A new role for reticulon-4B/NOGO-B in the intestinal epithelial barrier function and inflammatory bowel disease

作者：Rodriguez Feo Juan Antonio; Puerto Marta; Fernandez Mena Carolina; Verdejo Cristina; Lara Jose Manuel; Diaz Sanchez Maria; Alvarez Emilio; Vaquero Javier; Marin Jimenez Ignacio; Banares Rafael; Menchen Luis^*

来源：American Journal of Physiology - Gastrointestinal and Liver Physiology, 2015, 308(12): G981-G993.

DOI：10.1152/ajpgi.00309.2014

• reticulon-4B/NOGO-B
• intestinal epithelial cells
• intestinal barrier
• inflammatory bowel disease
• Crohn's disease
• E-cadherin

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 alpha-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, alpha-catenin expression, and actin cytoskeleton organization at sites of cell-to-cell contacts.

• 出版日期2015-6-15