title: Allelic exclusion and differentiation by protein kinase C-mediated signals in immature thymocytes.
abstract: Pre-T cell receptor (preTCR)-derived signals mediate the transition of thymocytes from the CD4(-) CD8(-) double-negative (DN) to CD4(+) CD8(+) double-positive stage of T lymphocyte development. This progression, termed beta-selection, is limited to thymocytes that have generated a functional TCR-beta chain able to associate with pTalpha to form the preTCR complex. Formation of the preTCR complex not only induces differentiation, survival, and proliferation of DN thymocytes; it also inhibits further TCR-beta gene rearrangement through an ill-defined process known as allelic exclusion. The signaling pathways controlling this critical developmental checkpoint have not been characterized. Here we demonstrate that formation of the preTCR complex leads to the activation of protein kinase C (PKC), and that activation of PKC is necessary for the differentiation and expansion of DN thymocytes. Importantly, we also show that allelic exclusion at the TCR-beta gene loci is enforced by PKC-mediated signals. These results define PKC as a central mediator of both differentiation and allelic exclusion during thymocyte development.
authors.affiliation: Department of Immunology, University of Toronto, Toronto, ON, Canada M5S 1A8.
authors.forename: A M
authors.initials: AM
authors.lastname: Michie
authors.forename: J W
authors.initials: JW
authors.lastname: Soh
authors.forename: R G
authors.initials: RG
authors.lastname: Hawley
authors.forename: I B
authors.initials: IB
authors.lastname: Weinstein
authors.forename: J C
authors.initials: JC
authors.lastname: Zuniga-Pflucker
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000483:Alleles; D000818:Animals; D019470:Biolistics; D002454:Cell Differentiation; D017637:Clonal Deletion / Q000502:physiology*; D004268:DNA-Binding Proteins; D004789:Enzyme Activation; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor; D005799:Genes, Dominant; D017930:Genes, Reporter; D006410:Hematopoiesis / Q000502:physiology*; D007527:Isoenzymes / Q000235:genetics / Q000502:physiology*; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D009924:Organ Culture Techniques; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010750:Phosphoproteins / Q000502:physiology; D011493:Protein Kinase C / Q000235:genetics / Q000502:physiology*; D051571:Protein Kinase C-alpha; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D019908:Proto-Oncogene Proteins c-raf / Q000502:physiology; D016283:Proto-Oncogene Proteins p21(ras) / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000502:physiology; D015398:Signal Transduction; D016176:T-Lymphocyte Subsets / Q000166:cytology*; D013950:Thymus Gland / Q000166:cytology*; D014162:Transfection; D010738:Type C Phospholipases / Q000502:physiology; D051746:ZAP-70 Protein-Tyrosine Kinase
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; D007527:Isoenzymes; D010750:Phosphoproteins; C499308:Rag2 protein, mouse; D011993:Recombinant Fusion Proteins; C092947:SLP-76 signal Transducing adaptor proteins; C064655:V(D)J recombination activating protein 2; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051746:ZAP-70 Protein-Tyrosine Kinase; C497262:Zap70 protein, mouse; D019908:Proto-Oncogene Proteins c-raf; C496630:Prkca protein, mouse; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D010738:Type C Phospholipases; D016283:Proto-Oncogene Proteins p21(ras); D043265:Phosphatidylinositol Diacylglycerol-Lyase