title: CRH activation of different signaling pathways results in differential calcium signaling in human pregnant myometrium before and during labor.
abstract: BACKGROUND
  Our previous study has demonstrated that CRH has differential effects on human uterine contractility before and after onset of labor. Intracellular Ca2+ concentration ([Ca2+]i) mobilization plays an important role in the control of uterine contraction.
  
  
  OBJECTIVE
  Our objective was to investigate the effects of CRH on [Ca2+]i homeostasis in laboring and nonlaboring myometrial cells and determine subsequent signaling involved in [Ca2+]i regulation by CRH.
  
  
  METHODS
  The myometrial tissues were obtained from pregnant women who were undergoing or not undergoing labor at term. [Ca2+]i was determined by Ca2+ imaging system using the fluorescent dye fura-2-acetoxymethyl ester. Western blot analysis, ELISA, and RIA were used to determine the signaling pathways induced by CRH.
  
  
  RESULTS
  CRH induced Ca2+ transient in laboring cells, which was blocked by CRH receptor type 1 (CRHR1) antagonist antalarmin. CRHR1 knockdown impaired this effect of CRH. CRH activated Gi protein, decreased cAMP production, and induced phosphorylated phospholipase C-β3 and inositol-1,4,5-triphosphate production. Phospholipase C and inositol-1,4,5-triphosphate receptor inhibitors blocked the CRH-induced Ca2+ transient in laboring cells. CRH did not induce whereas antalarmin induced the Ca2+ transient in nonlaboring cells. Knockdown of CRHR1 impaired the effect of antalarmin. CRH acted on CRHR1 to activate Gs in nonlaboring cells. Forskolin blocked antalarmin-induced Ca2+ transient.
  
  
  CONCLUSIONS
  CRH acts on CRHR1 to activate different signaling pathways before and after onset of labor, thereby resulting in differential calcium signaling in response to CRH. The signaling pathways of CRHR1 might serve as a target for the development of new therapeutic strategies for preterm birth.
authors.affiliation: Department of Physiology, Second Military Medical University, and Department of Obsetrics and Gynecology, Changhai Hospital, 800 Xiangyin Road, Shanghai 200433, PR China.
authors.forename: Xingji
authors.initials: X
authors.lastname: You
authors.forename: Lu
authors.initials: L
authors.lastname: Gao
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Chen
authors.initials: C
authors.lastname: Xu
authors.forename: Chunmin
authors.initials: C
authors.lastname: Liu
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.forename: Ning
authors.initials: N
authors.lastname: Hui
authors.forename: Hang
authors.initials: H
authors.lastname: Gu
authors.forename: Xin
authors.initials: X
authors.lastname: Ni
mesh_terms: D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D002478:Cells, Cultured; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007743:Labor, Obstetric / Q000378:metabolism*; D009215:Myometrium / Q000166:cytology / Q000378:metabolism*; D011247:Pregnancy; D047928:Premature Birth / Q000378:metabolism; D018019:Receptors, Corticotropin-Releasing Hormone / Q000037:antagonists & inhibitors / Q000378:metabolism; D014590:Uterine Contraction / Q000502:physiology*; D000099052:CRF Receptor, Type 1
chemical_list: D005456:Fluorescent Dyes; D018019:Receptors, Corticotropin-Releasing Hormone; C049925:fura-2-am; D000099052:CRF Receptor, Type 1; D003346:Corticotropin-Releasing Hormone; D000242:Cyclic AMP; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D019205:GTP-Binding Protein alpha Subunits, Gs; D002118:Calcium; D016257:Fura-2