title: RelB reduces thymocyte apoptosis and regulates terminal thymocyte maturation.
abstract: Thymocyte maturation is controlled by successive developmental checkpoints connected to the acquisition of a functional T cell receptor (TCR). During thymocyte selection, engagement of the TCR regulates the fine balance between death and survival signals. At the final stages of single-positive (SP) thymocyte maturation, the coupling of the TCR changes from death- to proliferation-inducing signals, a competence required for optimal effector functions in the periphery. We show here that in RelB mutant thymuses, thymocyte differentiation of CD24(-) SP cells is partially impaired. Competitive bone marrow reconstitution experiments show that this defect is constitutive to the lymphoid compartment. This is accompanied by an increased proportion of apoptotic thymocytes and a drastically reduced proliferation upon activation with anti-CD3 antibody/PMA stimulation. Thus, the RelB protein contributes to the quality of cell signaling in thymocytes by providing anti-apoptotic signals. These results suggest that in addition to its major role on the activation of antigen-presenting cell function, the RelB protein is intrinsically required for terminal thymocyte differentiation and activation.
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, CNRS-INSERM-Université de la Méditerranée, Marseille, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Guerin
authors.forename: Marie-Laurence
authors.initials: ML
authors.lastname: Baron
authors.forename: René
authors.initials: R
authors.lastname: Valero
authors.forename: Magali
authors.initials: M
authors.lastname: Herrant
authors.forename: Patrick
authors.initials: P
authors.lastname: Auberger
authors.forename: Philippe
authors.initials: P
authors.lastname: Naquet
mesh_terms: D000818:Animals; D017209:Apoptosis; D002454:Cell Differentiation; D002455:Cell Division; D015870:Gene Expression; D020935:MAP Kinase Signaling System; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D010641:Phenotype; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology*; D051841:Transcription Factor RelB; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D016328:NF-kappa B; D011518:Proto-Oncogene Proteins; D011948:Receptors, Antigen, T-Cell; C497594:Relb protein, mouse; D014157:Transcription Factors; D051841:Transcription Factor RelB