E expression is needed on both bone marrow derived cells and thymic epithelium to increase IL-4 production and achieve protection in NOD bone marrow chimeras

Effect of X- and Y-box deletions on the development of diabetes in H-2Ealpha-chain transgenic nonobese diabetic mice

The development of type 1 diabetes in nonobese diabetic (NOD) mice is influenced by major histocompatibility complex (MHC) class II genes. The NOD-E transgenic mouse, which expresses H2-E as a result of the introduction of an Ead gene, is protected from development of type 1 diabetes. While the mechanism of protection remains unclear, the effect has been regarded as a model system for MHC protection from autoimmunity. We have investigated the effect of deletions of the Ea promoter region, which, in turn, affect H2-E expression patterns in transgenic NOD mice. We have constructed transgenic NOD mice where the X (DeltaX) and Y (DeltaY) boxes of the Ead gene have, respectively, been functionally deleted. Previous reports, using X- or Y-box-deleted H2-E transgenic mice, made by crossing the appropriate transgenes onto the NOD background from C57BL/6 transgenic mice, indicated that promoter mutation abrogated the H2-E-mediated protection seen in NOD-E. The NOD DeltaX and NOD DeltaY transgenic mice generated in the present study differ in susceptibility to diabetes from wild-type NOD mice. NOD DeltaY1 animals are protected from diabetes development, while DeltaX mice remain susceptible, albeit to a lesser extent than the parental NOD strain.

Expression, genomic structure and mapping of the thymus specific protease prss16: a candidate gene for insulin dependent diabetes mellitus susceptibility

PRSS16 is a serine protease specifically expressed by epithelial cells in the thymic cortex. The human gene is encoded on 6p21.3-p22 where recent linkage analysis has identified an association with insulin dependent diabetes mellitus (IDDM) susceptibility independent of HLA-DR3. To further investigate its potential role in autoimmunity, we characterized the mouse orthologue, Prss16. The genomic structure of Prss16 shows conservation with the human gene in size, number of exons and chromosomal location. Mapping of Prss16 places it on mouse chromosome 13 centromeric of thesatin locus. This region is comparable to the PRSS16 region on human chromosome 6 and has also been linked to quantitative trait locus for IDDM in the nonobese diabetic mouse. Similar to the human gene, Prss16 expression is highly specific in the mouse with expression limited to the cortical thymic epithelium. Notably, embryonic expression coincides with population of the thymic anlage with T-cell precursors and initiation of T-cell development. We also show that NOD and New Zealand Black mice, which have a disrupted thymic architecture and autoimmune phenotype, have lower levels of Prss16 expression compared to C57BL/6 mice. These findings support the role of Prss16 in T-cell development and susceptibility to autoimmunity in the mouse.