title: Cyclic AMP increases COX-2 expression via mitogen-activated kinase in human myometrial cells.
abstract: Cyclic AMP (cAMP) is the archetypal smooth muscle relaxant, mediating the effects of many hormones and drugs. However, recently PGI(2) , acting via cAMP/PKA, was found to increase contraction-associated protein expression in myometrial cells and to promote oxytocin-driven myometrial contractility. Cyclo-oxygenase-2 (COX-2) is the rate-limiting enzyme in prostaglandin synthesis, which is critical to the onset and progression of human labour. We have investigated the impact of cAMP on myometrial COX-2 expression, synthesis and activity. Three cAMP agonists (8-bromo-cAMP, forskolin and rolipram) increased COX-2 mRNA expression and further studies confirmed that this was associated with COX-2 protein synthesis and activity (increased PGE(2)  and PGI(2)  in culture supernatant) in primary cultures of human myometrial cells. These effects were neither reproduced by specific agonists nor inhibited by specific inhibitors of known cAMP-effectors (PKA, EPAC and AMPK). We then used shRNA to knockdown the same effectors and another recently described cAMP-effector PDZ-GEF(1-2) , without changing the response to cAMP. We found that MAPK activation mediated the cAMP effects on COX-2 expression and that PGE(2)  acts through EP-2 to activate MAPK and increase COX-2. These data provide further evidence in support of a dual role for cAMP in the regulation of myometrial function.
authors.affiliation: Academic Department of Obstetrics & Gynaecology, Imperial College School of Medicine, Chelsea and Westminster Hospital, London, UK.
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.forename: Suren R
authors.initials: SR
authors.lastname: Sooranna
authors.forename: Kaiyu
authors.initials: K
authors.lastname: Lei
authors.forename: Mandeep
authors.initials: M
authors.lastname: Kandola
authors.forename: Phillip R
authors.initials: PR
authors.lastname: Bennett
authors.forename: Zhiqing
authors.initials: Z
authors.lastname: Liang
authors.forename: Dimitri
authors.initials: D
authors.lastname: Grammatopoulos
authors.forename: Mark R
authors.initials: MR
authors.lastname: Johnson
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000819:agonists / Q000378:metabolism; D002478:Cells, Cultured; D005576:Colforsin / Q000819:agonists / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism*; D051546:Cyclooxygenase 2 / Q000235:genetics* / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009215:Myometrium / Q000166:cytology* / Q000378:metabolism; D010766:Phosphorylation; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D020889:Rolipram / Q000819:agonists / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D034741:RNA, Small Interfering; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000242:Cyclic AMP; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D020928:Mitogen-Activated Protein Kinases; D020889:Rolipram; D015232:Dinoprostone