression of cyclooxygenase 2 and pro staglandin production in human myometrial cell cultures. STUDY DESIGN: Human myometrial smooth muscle cells from an immortalized lin e were used as a model system between passages 20 and 35. Growth-arrested c ell cultures were stimulated with human recombinant interleukin 1, and the activation of NF-kappa B was assessed by the degradation of the inhibitory protein I kappa B alpha (Western analysis), as well as by nuclear binding o f NF-kappa B by using an electrophoretic mobility shift assay. The abundanc e of cyclooxygenase-2 messenger ribonucleic acid and protein was measured b y Northern and Western analyses, whereas prostaglandin (prostaglandin I-2 a nd prostaglandin E-2) production was determined by specific radioimmunoassa ys. RESULTS: Within 15 minutes of stimulation with interleukin 1, 90% of I kapp a B-alpha was degraded. This was temporally associated with nuclear translo cation and binding of NF-kappa B. Within 30 minutes, cyclooxygenase 2 messe nger ribonucleic acid appeared, with steady-state levels increasing up to 4 hours. This was followed by an up to 80-fold increase in cyclooxygenase 2 protein and a corresponding time-dependent increase in prostaglandin produc tion. When I kappa B-alpha degradation was blocked with calpain I inhibitor , NF-kappa B translocation, cyclooxygenase 2 messenger ribonucleic acid and protein expression, and prostaglandin synthesis were also inhibited. CONCLUSION: Stimulation of human myometrial cells with interleukin 1 leads to rapid activation of the transcription factor NF-kappa B, which is functi onally linked to the expression of cyclooxygenase 2 messenger ribonucleic a cid, protein, and prostaglandin synthesis.