title: L-arginine uptake by cationic amino acid transporter 2 is essential for colonic epithelial cell restitution.
abstract: Restoration of the colonic epithelial barrier is an important response during colitis. L-arginine (L-Arg) is a semiessential amino acid that reduces murine colitis induced by Citrobacter rodentium. Cationic amino acid transporter (CAT) proteins increase L-Arg uptake into cells. L-Arg is utilized to produce nitric oxide (NO), by inducible NO synthase (iNOS), or L-ornithine (L-Orn) by arginase (Arg) enzymes. The latter is followed by generation of polyamines by ornithine decarboxylase (ODC) and L-proline (L-Pro) by ornithine aminotransferase (OAT). We show that L-Arg enhanced epithelial restitution in conditionally immortalized young adult mouse colon (YAMC) cells in a wound repair model, and in isolated mouse colonic epithelial cells (CECs), using a cell migration assay. Restitution was impaired by C. rodentium. Wounding induced CAT2, and inhibition of L-Arg uptake by the competitive inhibitor L-lysine (L-Lys) or by CAT2 shRNA, but not CAT1 shRNA, decreased restitution. Migration was impaired in CECs treated with L-Lys or from CAT2(-/-) mice. Wounding increased Arg1 expression, and inhibition of arginase with S-(2-boronoethyl)-L-cysteine (BEC) or Arg1 shRNA inhibited restitution in YAMC cells; cell migration in CECs was also impaired by BEC. Inhibition of ODC or iNOS did not alter restitution. L-Orn or L-Pro restored restitution in cells treated with BEC or Arg1 shRNA, whereas the polyamine putrescine had no benefit. Wounding increased OAT levels, OAT shRNA inhibited restitution, and L-Pro restored restitution in cells with OAT knockdown. Uptake of L-Arg, and its metabolism by Arg1 to L-Orn and conversion to L-Pro by OAT is essential for colonic epithelial wound repair.
authors.affiliation: Department of Medicine, Division of Gastroenterology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
authors.forename: Kshipra
authors.initials: K
authors.lastname: Singh
authors.forename: Lori A
authors.initials: LA
authors.lastname: Coburn
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Barry
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Boucher
authors.forename: Rupesh
authors.initials: R
authors.lastname: Chaturvedi
authors.forename: Keith T
authors.initials: KT
authors.lastname: Wilson
mesh_terms: D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D027202:Cationic Amino Acid Transporter 2 / Q000378:metabolism*; D003092:Colitis / Q000188:drug therapy* / Q000378:metabolism*; D003106:Colon; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL
chemical_list: D027202:Cationic Amino Acid Transporter 2; D001120:Arginine