Idd3^CAST/EiJ
QTL Variant Detail

Summary

• QTL variant: Idd3^CAST/EiJ
• Name: insulin dependent diabetes susceptibility 3; CAST/EiJ
• MGI ID: MGI:3764464
• QTL: Idd3 Location: unknown Genetic Position: Chr3, cM position of peak correlated region/allele: 29.17 cM
• QTL Note: genome coordinates based on the marker associated with the peak LOD score

Variant origin

• Strain of Specimen: CAST/EiJ

Variant description

• Allele Type: QTL
• Mutation: Undefined
• Mutation details: This allele confers susceptibility to type 1 diabetes compared to C57BL/6J and CZECHI/EiJ. Diabetes onset and incidence among mice of this strain is reported to be similar to NOD/MrkTac. (J:120349)
• Inheritance: Recessive

Notes

Candidate Genes

J:86885

Congenic animals were created to observe the effect of diabetes QTL Idd1 on mouse Chromosome 17. The congenic NOD.CTS-H2 carries CTS-derived DNA at the H2 locus, which is part of Idd1, on an NOD diabetes-susceptible genetic background. Parental strain CTS is diabetes resistant but shares the same H2 alleles as NOD. Interestingly the NOD.CTS-H2 congenic is susceptible to diabetes but with lower incidence compared to NOD. Authors state that the H2 locus is responsible for the diabetes susceptible effect ofIdd1 but does not explain it entirely. A closely linked but distinct QTL, Idd16 at 18 cM, may also contribute to the NOD susceptible phenotype. A candidate gene for Idd16 is Tnf (19.06 cM). Haplotype analysis was performed to assess the candidacy of Tnf.The non-diabetic inbred strain NON shares the same Tnf alleles as the diabetic strain NOD. The congenic NON.NOD-H2 carryies NON-derived DNA around the H2 locus (including Tnf) on a NOD genetic background and is diabetes susceptible. This data supports the candidacy of Tnf for Idd16.

To study the Idd3 candidate gene, Il2 (19.2 cM on mouse Chromosome 3), a congenic line was constructed. NOD.IIS-Il2 carries ISS-derived DNA at Il2 on an NOD diabetes susceptible background. Parental strain ISS is resistant to diabetes but shares alleles with NOD at Il2. The congenic is phenotypically indistinguishable from the NOD parental indicating that the NOD alleles at Il2 exert an effect on diabetes susceptibility. Another candidate gene for Idd3 is Il21. Il21 is closelylinked to and forms a haplotype with Il2, making Il21 a strong candidate for Idd3.

Idd10 maps to 48.5 cM on mouse Chromosome 3. Fcgr1 (45.2 cM) has been identified as a possible candidate gene for Idd10. Sequence analysis revealed 17 amino acid differences between NOD and C57BL/10 in addition to deletion of 75% of the cytoplasmic tail. A congenic line carrying diabetes resistant ISS-derived DNA at Idd10 on an NOD diabetes susceptible background was constructed. However, the NOD.IIS-Idd10 congenic is notsusceptible to diabetes, therefore excluding Fcgr1 from the candidate gene list. Further analysis of the Idd10 locus revealed 3 multiply linked loci: Idd10, Idd17, and Idd18.

Mapping and Phenotype information for this QTL, its variants and associated markers

J:52572

A locus for experimental autoimmune encephalomyelitis (EAE) resistance colocalizes with a locus for diabetes resistance, Idd3, to a 0.15 cM interval on mouse chromosome 3 at approximately 19.2 cM. NOD congenic lines were constructed carrying C57BL/6-derived (resistant) alleles on a NOD (susceptible) background at Idd3 (NOD.B6-Idd3 line) and at Idd17, Idd10, and Idd18 (NOD.B6-Idd17, Idd10, Idd18 line). NOD.B6-Idd3 animals carry C57BL/6-derived alleles from D3Nds36 to D3Nds34 and are resistant to diabetes and exhibit mild EAE symptoms. NOD.B6-Idd17, Idd10, Idd18 animals carry C57BL/6-derived alleles from D3Mit51 to D3Mit124 and are susceptible to both diabetes and EAE. The 0.15 cM NOD.B6-Idd3 interval contains Il2 (interleukin 2), a candidate gene for bothdiseases. Investigation of Il2 revealed differences in the sequence and glycosylation status of Il2 between C57BL/6 and NOD strains.

J:13557

123 polymorphic markers were screened in a backcross population of NOD/Lt x (B10.NOD-H2^g7 x NOD/Lt)F1 animals to identify QTLs associated with susceptibility to insulin dependent (type 1) diabetes. 106 diabetic backcross animals and 190 non-diabetic backcross animals were used in this study. Parental strain NOD/Lt spontaneously develops type 1 diabetes whereas parental strain B10.NOD-H2^g7 is resistant.

Three novel diabetes susceptibility QTLs were identified. Idd7 mapped to 4.5 cM on mouse Chromosome 7 near D7Nds6, Idd8 mapped to 2.5 cM on mouse Chromosome 14 near D14Nds1, and Idd10 mapped to 45 cM on mouse chromosome 3 near D3Nds7, D3Nds11, and D3Nds8. Idd7 and Idd8 are associated with insulitis and diabetes susceptibility. Homozygosity for NOD/Lt-derived alleles confers resistance to diabetes at Idd7 and Idd8 indicating a dominant susceptible effect of the C57BL/10-derived allele. Idd10 also shows linkage to insulitis and diabetes susceptibility.

Several previously identified QTLs were detected in this study:

Idd3 mapped to 28 cM on mouse Chromosome 3 near D3Nds1 in linkage to diabetes susceptibility and insulitis. Sequence analysis of candidate gene Il2 revealed several amino acid difference between NOD/Lt and C57BL/10.

Idd4 mapped to 43.8 cM on mouse Chromosome 11 near D11Nds1 in linkage to diabetes susceptibility.

Idd5 mapped to 19.5 cM on mouse Chromosome 1 near D1Nds6 in linkage to diabetes susceptibility and insulitis.

Idd6 mapped to 71.2 cM on mouse Chromosome 6 near D6Mit14 in linkage todiabetes susceptibility.

J:99466

From a previous study, the NOD-derived diabetes susceptibility QTL Idd3 at 19.2 cM on mouse Chromosome 3 is localized to a 0.15 cM interval between D3Nds36 and D3Nds76. A strong candidate gene named Il2 (19.2 cM) is located in this interval. In order to ascertain the diabetes susceptibility effect of an NOD-derived Il2 allele, the authors looked at NOD-related inbred strains. Four inbred strains (CTS, IIS, IOI, and NSY) shared the same Il2 allele with NOD. Among these, only inbred strain IIS contained flanking DNA different from NOD.

Preliminary data from Il2 congenic animals derived from an IIS donor and NOD recipient indicate that the NOD.IIS-Il2 congenic is just as susceptible to diabetes as background strain NOD. These preliminary results suggest that NOD-derived Il2 is responsible for the diabetes susceptible effect of Idd3.

J:61763

The Idd3 locus on mouse Chromosome 3 was narrowed to a 145 kb interval using a combination of congenic strain haplotype analysis, SNP haplotype analysis, and contig mapping. The Idd3 interval is most likely located between D3Nds6 (19.2 cM) and SNP 81.3. Il2 is a strong candidate mapping to this interval. Sequence analysis of the Il2 promoter region between diabetes susceptible and resistant mouse strains revealed 2 polymorphisms in non-regulatory regions. Furthermore, Il2 expression levels did not differbetween diabetes susceptible and resistant strains. A serine to proline amino acid substitution at residue 6 of the Il2 protein is associated with increased glycosylation and diabetes susceptibility. This non-conservative polymorphism may account for theeffect of Idd3.

J:108210

Idd3 is a diabetes susceptibility QTL mapping to a 145 kb interval on mouse Chromosome 3 around 19.2 cM. Il2 colocalizes with Idd3 and has been suggested as a candidate gene. Authors compared electrophoretic mobility of IL-2 proteins from diabetes-susceptible strain NOD and diabetes-resistant congenic strain NOD.B6-Idd3 using SDS-PAGE and Western blot analysis. The NOD IL-2 electrophoretic pattern was relatively homogeneous showing a 21-22 kDa specicies with a smaller minor species whereas the C57BL/6J IL-2 (from NOD.B6-Idd3) electrophoretic pattern was heterogeneous with several major species between 17-19 kDa.

Furthermore, analysis of diabetes susceptible strain 129 (Taconic farms) revealed a single amino acid substitution at position 4 of the Il2 gene compared to the NOD allele. Authors constructed a diabetes susceptible congenic line named NOD.129-Idd3, which carries 129-derived DNA from D3Mit93 (13.8 cM) to D3Mit65 (23.3 cM). A homogeneous electrophoretic mobility pattern was observed with IL-2 protein from NOD.129-Idd3 animals. Authors postulate that diabetes resistance at Idd3 is associated with a heterogeneous IL-2 electrophoretic pattern while diabetes susceptibility at Idd3 is associated with a homogeneous IL-2 electrophoretic pattern. Differences in protein mobility may be due to variation in IL-2 glycosylation between the different strains.

In addition, IL-2 protein from activated spleen cells of NOD, NOD.B6-Idd3, and NOD.129-Idd3 animals were able to stimulate cell proliferation of IL-2 dependent cell lines in vitro. Therefore, the diabetes phenotype may be independent of IL-2 dependent cell proliferation.

J:106844

Loci linked to Ctla4 expression in CD4+CD69+ and CD8+CD69+ T-cells were mapped in 196 (NOD x C57BL/6)F2 intercross animals. 119 microsatellite markers were used for the genome scan. Nonobese diabeteic parental strain NOD exhibits defective Ctla4 expression in CD3 activated T-cells compared to parental strain C57BL/6.

Ctex (Ctla4 expression) mapped to distal mouse Chromosome 1 near D1Mit353 (92.3 cM; LOD=6.5) in linkage to Ctla4 expression in CD4+ T-cells. This locus also shows significant linkage to Ctla4 expression in CD8+CD69+ T-cells with LOD=9.8. The Ctex QTL interval spans a 21 cM region between D1Mit104 (79 cM) and D1Mit403 (100 cM). Ctex was confirmed in a congenic line carrying C57BL/6-derived DNA from D1Mit411 (18.5 cM) to D1Mit403 (100 cM) ona NOD genetic background. The congenic interval includes Idd5a (38.5 cM), Idd5b (41 cM), and Ctex. Congenic animals exhibit intermediate or fully restored Ctla4 expression in CD4+ and CD8+ T-cells thus confirming the effect of Ctex. This observation suggests that NOD-derived alleles at Ctex confer decreased Ctla4 expression whereas C57BL/6-derived alleles at Ctex restores Ctla4 expression in activated T-cells. Previously identified QTL mapping near Ctex include Mbis1 (81.6 cM), Tcdel1, and Nktcn1 (87.9 cM). Potential candidate genes for Ctex include Cd247 (formerly Cd3z; 87.2 cM), Pdcd1, and Bcl2 (59.8 cM). The Idd5a/Idd5b region appears to influence in vitro ICOS expression in activated NOD spleen T-cells. Inbred strain NOD exhibits increased ICOS expression compared to C57BL/6. Congenic animals carrying C57BL/6-derived alleles at Idd5a and Idd5b on an NOD genetic background express ICOS at levels similar to the C57BL/6 donor.

Suggestive linkage to Ctla4 expression in CD4+CD69+ and CD8+CD69+ T-cells mapped to mouse Chromosome 3 between D3Mit164 (2.4 cM) and D3Mit95 (22 cM). This locus contains previously identified diabetes QTL Idd3 (19.2 cM). This locus was confirmed in congenic animals carrying C57BL/6-derived DNA from D3Mit167 (16.5 cM) to D3Mit94 (22 cM), which encompasses Idd3, on a NOD genetic background. Congenic animals exhibit intermediate or fully restored Ctla4 expression in CD4+ and CD8+ T-cells thus confirming the effect of Idd3. This observation suggests that NOD-derived alleles at Idd3 confer decreased Ctla4 expression whereas C57BL/6-derived alleles at Idd3 restores Ctla4 expression in activated T-cells. Il2 (19.2 cM) is a potential candidate gene for Idd3. Addition of recombinant IL2 to activated NOD-derived spleen cultures increased the percentage of Ctla4-expressing CD8+ T-cells but did not increase the percentage of Ctla4-expressing CD4+ T-cells.

References

• Original: J:120349 Yamanouchi J, et al., Interleukin-2 gene variation impairs regulatory T cell function and causes autoimmunity. Nat Genet. 2007 Mar;39(3):329-37
• All: 1 reference(s)