title: Defective T-cell receptor gamma gene rearrangement in interleukin-7 receptor knockout mice.
abstract: T-cell receptor (TCR) genes need to be rearranged by a site specific-VDJ recombinase before they are expressed. This process, initiated in CD44+25+ thymocytes, takes place during the early stage of T-cell differentiation in the thymus. Interleukin-7 receptor alpha chain knockout (IL-7R-/-) mice are severely deficient in B-lymphocytes and alpha beta T-cells and completely lack the gamma delta T-cell lineage. Thymocyte development is arrested at a very early stage (DN CD44+CD25-). Because this arrest is earlier than in mice with a block in VDJ recombination, we examined the rearrangement status of TCR genes in thymocytes from IL-7R-/- mice. The TCR beta locus showed a nearly normal pattern of VDJ rearrangements, consistent with the presence of alpha beta T-cells in these mice. However, TCR gamma locus rearrangement was absent or severely reduced for all the V gamma genes analyzed (V gamma 3, V gamma 4, V gamma 1.1, V gamma 1.2 and V gamma 2). In contrast, the delta locus showed little reduction in rearrangement. The defect in gamma rearrangements in IL-7R-/- thymocytes is not simply due to an absence of mature gamma delta T-cells, since TCR delta-/- mice, which also have only alpha beta T-cells, had normal levels of gamma and delta rearrangements. These findings indicate that one or both of the two known ligands of IL-7R, IL-7 and thymic stromal lymphopoietin (TSLP) serves as an extrinsic signal to specifically rearrange the TCR gamma locus.
authors.affiliation: SAIC, NCI-FCRDC, Frederick, MD 21702-1201, USA. candeia@dsvgre.cea.fr
authors.forename: S
authors.initials: S
authors.lastname: Candéias
authors.forename: J J
authors.initials: JJ
authors.lastname: Peschon
authors.forename: K
authors.initials: K
authors.lastname: Muegge
authors.forename: S K
authors.initials: SK
authors.lastname: Durum
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics* / Q000502:physiology; D004254:DNA Nucleotidyltransferases / Q000378:metabolism; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor / Q000235:genetics; D015334:Gene Rearrangement, gamma-Chain T-Cell Antigen Receptor / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018123:Receptors, Interleukin / Q000235:genetics* / Q000502:physiology; D020395:Receptors, Interleukin-7; D045567:VDJ Recombinases
chemical_list: D015703:Antigens, CD; D018123:Receptors, Interleukin; D020395:Receptors, Interleukin-7; D004254:DNA Nucleotidyltransferases; D045567:VDJ Recombinases