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* Division of Rheumatology and Immunology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15261;
Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261; and
Juvenile Diabetes Research Foundation/Wellcome Trust Diabetes and Inflammation Laboratory, Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
NOD.Idd3/5 congenic mice have insulin-dependent diabetes (Idd) regions on chromosomes 1 (Idd5) and 3 (Idd3) derived from the nondiabetic strains B10 and B6, respectively. NOD.Idd3/5 mice are almost completely protected from type 1 diabetes (T1D) but the genes within Idd3 and Idd5 responsible for the disease-altering phenotype have been only partially characterized. To test the hypothesis that candidate Idd genes can be identified by differential gene expression between activated CD4+ T cells from the diabetes-susceptible NOD strain and the diabetes-resistant NOD.Idd3/5 congenic strain, genome-wide microarray expression analysis was performed using an empirical Bayes method. Remarkably, 16 of the 20 most differentially expressed genes were located in the introgressed regions on chromosomes 1 and 3, validating our initial hypothesis. The two genes with the greatest differential RNA expression on chromosome 1 were those encoding decay-accelerating factor (DAF, also known as CD55) and acyl-coenzyme A dehydrogenase, long chain, which are located in the Idd5.4 and Idd5.3 regions, respectively. Neither gene has been implicated previously in the pathogenesis of T1D. In the case of DAF, differential expression of mRNA was extended to the protein level; NOD CD4+ T cells expressed higher levels of cell surface DAF compared with NOD.Idd3/5 CD4+ T cells following activation with anti-CD3 and -CD28. DAF up-regulation was IL-4 dependent and blocked under Th1 conditions. These results validate the approach of using congenic mice together with genome-wide analysis of tissue-specific gene expression to identify novel candidate genes in T1D.
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 with 18 U.S.C. Section 1734 solely to indicate this fact.
1 W.M.R. was supported by National Institutes of Health (NIH) National Institute of Diabetes and Digestive and Kidney Diseases 60714 and NIH RFA A102-006. L.S.W. is a Juvenile Diabetes Research Foundation (JDRF)/Wellcome Trust Principal Research Fellow and the research in the laboratory of L.S.W. for this study was also supported by NIH P01 AI039671. The availability of NOD congenic mice through the Taconic Farms Emerging Models Program has been supported by grants from the Merck Genome Research Institute, National Institute of Allergy and Infectious Diseases, and the JDRF.
2 Address correspondence and reprint requests to Dr. William M. Ridgway, Division of Rheumatology and Immunology, School of Medicine, University of Pittsburgh, S725 Biomedical Science Tower, 200 Lothrop Street, Pittsburgh, PA 15261. E-mail address: ridgway2{at}pitt.edu
3 Abbreviations used in this paper: T1D, type 1 diabetes; Idd, insulin-dependent diabetes; SNP, single nucleotide polymorphism; DAF, decay-accelerating factor; Ct, cycle threshold; ACADL, acyl-coenzyme A dehydrogenase, long chain; SAPE, streptavidin-PE.
4 The online version of this article contains supplemental material.
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