title: Involvement of CFTR in oviductal HCO3- secretion and its effect on soluble adenylate cyclase-dependent early embryo development.
abstract: BACKGROUND
  The cystic fibrosis transmembrane conductance regulator (CFTR) plays a critical role in electrolyte and fluid transport in epithelial cells, and women with cystic fibrosis (CF), caused by CFTR gene mutations, have a higher incidence of infertility.
  
  
  METHODS
  In the present study, we investigated the expression of CFTR in porcine oviduct and its functional role in oviductal HCO(3)(-) secretion and embryo development with RT-PCR, western blot, patch-clamp, short-circuit current (I(sc)), pH measurement and embryo culture.
  
  
  RESULTS
  RT-PCR and western blot analysis showed the expression of CFTR mRNA and protein in the oviduct with its localization demonstrated by immunohistochemistry. The whole-cell patch-clamp recording revealed a forskolin (FSK)-activated current with electrophysiological and pharmacological characteristics of CFTR. The I(sc) measurement showed that FSK-stimulated an increase in the I(sc), which could be significantly reduced by CFTR inhibitor or removal of both CO(2) and HCO(3)(-). pH measurement showed a FSK stimulated alkalization at the apical surface, which could be inhibited by CFTR inhibitor, indicating CFTR-mediated HCO(3)(-) secretion. Mouse embryo development from 2-cell to morula or blastocyst stage was significantly inhibited in the absence of HCO(3)(-) or when co-cultured with HCO(3)(-) secretion-deficient CFTR mutant cells as compared with the wild-type. RT-PCR, western blot and immunostaining showed the expression of soluble adenylate cyclase (sAC), the known HCO(3)(-) sensor, in embryos. Treatment with its inhibitors, 2-hydroxyestradiol and KH7, prevented the HCO(3)(-) dependent embryo development.
  
  
  CONCLUSIONS
  The present results suggest that CFTR-mediated oviductal HCO(3)(-) secretion may be vital for sAC-dependent early embryo development, a defect of which may contribute to the reduced fertility seen in women with CF.
authors.affiliation: School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
authors.forename: Min Hui
authors.initials: MH
authors.lastname: Chen
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhou
authors.forename: Ye Chun
authors.initials: YC
authors.lastname: Ruan
authors.forename: Hau Yan
authors.initials: HY
authors.lastname: Wong
authors.forename: Yong Chao
authors.initials: YC
authors.lastname: Lu
authors.forename: Jing Hui
authors.initials: JH
authors.lastname: Guo
authors.forename: Yiu Wa
authors.initials: YW
authors.lastname: Chung
authors.forename: Ping Bo
authors.initials: PB
authors.lastname: Huang
authors.forename: He Feng
authors.initials: HF
authors.lastname: Huang
authors.forename: Wen Liang
authors.initials: WL
authors.lastname: Zhou
authors.forename: Hsiao Chang
authors.initials: HC
authors.lastname: Chan
mesh_terms: D000262:Adenylyl Cyclases / Q000502:physiology*; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D015153:Blotting, Western; D005576:Colforsin / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004553:Electric Conductivity; D046149:Embryo Culture Techniques; D004622:Embryo, Mammalian / Q000378:metabolism*; D047108:Embryonic Development; D005187:Fallopian Tubes / Q000378:metabolism*; D005260:Female; D006863:Hydrogen-Ion Concentration; D007150:Immunohistochemistry; D051379:Mice; D018408:Patch-Clamp Techniques; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D001639:Bicarbonates; D012333:RNA, Messenger; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005576:Colforsin; D000262:Adenylyl Cyclases