title: Altered thymic positive selection and intracellular signals in Cbl-deficient mice.
abstract: Cbl is the product of the protooncogene c-cbl and is involved in T cell antigen receptor (TCR)-mediated signaling. To understand the role of Cbl for immune system development and function, we generated a Cbl-deficient mouse strain. In Cbl-deficient mice, positive selection of the thymocytes expressing major histocompatibility complex class II-restricted transgenic TCR was significantly enhanced. Two factors may have contributed to the altered thymic selection. First, Cbl deficiency markedly up-regulated the activity of ZAP-70 and mitogen-activated protein kinases. The mitogen-activated protein kinase pathway was shown previously to be involved in thymic positive selection. Second, Cbl-deficient thymocytes expressed CD3 and CD4 molecules at higher levels, which consequently may increase the avidity of TCR/major histocompatibility complex/coreceptor interaction. Thus, Cbl plays a novel role in modulating TCR-mediated multiple signaling pathways and fine-tunes the signaling threshold for thymic selection.
authors.affiliation: Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
authors.forename: M
authors.initials: M
authors.lastname: Naramura
authors.forename: H K
authors.initials: HK
authors.lastname: Kole
authors.forename: R J
authors.initials: RJ
authors.lastname: Hu
authors.forename: H
authors.initials: H
authors.lastname: Gu
mesh_terms: D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics; D005786:Gene Expression Regulation; D005802:Genes, MHC Class II; D008213:Lymphocyte Activation; D008285:Major Histocompatibility Complex; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D050721:Proto-Oncogene Proteins c-cbl; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000502:physiology*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics; D015183:Restriction Mapping; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*; D044767:Ubiquitin-Protein Ligases; D051746:ZAP-70 Protein-Tyrosine Kinase
chemical_list: D011518:Proto-Oncogene Proteins; D011948:Receptors, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D011505:Protein-Tyrosine Kinases; D051746:ZAP-70 Protein-Tyrosine Kinase; C497262:Zap70 protein, mouse; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C493849:Cbl protein, mouse