title: Fer and Fps/Fes participate in a Lyn-dependent pathway from FcepsilonRI to platelet-endothelial cell adhesion molecule 1 to limit mast cell activation.
abstract: Mast cells express the high affinity IgE receptor FcepsilonRI, which upon aggregation by multivalent antigens elicits signals that cause rapid changes within the mast cell and in the surrounding tissue. We previously showed that FcepsilonRI aggregation caused a rapid increase in phosphorylation of both Fer and Fps/Fes kinases in bone marrow-derived mast cells. In this study, we report that FcepsilonRI aggregation leads to increased Fer/Fps kinase activities and that Fer phosphorylation downstream of FcepsilonRI is independent of Syk, Fyn, and Gab2 but requires Lyn. Activated Fer/Fps readily phosphorylate the C terminus of platelet-endothelial cell adhesion molecule 1 (Pecam-1) on immunoreceptor tyrosine-based inhibitory motifs (ITIMs) and a non-ITIM residue (Tyr(700)) in vitro and in transfected cells. Mast cells devoid of Fer/Fps kinase activities display a reduction in FcepsilonRI aggregation-induced tyrosine phosphorylation of Pecam-1, with no defects in recruitment of Shp1/Shp2 phosphatases observed. Lyn-deficient mast cells display a dramatic reduction in Pecam-1 phosphorylation at Tyr(685) and a complete loss of Shp2 recruitment, suggesting a role as an initiator kinase for Pecam-1. Consistent with previous studies of Pecam-1-deficient mast cells, we observe an exaggerated degranulation response in mast cells lacking Fer/Fps kinases at low antigen dosages. Thus, Lyn and Fer/Fps kinases cooperate to phosphorylate Pecam-1 and activate Shp1/Shp2 phosphatases that function in part to limit mast cell activation.
authors.affiliation: Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Christian M
authors.initials: CM
authors.lastname: Udell
authors.affiliation: Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Lionel A
authors.initials: LA
authors.lastname: Samayawardhena
authors.affiliation: Division of Cell Biology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kawakami
authors.affiliation: Division of Cell Biology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kawakami
authors.affiliation: Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada. Electronic address: ac15@post.queensu.ca.
authors.forename: Andrew W B
authors.initials: AWB
authors.lastname: Craig
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000166:cytology; D002448:Cell Adhesion; D042783:Endothelial Cells / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry; D008407:Mast Cells / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000737:chemistry; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D051578:Proto-Oncogene Proteins c-fes / Q000502:physiology*; D017455:Receptors, IgE / Q000737:chemistry*; D019061:src-Family Kinases / Q000502:physiology*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D017455:Receptors, IgE; C052602:proto-oncogene protein c-fes-fps; D011505:Protein-Tyrosine Kinases; C496646:Fes protein, mouse; D051578:Proto-Oncogene Proteins c-fes; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse; C509248:Ptpn6 protein, mouse