title: Lubiprostone targets prostanoid signaling and promotes ion transporter trafficking, mucus exocytosis, and contractility.
abstract: OBJECTIVE
  Lubiprostone is a chloride channel activator in clinical use for the treatment of chronic constipation, but the mechanisms of action of the drug are poorly understood. The aim of this study was to determine whether lubiprostone exerts secretory effects in the intestine by membrane trafficking of ion transporters and associated machinery.
  
  
  METHODS
  Immunolabeling and quantitative fluorescence intensity were used to examine lubiprostone-induced trafficking of the cystic fibrosis transmembrane conductance regulator (CFTR), sodium/potassium-coupled chloride co-transporter 1 (NKCC1), electrogenic sodium/bicarbonate co-transporter 1 (NBCe1), down-regulated in adenoma (DRA), putative anion transporter 1 (PAT1), sodium/proton exchanger 3 (NHE3), Ca(2+) activated chloride channel 2 (ClC-2) serotonin and its transporter SERT, E prostanoid receptors EP4 and EP1, sodium/potassium ATPase (Na-K-ATPase) and protein kinase A (PKA). The effects of lubiprostone on mucus exocytosis in rat intestine and human rectosigmoid explants were also examined.
  
  
  RESULTS
  Lubiprostone induced contraction of villi and proximal colonic plicae and membrane trafficking of transporters that was more pronounced in villus/surface cells compared to the crypt. Membrane trafficking was determined by: (1) increased membrane labeling for CFTR, PAT1, NKCC1, and NBCe1 and decreased membrane labeling for NHE3, DRA and ClC-2; (2) increased serotonin, SERT, EP4, EP1 and PKA labeling in enterochromaffin cells; (3) increased SERT, EP4, EP1, PKA and Na-K-ATPase in enterocytes; and (4) increased mucus exocytosis in goblet cells.
  
  
  CONCLUSIONS
  These data suggest that lubiprostone can target serotonergic, EP4/PKA and EP1 signaling in surface/villus regions; stimulate membrane trafficking of CFTR/NBCe1/NKCC1 in villus epithelia and PAT1/NBCe1/NKCC1 in colonic surface epithelia; suppress NHE3/DRA trafficking and fluid absorption; and enhance mucus-mobilization and mucosal contractility.
authors.affiliation: Department of Pediatrics/Gastroenterology and Hepatology, Yale University School of Medicine, 333 Cedar St, FMP 408, P.O. Box 208064, New Haven, CT 06520, USA. robert.jakab@yale.edu
authors.forename: Robert L
authors.initials: RL
authors.lastname: Jakab
authors.forename: Anne M
authors.initials: AM
authors.lastname: Collaco
authors.forename: Nadia A
authors.initials: NA
authors.lastname: Ameen
mesh_terms: D000527:Alprostadil / Q000031:analogs & derivatives* / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D017920:Antiporters / Q000378:metabolism; D001706:Biopsy; D000090007:CLC-2 Chloride Channels; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism; D005089:Exocytosis / Q000187:drug effects*; D005455:Fluorescent Antibody Technique; D006801:Humans; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism*; D017136:Ion Transport; D000068238:Lubiprostone; D026901:Membrane Transport Proteins / Q000378:metabolism; D009093:Mucus / Q000187:drug effects* / Q000378:metabolism*; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism*; D027361:Organic Anion Transporters / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D058306:Receptors, Prostaglandin E, EP1 Subtype / Q000378:metabolism; D058309:Receptors, Prostaglandin E, EP4 Subtype / Q000378:metabolism; D027982:Sodium-Bicarbonate Symporters / Q000378:metabolism; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D028021:Sodium-Potassium-Chloride Symporters / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D000076988:Sulfate Transporters
chemical_list: D017920:Antiporters; D000090007:CLC-2 Chloride Channels; C000715429:Clcn2 protein, rat; D026901:Membrane Transport Proteins; D027361:Organic Anion Transporters; D016601:RNA-Binding Proteins; D058306:Receptors, Prostaglandin E, EP1 Subtype; D058309:Receptors, Prostaglandin E, EP4 Subtype; C439529:SLC26A6 protein, human; C000613385:SLC9A3 protein, human; C482440:Sert1 protein, rat; C489861:Slc26a3 protein, rat; C422004:Slc4a4 protein, rat; C000613387:Slc9a3 protein, rat; D027982:Sodium-Bicarbonate Symporters; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; D028021:Sodium-Potassium-Chloride Symporters; D000076988:Sulfate Transporters; C515964:citrate-isocitrate carrier, rat; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000068238:Lubiprostone; D017868:Cyclic AMP-Dependent Protein Kinases; D000254:Sodium-Potassium-Exchanging ATPase; D000527:Alprostadil