title: Role of SHP2 protein tyrosine phosphatase in SERT inhibition by enteropathogenicE. coli(EPEC).
abstract: EnteropathogenicEscherichia coli(EPEC), one of the diarrheagenicE. colipathotypes, is among the most important food-borne pathogens infecting children worldwide. Inhibition of serotonin transporter (SERT), which regulates extracellular availability of serotonin (5-HT), has been implicated previously in EPEC-associated diarrhea. EPEC was shown to inhibit SERT via activation of protein tyrosine phosphatase (PTPase), albeit the specific PTPase involved is not known. Current studies aimed to identify EPEC-activated PTPase and its role in SERT inhibition. Infection of Caco-2 monolayers with EPEC strain E2348/69 for 30 min increased the activity of Src-homology-2 domain containing PTPase (SHP2) but not SHP1 or PTPase 1B. Similarly, Western blot studies showed increased tyrosine phosphorylation of (p-tyrosine) SHP2, indicative of its activation. Concomitantly, EPEC infection decreased SERT p-tyrosine levels. This was associated with increased interaction of SHP2 with SERT, as evidenced by coimmunoprecipitation studies. To examine whether SHP2 directly influences SERT phosphorylation status or function, SHP2 cDNA plasmid constructs (wild type, constitutively active, or dominant negative) were overexpressed in Caco-2 cells by Amaxa electroporation. In the cells overexpressing constitutively active SHP2, SERT polypeptide showed complete loss of p-tyrosine. In addition, there was a decrease in SERT function, as measured by Na+Cl--sensitive [3H]5-HT uptake, and an increase in association of SERT with SHP2 in Caco-2 cells expressing constitutively active SHP2 compared with dominant-negative SHP2. Our data demonstrate that intestinal SERT is a target of SHP2 and reveal a novel mechanism by which a common food-borne pathogen uses cellular SHP2 to inhibit SERT.NEW & NOTEWORTHYThe data presented in the current study reveal that intestinal serotonin transporter (SERT) is a target of the tyrosine phosphatase SHP2 and show a novel mechanism by which a common diarrheagenic pathogen, EPEC, activates cellular SHP2 to inhibit SERT function. These studies highlight host-pathogen interactions, which may be of therapeutic relevance in the management of diarrhea associated with enteric infections.
authors.affiliation: Division of Gastroenterology and Hepatology, University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Megha
authors.initials: M
authors.lastname: Singhal
authors.affiliation: Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and.
authors.forename: Christopher
authors.initials: C
authors.lastname: Manzella
authors.affiliation: Division of Gastroenterology and Hepatology, University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Vinay
authors.initials: V
authors.lastname: Soni
authors.affiliation: Division of Gastroenterology and Hepatology, University of Illinois at Chicago, Chicago, Illinois.|Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois.
authors.forename: Waddah A
authors.initials: WA
authors.lastname: Alrefai
authors.affiliation: Division of Gastroenterology and Hepatology, University of Illinois at Chicago, Chicago, Illinois.|Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois.
authors.forename: Seema
authors.initials: S
authors.lastname: Saksena
authors.affiliation: Division of Gastroenterology and Nutrition, Departments of Medicine, Microbiology/Immunology, Loyola University Chicago, Chicago, Illinois.
authors.forename: Gail A
authors.initials: GA
authors.lastname: Hecht
authors.affiliation: Division of Gastroenterology and Hepatology, University of Illinois at Chicago, Chicago, Illinois.|Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois.
authors.forename: Pradeep K
authors.initials: PK
authors.lastname: Dudeja
authors.affiliation: Division of Gastroenterology and Hepatology, University of Illinois at Chicago, Chicago, Illinois; rgill@uic.edu.
authors.forename: Ravinder K
authors.initials: RK
authors.lastname: Gill
mesh_terms: D018938:Caco-2 Cells; D020895:Enterocytes / Q000378:metabolism* / Q000382:microbiology*; D054308:Enteropathogenic Escherichia coli / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D006801:Humans; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 / Q000378:metabolism*; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism*
chemical_list: D050486:Serotonin Plasma Membrane Transport Proteins; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11
keywords: 5-HT; Caco-2; SHP2; diarrhea; enteric infection