title: Human intestinal MUC17 mucin augments intestinal cell restitution and enhances healing of experimental colitis.
abstract: The membrane-bound mucins, MUC17 (human) and Muc3 (mouse), are highly expressed on the apical surface of intestinal epithelia and are thought to be cytoprotective. The extracellular regions of these mucins contain EGF-like Cys-rich segments (CRD1 and CRD2) connected by an intervening linker domain (L). The purpose of this study was to determine the functional activity of human MUC17 membrane-bound mucin.
  
  
  METHODS
  Endogenous MUC17 was inhibited in LS174T colon cells by stable transfection of a small hairpin RNA targeting MUC17 (LSsi cells). The effect of recombinant MUC17-CRD1-L-CRD2 protein on migration, apoptosis, and experimental colitis was determined.
  
  
  RESULTS
  Reduced MUC17 expression in LSsi cells was associated with visibly reduced cell aggregation, reduced cell-cell adherence, and reduced cell migration, but no change in tumorigenicity. LSsi cells also demonstrated a 3.7-fold increase in apoptosis rates compared with control cells following treatment with etoposide. Exposure of colonic cell lines to exogenous recombinant MUC17-CRD1-L-CRD2 protein significantly increased cell migration and inhibited apoptosis. As a marker of biologic activity, MUC17-CRD1-L-CRD2 proteins stimulate ERK phosphorylation in colonic cell lines; and inhibition of ERK phosphorylation reduced the anti-apoptosis and migratory effect of MUC17-CRD1-L-CRD2. Finally, mice treated with MUC17-CRD1-L-CRD2 protein given per rectum demonstrated accelerated healing in acetic acid and dextran sodium sulfate induced colitis in vivo. These data indicate that both native MUC17 and the exogenous recombinant cysteine-rich domain of MUC17 play a role in diverse cellular mechanisms related to cell restitution, and suggest a potential role for MUC17-CRD1-L-CRD2 recombinant protein in the treatment of mucosal inflammatory diseases.
authors.affiliation: Department of Medicine, VA San Diego Healthcare System and University of California San Diego, 3350 La Jolla Village Drive, San Diego, CA 92161, United States.
authors.forename: Ying
authors.initials: Y
authors.lastname: Luu
authors.forename: Wade
authors.initials: W
authors.lastname: Junker
authors.forename: Satyanarayana
authors.initials: S
authors.lastname: Rachagani
authors.forename: Srustidhar
authors.initials: S
authors.lastname: Das
authors.forename: Surinder K
authors.initials: SK
authors.lastname: Batra
authors.forename: Robert L
authors.initials: RL
authors.lastname: Heinrikson
authors.forename: Laurie L
authors.initials: LL
authors.lastname: Shekels
authors.forename: Samuel B
authors.initials: SB
authors.lastname: Ho
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D002448:Cell Adhesion / Q000187:drug effects / Q000235:genetics; D002449:Cell Aggregation / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003092:Colitis / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D023421:Models, Animal; D009077:Mucins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D009368:Neoplasm Transplantation; D015202:Protein Engineering; D034741:RNA, Small Interfering / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D014945:Wound Healing / Q000187:drug effects
chemical_list: C450720:MUC17 protein, human; D009077:Mucins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins