title: Protein kinase C-theta is required for efficient positive selection.
abstract: Protein kinase C-theta (PKCtheta) is critical for TCR-initiated signaling in mature T cells, but initial reports found no requirement for PKCtheta in thymocyte development. Thymocytes and peripheral T cells utilize many of the same signaling components and, given the significant role of PKCtheta in peripheral T cells, it was surprising that it was not involved at all in TCR signaling in thymocytes. We decided to re-evaluate the role of PKCtheta in thymocyte development using the well-characterized class II-restricted n3.L2 TCR-transgenic TCR model. Analysis of n3.L2 PKCtheta(-/-) mice revealed a defect in thymocyte-positive selection, resulting in a 50% reduction in the generation of n3.L2 CD4 single-positive thymocytes and n3.L2 CD4 mature T cells. Competition between n3.L2 WT and n3.L2 PKCtheta(-/-) thymocytes in bone marrow chimeras revealed a more dramatic defect, with a >80% reduction in generation of n3.L2 CD4 single-positive thymocytes derived from PKCtheta(-/-) mice. Inefficient positive selection of n3.L2 PKCtheta(-/-) CD4 single-positive cells resulted from "weaker" signaling through the TCR and correlated with diminished ERK activation. The defect in positive selection was not complete in the PKCtheta(-/-) mice, most likely accounted for by compensation by other PKC isoforms not evident in peripheral cells. Similar decreased positive selection of both CD4 and CD8 single-positive thymocytes was also seen in nontransgenic PKCtheta(-/-) mice. These findings now place PKCtheta as a key signaling molecule in the positive selection of thymocytes as well as in the activation of mature T cells.
authors.affiliation: Department of Pediatrics, Division of Pediatric Infectious Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Sharon Celeste
authors.initials: SC
authors.lastname: Morley
authors.forename: K Scott
authors.initials: KS
authors.lastname: Weber
authors.forename: Henry
authors.initials: H
authors.lastname: Kao
authors.forename: Paul M
authors.initials: PM
authors.lastname: Allen
mesh_terms: D000818:Animals; D015704:CD4 Antigens / Q000096:biosynthesis; D016827:CD8 Antigens / Q000096:biosynthesis; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology*; D002460:Cell Line; D002470:Cell Survival / Q000235:genetics / Q000276:immunology; D007527:Isoenzymes / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology; D018655:Lymphocyte Count; D051379:Mice; D008806:Mice, Inbred AKR; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011493:Protein Kinase C / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D000074121:Protein Kinase C-theta; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000166:cytology* / Q000201:enzymology* / Q000276:immunology
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D007527:Isoenzymes; C489593:Prkcq protein, mouse; D011493:Protein Kinase C; D000074121:Protein Kinase C-theta
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