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Garber JJ, Mallick EM, Scanlon KM, Turner JR, Donnenberg MS, Leong JM, Snapper SB. Attaching-and-Effacing Pathogens Exploit Junction Regulatory Activities of N-WASP and SNX9 to Disrupt the Intestinal Barrier. Cell Mol Gastroenterol Hepatol 2018; 5:273-88. [PMID: 29675452 DOI: 10.1016/j.jcmgh.2017.11.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
BACKGROUND & AIMS 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.
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Key Words
- ADF, actin depolymerization factor
- AE, attaching-and-effacing
- AJ, adherens junction
- AJC, apical junction complex
- Arp, actin-related protein
- CR, Citrobacter rodentium
- Crb, Crumbs
- Cytoskeleton
- DBS100, David B. Schauer 100
- EHEC, enterohemorrhagic Escherichia coli
- EM, electron microscopy
- EPEC, enteropathogenic Escherichia coli
- EcoRI, E. coli RY13 I
- EspF
- EspF, early secreted antigenic target-6 (ESX)-1 secretion-associated protein F
- FITC, fluorescein isothiocyanate
- Junction Regulation
- KO, knockout
- N-WASP
- N-WASP, Neural Wiskott-Aldrich Syndrome protein
- NWKD, Neural Wiskott-Aldrich Syndrome protein knockdown
- PBS, phosphate-buffered saline
- PCR, polymerase chain reaction
- SNX9, sorting nexin 9
- SNX9KD, sorting nexin 9 knockdown
- TER, transepithelial electrical resistance
- TJ, tight junction
- Tir, translocated intimin receptor
- ZO-1, zonula occludens-1
- iNWKO, intestine Neural Wiskott-Aldrich Syndrome protein knockout
- shRNA, short hairpin RNA
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Garber JJ, Mallick EM, Scanlon KM, Turner JR, Donnenberg MS, Leong JM, Snapper SB. Attaching-and-Effacing Pathogens Exploit Junction Regulatory Activities of N-WASP and SNX9 to Disrupt the Intestinal Barrier. Cell Mol Gastroenterol Hepatol 2017; 5:273-288. [PMID: 29675452 PMCID: PMC5904039 DOI: 10.1016/j.jcmgh.2017.11.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 11/28/2017] [Indexed: 02/05/2023]
Abstract
BACKGROUND & AIMS 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.
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Key Words
- ADF, actin depolymerization factor
- AE, attaching-and-effacing
- AJ, adherens junction
- AJC, apical junction complex
- Arp, actin-related protein
- CR, Citrobacter rodentium
- Crb, Crumbs
- Cytoskeleton
- DBS100, David B. Schauer 100
- EHEC, enterohemorrhagic Escherichia coli
- EM, electron microscopy
- EPEC, enteropathogenic Escherichia coli
- EcoRI, E. coli RY13 I
- EspF
- EspF, early secreted antigenic target-6 (ESX)-1 secretion-associated protein F
- FITC, fluorescein isothiocyanate
- Junction Regulation
- KO, knockout
- N-WASP
- N-WASP, Neural Wiskott-Aldrich Syndrome protein
- NWKD, Neural Wiskott-Aldrich Syndrome protein knockdown
- PBS, phosphate-buffered saline
- PCR, polymerase chain reaction
- SNX9, sorting nexin 9
- SNX9KD, sorting nexin 9 knockdown
- TER, transepithelial electrical resistance
- TJ, tight junction
- Tir, translocated intimin receptor
- ZO-1, zonula occludens-1
- iNWKO, intestine Neural Wiskott-Aldrich Syndrome protein knockout
- shRNA, short hairpin RNA
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Affiliation(s)
- John J. Garber
- Gastrointestinal Unit, Massachusetts General Hospital, Boston, Massachusetts,Division of Gastroenterology/Nutrition and Center for Inflammatory Bowel Disease Treatment and Research, Boston Children's Hospital, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Emily M. Mallick
- Department of Medicine Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Karen M. Scanlon
- Department of Medicine and Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland
| | - Jerrold R. Turner
- Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Michael S. Donnenberg
- Department of Medicine and Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland
| | - John M. Leong
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts
| | - Scott B. Snapper
- Division of Gastroenterology/Nutrition and Center for Inflammatory Bowel Disease Treatment and Research, Boston Children's Hospital, Boston, Massachusetts,Division of Gastroenterology and Hepatology, Brigham and Women's Hospital, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts,Correspondence Address correspondence to: Scott B. Snapper, MD, PhD, Division of Gastroenterology/Nutrition, Boston Children’s Hospital, Enders 676, 300 Longwood Avenue, Boston, Massachusetts 02115. fax: (617) 730-0498.
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