Interactions between Idd5.1/Ctla4 and Other Type 1 Diabetes Genes Kara Hunter, Dan Rainbow, Vincent Plagnol, John A. Todd, Laurence B. Peterson and Linda S. Wicker This information is current as of September 23, 2021. J Immunol 2007; 179:8341-8349; ; doi: 10.4049/jimmunol.179.12.8341 http://www.jimmunol.org/content/179/12/8341 Downloaded from References This article cites 32 articles, 15 of which you can access for free at: http://www.jimmunol.org/content/179/12/8341.full#ref-list-1 Why The JI? Submit online. http://www.jimmunol.org/ • Rapid Reviews! 30 days* from submission to initial decision • No Triage! Every submission reviewed by practicing scientists • Fast Publication! 4 weeks from acceptance to publication *average by guest on September 23, 2021 Subscription Information about subscribing to The Journal of Immunology is online at: http://jimmunol.org/subscription Permissions Submit copyright permission requests at: http://www.aai.org/About/Publications/JI/copyright.html Email Alerts Receive free email-alerts when new articles cite this article. Sign up at: http://jimmunol.org/alerts The Journal of Immunology is published twice each month by The American Association of Immunologists, Inc., 1451 Rockville Pike, Suite 650, Rockville, MD 20852 Copyright © 2007 by The American Association of Immunologists All rights reserved. Print ISSN: 0022-1767 Online ISSN: 1550-6606. The Journal of Immunology Interactions between Idd5.1/Ctla4 and Other Type 1 Diabetes Genes1 Kara Hunter,* Dan Rainbow,* Vincent Plagnol,* John A. Todd,* Laurence B. Peterson,† and Linda S. Wicker2* Two loci, Idd5.1 and Idd5.2, that determine susceptibility to type 1 diabetes (T1D) in the NOD mouse are on chromosome 1. Idd5.1 is likely accounted for by a synonymous single nucleotide polymorphism in exon 2 of Ctla4: the B10-derived T1D-resistant allele increases the expression of the ligand-independent isoform of CTLA-4 (liCTLA-4), a molecule that mediates negative signaling in T cells. Idd5.2 is probably Nramp1 (Slc11a1), which encodes a phagosomal membrane protein that is a metal efflux pump and is important for host defense and Ag presentation. In this study, two additional loci, Idd5.3 and Idd5.4, have been defined to 3.553 and 78 Mb regions, respectively, on linked regions of chromosome 1. The most striking findings, however, concern the evidence we have obtained for strong interactions between these four disease loci that help explain the association of human CTLA4 with Downloaded from T1D. In the presence of a susceptibility allele at Idd5.4, the CTLA-4 resistance allele causes an 80% reduction in T1D, whereas in the presence of a protective allele at Idd5.4, the effects of the resistance allele at Ctla4 are modest or, as in the case in which resistance alleles at Idd5.2 and Idd5.3 are present, completely masked. This masking of CTLA-4 alleles by different genetic backgrounds provides an explanation for our observation that the human CTLA-4 gene is only associated with T1D in the subgroup of human T1D patients with anti-thyroid autoimmunity. The Journal of Immunology, 2007, 179: 8341–8349. http://www.jimmunol.org/ enes termed insulin-dependent diabetes (Idd)3 control the de- (liCTLA-4) than does the NOD allele (6). The molecular basis for the velopment of type 1 diabetes (T1D) in NOD mice. The Idd5 splicing difference has been mapped to a single nucleotide polymorphism G region from diabetes-resistant C57BL/10 (B10) or C57BL/6 (SNP) in Ctla4 exon 2 that alters splicing in a similar manner to that (B6) mice provides protection from T1D when introgressed onto the mediated by a SNP in the human CD45 gene (7–9). The liCTLA-4 mol- NOD background (1–2). Idd5 is located on mouse chromosome 1 and ecule mediates negative signaling in T cells thereby predicting that its has been shown by congenic strain analysis to consist of at least two loci, higher expression in mice with the diabetes-protective B10 allele leads to Idd5.1 and Idd5.2, positioned at the proximal and distal ends, respec- reduced T cell activation and/or expansion (10). The Idd5.2 region was tively, of an ϳ15 Mb interval (3). Idd5.1 was defined as a 2.0 Mb B10- localized to a 1.5 Mb interval (3) in which Nramp1 is the most compel- by guest on September 23, 2021 derived resistance interval containing four genes including the candidate ling candidate gene because there is a known functional missense poly- genes Ctla4 and Icos (3, 4), a remarkable finding since human T1D is morphism (Gly169) Ͼ (Asp169) distinguishing the NOD and B10 associated with CTLA4 (5, 6). In addition to the human T1D association Nramp1 alleles. The NOD NRAMP1 protein is wild type and mediates with CTLA4, functional studies support the candidacy of Ctla4 as the protection from certain infectious diseases by contributing to the rapid diabetes gene in the Idd5.1 interval because the B10 allele of Ctla4 pro- acidification of the lysosome whereas the diabetes-resistant B10 duces more of the “ligand-independent” splice form of CTLA-4 NRAMP1 allotype is not functional (11). The likelihood of Nramp1 be- ing Idd5.2 is very high because a knockdown of the gene mimics the biological effect of the natural knockout (12). *Juvenile Diabetes Research Foundation/Wellcome Trust Diabetes and Inflammation Laboratory, Department of Medical Genetics, Cambridge Institute for Medical Re- The current study was initiated to test the hypothesis that Idd5.1/Ctla4 search, University of Cambridge, Cambridge, United Kingdom; and †Department of and Idd5.2/Nramp1 alone are sufficient to account for the diabetes pro- Pharmacology, Merck Research Laboratories, Rahway, NJ 07065 tection originally defined by the larger Idd5 locus containing both Idd5.1/ Received for publication September 11, 2006. Accepted for publication August 23, 2007. Ctla4 and Idd5.2. The unexpectedly high frequency of diabetes observed when resistance alleles at Idd5.1/Ctla4 and Idd5.2/Nramp1 were com- The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance bined revealed the existence of a third locus, Idd5.3, located between with 18 U.S.C. Section 1734 solely to indicate this fact. Idd5.1/Ctla4 and Idd5.2/Nramp1. This locus has been verified by the 1 This study was supported by National Institutes of Health Grant NIH P01 AI039671. development of Idd5.3 congenic strains. In addition, the previously re- The availability of NOD congenic mice through the Taconic Farms Emerging Models Program was supported by grants from the Merck Genome Research Institute, Na- ported strong interaction of the Idd5 and Idd3 protective alleles causing tional Institute of Allergy and Infectious Diseases, and the Juvenile Diabetes Research nearly complete protection from diabetes and insulitis (1, 13) was shown Foundation. L.S.W. and J.A.T. were supported by grants from the Juvenile Diabetes to require resistance alleles at Idd5.2 and Idd5.3, because Idd3 and Idd5.1/ Research Foundation and the Wellcome Trust, and L.S.W. was a Juvenile Diabetes Research Foundation/Wellcome Trust Principal Research Fellow. Ctla4 did not recapitulate the protection observed in mice having resis- 2 Address correspondence and reprint requests to Dr. Linda S. Wicker, Juvenile Di- tance alleles at both Idd3 and Idd5. abetes Research Foundation/Wellcome Trust Diabetes and Inflammation Laboratory, Another novel bicongenic strain consisting of Idd5.2/Nramp1 Department of Medical Genetics, Cambridge Institute for Medical Research, Well- come Trust/Medical Research Council Building, Addenbrooke’s Hospital, Cam- and Idd5.3 had an unexpectedly low frequency of diabetes, leading bridge, U.K. E-mail address: [email protected] to the discovery of a fourth Idd region on chromosome 1, Idd5.4. 3 Abbreviations used in this paper: Idd, insulin dependent diabetes; T1D, type 1 di- In the case of Idd5.4, it is the B10 allele, rather than the NOD abetes; liCTLA-4, “ligand-independent” splice form of CTLA-4; SNP, single nucle- allele, that confers susceptibility to T1D. We demonstrate that an otide polymorphism; AITD, autoimmune thyroid disease. interaction between the B10 Idd5.1/Ctla4 resistance allele and the Copyright © 2007 by The American Association of Immunologists, Inc. 0022-1767/07/$2.00 B10 Idd5.4 susceptibility allele exists and that the B10 Idd5.1/ www.jimmunol.org 8342 GENE INTERACTIONS IN TYPE 1 DIABETES FIGURE 1. Genetic intervals pres- ent in the Idd5 congenic strains referred to in this study. Filled regions are B10- Downloaded from derived or B6-derived segments of DNA for chromosomes 1 and 3, respec- tively, defined by the most centromeric and telomeric non-NOD allelic mark- ers. Open regions represent the region between the last non-NOD allelic marker and the first NOD allelic marker http://www.jimmunol.org/ at each boundary. Lines represent NOD-derived DNA. Vertical arrows designate the Idd5.1, Idd5.2, Idd5.3, and Idd5.4 regions. The Idd5.4 interval contains a segment that is NOD-derived due to a double recombination event (initially undetected) that occurred dur- ing the development of the R8 strain. The diagram is to scale. by guest on September 23, 2021 Ctla4 allele can, when present in different genetic contexts, provide ferred to are summarized in Fig. 1. An asterisk in Fig. 1 indicates the new potent, moderate, or undetectable protection from diabetes. Our study NOD.B10 chromosome 1 congenic lines developed specifically for the also has implications for the ongoing search and characterization of current study. The origins of all of the Idd5 strains in Fig. 1 can be traced to lines R8 or R2.