Urocortin II is expressed in human pregnant myometrial cells and regulates myosin light chain phosphorylation: potential role of the type-2 corticotropin-releasing hormone receptor in the control of myometrial contractility.
The family of CRH-related peptides are suggested to play important roles in the control of myometrial contractility during pregnancy and labor. In this study we investigated the expression of urocortin II (UCN II) in human myometrium and its ability to phosphorylate intracellular components that can be involved in modulating myometrial contractility. Using RT-PCR and fluorescent in situ hybridization, we demonstrated that UCN II and type-2 CRH receptor (CRH-R2) mRNAs were expressed in human nonpregnant and pregnant myometrium. Immunofluorescent studies confirmed protein expression of UCN II in human pregnant myometrial cells, whereas chemical cross-linking studies with radiolabeled UCN II confirmed the presence of CRH-R2 sites with an apparent molecular mass of 50 kDa. Treatment of primary human myometrial cells with UCN II to specifically activate CRH-R2 resulted in a dose-dependent increase of myosin light chain (MLC(20)) phosphorylation. Activation of protein kinase C (PKC) and ERK1/2 was required for the UCN II-induced activation of MLC(20), because treatment of myometrial cells with inhibitors of MAPK kinase 1 (U0126) and PKC (bisindolylmaleimide) inhibited the UCN II-induced phosphorylation of MLC(20). Furthermore, the UCN II effect on MLC(20) was dependent on RhoA translocation to the membrane and subsequent activation of RhoA-associated kinase, as shown by the use of the specific inhibitors exoenzyme C3 and Y27632. Collectively, our data suggest a distinctive role for CRH-R2- specific agonists like UCN II in the control of myometrial contractility during human pregnancy involving sequential activation of PKC, MAPK kinase 1, ERK1/2, RhoA, and RhoA-associated kinase, leading to the MLC(20) phosphorylation.
Biomedical Research Institute, Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom.
Emmanouil
E
Karteris
Edward W
EW
Hillhouse
Dimitris
D
Grammatopoulos
D000328:Adult; D003346:Corticotropin-Releasing Hormone / Q000032:analysis / Q000235:genetics* / Q000502:physiology*; D003432:Cross-Linking Reagents; D004789:Enzyme Activation; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D047908:Intracellular Signaling Peptides and Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009215:Myometrium / Q000378:metabolism*; D018994:Myosin Light Chains / Q000378:metabolism*; D010766:Phosphorylation; D011247:Pregnancy; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D018019:Receptors, Corticotropin-Releasing Hormone / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D054832:Urocortins; D014590:Uterine Contraction / Q000502:physiology*; D054460:rho-Associated Kinases
D003432:Cross-Linking Reagents; D047908:Intracellular Signaling Peptides and Proteins; D018994:Myosin Light Chains; D012333:RNA, Messenger; D018019:Receptors, Corticotropin-Releasing Hormone; D054832:Urocortins; D003346:Corticotropin-Releasing Hormone; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases