title: Pre-TCR ligand binding impacts thymocyte development before αβTCR expression.
abstract: Adaptive cellular immunity requires accurate self- vs. nonself-discrimination to protect against infections and tumorous transformations while at the same time excluding autoimmunity. This vital capability is programmed in the thymus through selection of αβT-cell receptors (αβTCRs) recognizing peptides bound to MHC molecules (pMHC). Here, we show that the pre-TCR (preTCR), a pTα-β heterodimer appearing before αβTCR expression, directs a previously unappreciated initial phase of repertoire selection. Contrasting with the ligand-independent model of preTCR function, we reveal through NMR and bioforce-probe analyses that the β-subunit binds pMHC using Vβ complementarity-determining regions as well as an exposed hydrophobic Vβ patch characteristic of the preTCR. Force-regulated single bonds akin to those of αβTCRs but with more promiscuous ligand specificity trigger calcium flux. Thus, thymic development involves sequential β- and then, αβ-repertoire tuning, whereby preTCR interactions with self pMHC modulate early thymocyte expansion, with implications for β-selection, immunodominant peptide recognition, and germ line-encoded MHC interaction.
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115;
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Mallis
authors.affiliation: Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332;
authors.forename: Ke
authors.initials: K
authors.lastname: Bai
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115;
authors.forename: Haribabu
authors.initials: H
authors.lastname: Arthanari
authors.affiliation: Department of Medical Oncology, Laboratory of Immunobiology, Dana-Farber Cancer Institute, Boston, MA 02115;
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Hussey
authors.affiliation: Department of Medical Oncology, Laboratory of Immunobiology, Dana-Farber Cancer Institute, Boston, MA 02115;
authors.forename: Maris
authors.initials: M
authors.lastname: Handley
authors.affiliation: Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332;
authors.forename: Zhenhai
authors.initials: Z
authors.lastname: Li
authors.affiliation: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332;
authors.forename: Loice
authors.initials: L
authors.lastname: Chingozha
authors.affiliation: Department of Medical Oncology, Laboratory of Immunobiology, Dana-Farber Cancer Institute, Boston, MA 02115; Department of Medicine, Harvard Medical School, Boston, MA 02115;
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Duke-Cohan
authors.affiliation: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332;
authors.forename: Hang
authors.identifier: http://orcid.org/0000-0002-6881-660X
authors.initials: H
authors.lastname: Lu
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115; Department of Medical Oncology, Laboratory of Immunobiology, Dana-Farber Cancer Institute, Boston, MA 02115; Department of Pediatrics, Harvard Medical School, Boston, MA 02115.
authors.forename: Jia-Huai
authors.initials: JH
authors.lastname: Wang
authors.affiliation: Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332;
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhu
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115;
authors.forename: Gerhard
authors.initials: G
authors.lastname: Wagner
authors.affiliation: Department of Medical Oncology, Laboratory of Immunobiology, Dana-Farber Cancer Institute, Boston, MA 02115; Department of Medicine, Harvard Medical School, Boston, MA 02115; ellis_reinherz@dfci.harvard.edu.
authors.forename: Ellis L
authors.initials: EL
authors.lastname: Reinherz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000276:immunology / Q000378:metabolism; D002454:Cell Differentiation / Q000276:immunology*; D002478:Cells, Cultured; D022801:Complementarity Determining Regions / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D005434:Flow Cytometry; D006649:Histocompatibility Antigens / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D008024:Ligands; D008213:Lymphocyte Activation / Q000276:immunology; D009682:Magnetic Resonance Spectroscopy; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018448:Models, Immunological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding / Q000276:immunology; D055503:Protein Multimerization / Q000276:immunology; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D060168:Thymocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D013950:Thymus Gland / Q000196:embryology / Q000276:immunology / Q000378:metabolism
chemical_list: D022801:Complementarity Determining Regions; D006649:Histocompatibility Antigens; D008024:Ligands; D010455:Peptides; D016693:Receptors, Antigen, T-Cell, alpha-beta; D002118:Calcium
keywords: NMR spectroscopy; biomembrane force probe; pre–T-cell receptor; repertoire selection; thymic development