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Attaching-and-Effacing Pathogens Exploit Junction Regulatory Activities of N-WASP and SNX9 to Disrupt the Intestinal Barrier

Authors :
John J. Garber
Emily M. Mallick
Karen M. Scanlon
Jerrold R. Turner
Michael S. Donnenberg
John M. Leong
Scott B. Snapper
Source :
Cellular and Molecular Gastroenterology and Hepatology, Vol 5, Iss 3, Pp 273-288 (2018)
Publication Year :
2018
Publisher :
Elsevier, 2018.

Abstract

Neural Wiskott-Aldrich Syndrome protein (N-WASP) is a key regulator of the actin cytoskeleton in epithelial tissues and is poised to mediate cytoskeletal-dependent aspects of apical junction complex (AJC) homeostasis. Attaching-and-effacing (AE) pathogens disrupt this homeostasis through translocation of the effector molecule early secreted antigenic target-6 (ESX)-1 secretion-associated protein F (EspF). Although the mechanisms underlying AJC disruption by EspF are unknown, EspF contains putative binding sites for N-WASP and the endocytic regulator sorting nexin 9 (SNX9). We hypothesized that N-WASP regulates AJC integrity and AE pathogens use EspF to induce junction disassembly through an N-WASP– and SNX9-dependent pathway. Methods: We analyzed mice with intestine-specific N-WASP deletion and generated cell lines with N-WASP and SNX9 depletion for dynamic functional assays. We generated EPEC and Citrobacter rodentium strains complemented with EspF bearing point mutations abolishing N-WASP and SNX9 binding to investigate the requirement for these interactions. Results: Mice lacking N-WASP in the intestinal epithelium showed spontaneously increased permeability, abnormal AJC morphology, and mislocalization of occludin. N-WASP depletion in epithelial cell lines led to impaired assembly and disassembly of tight junctions in response to changes in extracellular calcium. Cells lacking N-WASP or SNX9 supported actin pedestals and type III secretion, but were resistant to EPEC-induced AJC disassembly and loss of transepithelial resistance. We found that during in vivo infection with AE pathogens, EspF must bind both N-WASP and SNX9 to disrupt AJCs and induce intestinal barrier dysfunction. Conclusions: Overall, these studies show that N-WASP critically regulates AJC homeostasis, and the AE pathogen effector EspF specifically exploits both N-WASP and SNX9 to disrupt intestinal barrier integrity during infection.

Details

Language :
English
ISSN :
2352345X
Volume :
5
Issue :
3
Database :
Directory of Open Access Journals
Journal :
Cellular and Molecular Gastroenterology and Hepatology
Publication Type :
Academic Journal
Accession number :
edsdoj.26c868dc14c44258353e4ebc05e513c
Document Type :
article
Full Text :
https://doi.org/10.1016/j.jcmgh.2017.11.015