title: Phosphatidylinositol 3-kinase improves the efficiency of positive selection.
abstract: We have generated transgenic mice expressing the amino-terminal fragment of the phosphatidylinositol 3-kinase (PI3K) catalytic subunit (p110ABD) in thymocytes. Expression of p110ABD results in constitutive activation of PI3K and in significant increases in the numbers of mature, single-positive thymocytes. We previously reported that the increase in mature cells was in part due to a defect in thymic emigration. In this study we identify another component to this phenotype. Expression of p110ABD results in an enhancement of positive selection, without alterations in thymocyte lifespan or negative selection. Since PI3K can affect activation of Btk, which in turn potentiates calcium fluxes, during B cell development, our results suggest that PI3K could play a role in the regulation of Itk kinases in T cells, and that both cell types share a common signaling network to modulate calcium responses downstream of their antigen receptor.
authors.affiliation: Division of Biology, California Institute of Technology, 1200 E. California Boulevard, Mail code 147-75, Pasadena, CA 91125, USA.
authors.forename: Susannah D
authors.initials: SD
authors.lastname: Barbee
authors.forename: José
authors.initials: J
authors.lastname: Alberola-Ila
mesh_terms: D000077329:Agammaglobulinaemia Tyrosine Kinase; D000818:Animals; D001402:B-Lymphocytes / Q000201:enzymology / Q000276:immunology*; D020013:Calcium Signaling / Q000235:genetics / Q000276:immunology*; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology*; D002465:Cell Movement / Q000235:genetics / Q000276:immunology; D058534:Class I Phosphatidylinositol 3-Kinases; D004789:Enzyme Activation / Q000235:genetics / Q000276:immunology; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000276:immunology*; D017434:Protein Structure, Tertiary / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000276:immunology; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology / Q000201:enzymology / Q000276:immunology*
chemical_list: D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C497132:PIK3CB protein, human; D011505:Protein-Tyrosine Kinases; D000077329:Agammaglobulinaemia Tyrosine Kinase; C000625949:BTK protein, human; C080813:emt protein-tyrosine kinase