title: The microRNA biogenesis machinery modulates lineage commitment during αβ T cell development.
abstract: Differentiation of CD4(+) helper and CD8(+) cytotoxic αβ T cells from CD4(+)CD8(+) thymocytes involves upregulation of lineage-specifying transcription factors and transcriptional silencing of CD8 or CD4 coreceptors, respectively, in MHC class II or I (MHCII or I)-restricted thymocytes. In this study, we demonstrate that inactivation of the Dicer RNA endonuclease in murine thymocytes impairs initiation of Cd4 and Cd8 silencing, leading to development of positively selected MHCI- and MHCII-restricted mature CD4(+)CD8(+) thymocytes. Expression of the antiapoptotic BCL2 protein or inactivation of the p53 proapoptotic protein rescues these thymocytes from apoptosis, increasing their frequency and permitting accumulation of CD4(+)CD8(+) αβ T cells in the periphery. Dicer-deficient MHCI-restricted αβ T cells fail to normally silence Cd4 and display impaired induction of the CD8 lineage-specifying transcription factor Runx3, whereas Dicer-deficient MHCII-restricted αβ T cells show impaired Cd8 silencing and impaired induction of the CD4 lineage-specifying transcription factor Thpok. Finally, we show that the Drosha RNA endonuclease, which functions upstream of Dicer in microRNA biogenesis, also regulates Cd4 and Cd8 silencing. Our data demonstrate a previously dismissed function for the microRNA biogenesis machinery in regulating expression of lineage-specifying transcription factors and silencing of Cd4 and Cd8 during αβ T cell differentiation.
authors.affiliation: Division of Cancer Pathobiology, Department of Pathology and Laboratory Medicine, Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, PA 19104; Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Cell and Molecular Biology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104;
authors.forename: Levi J
authors.initials: LJ
authors.lastname: Rupp
authors.affiliation: Division of Cancer Pathobiology, Department of Pathology and Laboratory Medicine, Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, PA 19104; Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Integrative Immunobiology Unit, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892;
authors.forename: Brenna L
authors.initials: BL
authors.lastname: Brady
authors.affiliation: Laboratory of Immune Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892; and.
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Carpenter
authors.affiliation: Immunology Graduate Group, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104.
authors.forename: Maria Elena
authors.initials: ME
authors.lastname: De Obaldia
authors.affiliation: Immunology Graduate Group, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104.
authors.forename: Avinash
authors.initials: A
authors.lastname: Bhandoola
authors.affiliation: Laboratory of Immune Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892; and.
authors.forename: Remy
authors.initials: R
authors.lastname: Bosselut
authors.affiliation: Integrative Immunobiology Unit, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892;
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Muljo
authors.affiliation: Division of Cancer Pathobiology, Department of Pathology and Laboratory Medicine, Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, PA 19104; Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Cell and Molecular Biology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Immunology Graduate Group, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 bassing@email.chop.edu.
authors.forename: Craig H
authors.initials: CH
authors.lastname: Bassing
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology; D015704:CD4 Antigens / Q000235:genetics / Q000276:immunology; D016827:CD8 Antigens / Q000235:genetics / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology; D019070:Cell Lineage / Q000276:immunology; D050677:Core Binding Factor Alpha 3 Subunit / Q000276:immunology; D053487:DEAD-box RNA Helicases / Q000235:genetics*; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000096:biosynthesis / Q000235:genetics*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics*; D043244:Ribonuclease III / Q000235:genetics*; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology* / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000166:cytology* / Q000276:immunology; D014157:Transcription Factors / Q000276:immunology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D050677:Core Binding Factor Alpha 3 Subunit; D053487:DEAD-box RNA Helicases; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D035683:MicroRNAs; D019253:Proto-Oncogene Proteins c-bcl-2; D016693:Receptors, Antigen, T-Cell, alpha-beta; D043244:Ribonuclease III; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; C493730:Runx3 protein, mouse; C497211:Zbtb7b protein, mouse; C509781:Dicer1 protein, mouse; C513400:Drosha protein, mouse