title: A new role for reticulon-4B/NOGO-B in the intestinal epithelial barrier function and inflammatory bowel disease.
abstract: Inflammatory bowel disease (IBD) is characterized by an impaired intestinal barrier function. We aimed to investigate the role of reticulon-4B (RTN-4B/NOGO-B), a structural protein of the endoplasmic reticulum, in intestinal barrier function and IBD. We used immunohistochemistry, confocal microscopy, real-time PCR, and Western blotting to study tissue distribution and expression levels of RTN-4B/NOGO-B in control and IBD samples from mouse and humans. We also targeted RTN-4B/NOGO-B using siRNAs in cultured human intestinal epithelial cell (IECs). Epithelial barrier permeability was assessed by transepithelial electrical resistance (TEER) measurement. RTN-4B/NOGO-B is expressed in the intestine mainly by IECs. Confocal microscopy revealed a colocalization of RTN-4B, E-cadherin, and polymerized actin fibers in tissue and cultured IECs. RTN-4B mRNA and protein expression were lower in the colon of IL-10(-/-) compared with wild-type mice. Colocalization of RTN-4B/E-cadherin/actin was reduced in the colon of IL-10(-/-) mice. Analysis of endoscopic biopsies from IBD patients showed a significant reduction of RTN-4B/NOGO-B expression in inflamed mucosa compared with control. Treatment of IECs with H2O2 reduced TEER values and triggered phosphorylation of RTN-4B in serine 107 residues as well as downregulation of RTN-4B expression. Acute RTN-4B/NOGO-B knockdown by siRNAs resulted in a decreased TEER values and reduction of E-cadherin and α-catenin expression and in the amount of F-actin-rich filaments in IECs. Epithelial RTN-4B/NOGO-B was downregulated in human and experimental IBD. RTN-4B participates in the intestinal epithelial barrier function, most likely via its involvement in E-cadherin, α-catenin expression, and actin cytoskeleton organization at sites of cell-to-cell contacts.
authors.affiliation: Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón: Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Barcelona, Spain;
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Rodríguez-Feo
authors.affiliation: Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón: Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Barcelona, Spain;
authors.forename: Marta
authors.initials: M
authors.lastname: Puerto
authors.affiliation: Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón: Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Barcelona, Spain;
authors.forename: Carolina
authors.initials: C
authors.lastname: Fernández-Mena
authors.affiliation: Servicio de Aparato Digestivo, Hospital General de Ciudad Real, Ciudad Real, Spain;
authors.forename: Cristina
authors.initials: C
authors.lastname: Verdejo
authors.affiliation: Servicio de Anatomía Patológica, Hospital General Universitario Gregorio Marañón, Madrid, Spain; and.
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Lara
authors.affiliation: Servicio de Anatomía Patológica, Hospital General Universitario Gregorio Marañón, Madrid, Spain; and.
authors.forename: María
authors.initials: M
authors.lastname: Díaz-Sánchez
authors.affiliation: Servicio de Anatomía Patológica, Hospital General Universitario Gregorio Marañón, Madrid, Spain; and.
authors.forename: Emilio
authors.initials: E
authors.lastname: Álvarez
authors.affiliation: Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón: Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Barcelona, Spain;
authors.forename: Javier
authors.initials: J
authors.lastname: Vaquero
authors.affiliation: Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón: Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain;
authors.forename: Ignacio
authors.initials: I
authors.lastname: Marín-Jiménez
authors.affiliation: Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón: Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Barcelona, Spain; Departamento de Medicina, Facultad de Medicina, Universidad Complutense, Madrid, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Bañares
authors.affiliation: Servicio de Aparato Digestivo, Hospital General Universitario Gregorio Marañón: Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Barcelona, Spain; Departamento de Medicina, Facultad de Medicina, Universidad Complutense, Madrid, Spain lamenchen.hgugm@salud.madrid.org.
authors.forename: Luis
authors.initials: L
authors.lastname: Menchén
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D015820:Cadherins / Q000378:metabolism; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015212:Inflammatory Bowel Diseases / Q000378:metabolism* / Q000473:pathology; D016753:Interleukin-10 / Q000172:deficiency / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009185:Myelin Proteins / Q000235:genetics / Q000378:metabolism*; D000070798:Nogo Proteins; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D019108:Tight Junctions / Q000378:metabolism*
chemical_list: D000199:Actins; D015820:Cadherins; C556062:IL10 protein, mouse; D009185:Myelin Proteins; D000070798:Nogo Proteins; C000603199:RTN4 protein, human; C000603201:Rtn4 protein, mouse; D016753:Interleukin-10; D006861:Hydrogen Peroxide
keywords: Crohn's disease; E-cadherin; inflammatory bowel disease; intestinal barrier; intestinal epithelial cells; reticulon-4B/NOGO-B