title: Protein tyrosine phosphatase non-receptor type 22 modulates NOD2-induced cytokine release and autophagy.
abstract: BACKGROUND
  Variations within the gene locus encoding protein tyrosine phosphatase non-receptor type 22 (PTPN22) are associated with the risk to develop inflammatory bowel disease (IBD). PTPN22 is involved in the regulation of T- and B-cell receptor signaling, but although it is highly expressed in innate immune cells, its function in other signaling pathways is less clear. Here, we study whether loss of PTPN22 controls muramyl-dipeptide (MDP)-induced signaling and effects in immune cells.
  
  
  METHODS
  Stable knockdown of PTPN22 was induced in THP-1 cells by shRNA transduction prior to stimulation with the NOD2 ligand MDP. Cells were analyzed for signaling protein activation and mRNA expression by Western blot and quantitative PCR; cytokine secretion was assessed by ELISA, autophagosome induction by Western blot and immunofluorescence staining. Bone marrow derived dendritic cells (BMDC) were obtained from PTPN22 knockout mice or wild-type animals.
  
  
  RESULTS
  MDP-treatment induced PTPN22 expression and activity in human and mouse cells. Knockdown of PTPN22 enhanced MDP-induced activation of mitogen-activated protein kinase (MAPK)-isoforms p38 and c-Jun N-terminal kinase as well as canonical NF-κB signaling molecules in THP-1 cells and BMDC derived from PTPN22 knockout mice. Loss of PTPN22 enhanced mRNA levels and secretion of interleukin (IL)-6, IL-8 and TNF in THP-1 cells and PTPN22 knockout BMDC. Additionally, loss of PTPN22 resulted in increased, MDP-mediated autophagy in human and mouse cells.
  
  
  CONCLUSIONS
  Our data demonstrate that PTPN22 controls NOD2 signaling, and loss of PTPN22 renders monocytes more reactive towards bacterial products, what might explain the association of PTPN22 variants with IBD pathogenesis.
authors.affiliation: Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Marianne R
authors.initials: MR
authors.lastname: Spalinger
authors.forename: Silvia
authors.initials: S
authors.lastname: Lang
authors.forename: Stephan R
authors.initials: SR
authors.lastname: Vavricka
authors.forename: Michael
authors.initials: M
authors.lastname: Fried
authors.forename: Gerhard
authors.initials: G
authors.lastname: Rogler
authors.forename: Michael
authors.initials: M
authors.lastname: Scharl
mesh_terms: D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000494:pharmacology; D000818:Animals; D001343:Autophagy / Q000502:physiology*; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D055785:Gene Knockdown Techniques; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000235:genetics / Q000503:physiopathology; D051379:Mice; D018345:Mice, Knockout; D053473:Nod2 Signaling Adaptor Protein / Q000502:physiology*; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22 / Q000235:genetics / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D016207:Cytokines; C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein; C495945:Nod2 protein, mouse; D000119:Acetylmuramyl-Alanyl-Isoglutamine; C516765:PTPN22 protein, human; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22; C516766:Ptpn22 protein, mouse