title: Prolonged treatment of cells with genistein modulates the expression and function of the cystic fibrosis transmembrane conductance regulator.
abstract: OBJECTIVE
  Cystic fibrosis (CF) is caused by dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel. In the search for new CF therapies, small molecules have been identified that rescue the defective channel gating of CF mutants (termed CFTR potentiators). Here, we investigate the long-term effects of genistein, the best-studied CFTR potentiator, on the expression and function of CFTR.
  
  
  METHODS
  We pre-treated baby hamster kidney (BHK) cells expressing wild-type or F508del-CFTR (the most common CF mutant) with concentrations of genistein that potentiate (30 microM) or inhibit (100 microM) CFTR function for 2 or 24 h at 37 degrees C before examining CFTR maturation, expression and single-channel activity.
  
  
  RESULTS
  Using the iodide efflux technique, we found that genistein pre-treatment failed to restore function to F508del-CFTR, but altered that of wild-type CFTR. Pre-treatment of cells with genistein for 2 h had little effect on CFTR processing, whereas pre-treatment for 24 h either augmented (30 microM genistein) or impaired (100 microM genistein) CFTR maturation. Using immunocytochemistry, we found that all genistein pre-treatments increased the localization of CFTR protein to the cell surface. However, following the incubation of cells with genistein (100 microM) for 2 h, individual CFTR Cl(-) channels exhibited characteristics of channel block upon channel activation.
  
  
  CONCLUSIONS
  Genistein pre-treatment alters the maturation, cell surface expression and single-channel function of CFTR in ways distinct from its acute effects. Thus, CFTR potentiators have the potential to influence CFTR by mechanisms distinct from their effects on channel gating.
authors.affiliation: Centre of Human Genetics, National Institute of Health, Lisboa, Portugal.
authors.forename: A
authors.initials: A
authors.lastname: Schmidt
authors.forename: L K
authors.initials: LK
authors.lastname: Hughes
authors.forename: Z
authors.initials: Z
authors.lastname: Cai
authors.forename: F
authors.initials: F
authors.lastname: Mendes
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.forename: D N
authors.initials: DN
authors.lastname: Sheppard
authors.forename: M D
authors.initials: MD
authors.lastname: Amaral
mesh_terms: D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D019833:Genistein / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D007150:Immunohistochemistry; D007454:Iodides / Q000378:metabolism; D015640:Ion Channel Gating / Q000187:drug effects; D007668:Kidney; D021381:Protein Transport / Q000187:drug effects; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D007454:Iodides; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D019833:Genistein