title: A spontaneous mutation of the rat Themis gene leads to impaired function of regulatory T cells linked to inflammatory bowel disease.
abstract: Spontaneous or chemically induced germline mutations, which lead to Mendelian phenotypes, are powerful tools to discover new genes and their functions. Here, we report an autosomal recessive mutation that occurred spontaneously in a Brown-Norway (BN) rat colony and was identified as causing marked T cell lymphopenia. This mutation was stabilized in a new rat strain, named BN(m) for "BN mutated." In BN(m) rats, we found that the T cell lymphopenia originated in the thymus, was intrinsic to CD4 T lymphocytes, and was associated with the development of an inflammatory bowel disease. Furthermore, we demonstrate that the suppressive activity of both peripheral and thymic CD4(+) CD25(bright) regulatory T cells (Treg) is defective in BN(m) rats. Complementation of mutant animals with BN Treg decreases disease incidence and severity, thus suggesting that the impaired Treg function is involved in the development of inflammatory bowel disease in BN(m) rats. Moreover, the cytokine profile of effector CD4 T cells is skewed toward Th2 and Th17 phenotypes in BN(m) rats. Linkage analysis and genetic dissection of the CD4 T cell lymphopenia in rats issued from BN(m)×DA crosses allowed the localization of the mutation on chromosome 1, within a 1.5 megabase interval. Gene expression and sequencing studies identified a frameshift mutation caused by a four-nucleotide insertion in the Themis gene, leading to its disruption. This result is the first to link Themis to the suppressive function of Treg and to suggest that, in Themis-deficient animals, defect of this function is involved in intestinal inflammation. Thus, this study highlights the importance of Themis as a new target gene that could participate in the pathogenesis of immune diseases characterized by chronic inflammation resulting from a defect in the Treg compartment.
authors.forename: Marianne
authors.initials: M
authors.lastname: Chabod
authors.forename: Christophe
authors.initials: C
authors.lastname: Pedros
authors.forename: Lucille
authors.initials: L
authors.lastname: Lamouroux
authors.forename: Céline
authors.initials: C
authors.lastname: Colacios
authors.forename: Isabelle
authors.initials: I
authors.lastname: Bernard
authors.forename: Dominique
authors.initials: D
authors.lastname: Lagrange
authors.forename: Daniela
authors.initials: D
authors.lastname: Balz-Hara
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Mosnier
authors.forename: Christian
authors.initials: C
authors.lastname: Laboisse
authors.forename: Nathalie
authors.initials: N
authors.lastname: Vergnolle
authors.forename: Olivier
authors.initials: O
authors.lastname: Andreoletti
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Roth
authors.forename: Roland
authors.initials: R
authors.lastname: Liblau
authors.forename: Gilbert J
authors.initials: GJ
authors.lastname: Fournié
authors.forename: Abdelhadi
authors.initials: A
authors.lastname: Saoudi
authors.forename: Anne S
authors.initials: AS
authors.lastname: Dejean
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D002874:Chromosome Mapping; D016368:Frameshift Mutation; D008040:Genetic Linkage; D015212:Inflammatory Bowel Diseases / Q000235:genetics* / Q000378:metabolism; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism; D008231:Lymphopenia / Q000235:genetics*; D051381:Rats; D050378:T-Lymphocytes, Regulatory / Q000378:metabolism*; D058504:Th17 Cells / Q000378:metabolism; D018418:Th2 Cells / Q000378:metabolism; D013950:Thymus Gland / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D053645:Interleukin-2 Receptor alpha Subunit