Role of SF Gene Cluster in Autoimmunity

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EXCEED THE SPACE PROVIDED. The Slel congenic interval contains a cluster of genes that initiate the autoimmune cascade leading to fatal lupus in the NZM2410 mouse. Positional cloning analysis has identified a seven gene cluster on mouse chromosome 1 containing the CD150 family of genes (CD48, Lyl08, Csl, CD84, CD244, CD150, CD229) as causative for a breach in tolerance to nuclear antigens. These genes modulate activation thresholds and effector function in many lymphocyte lineages. Our comparison of B6 and B6.Slelb revealed the existence of several structural and regulatory polymorphisms in this gene family. We propose to characterize the impact of these polymorphisms on immune function as follows: 1) To assess the expression of the CD150/CD2 family of genes in vivo. Expression profiles of this gene cluster will be determined in various lymphoctye populations isolated from B6 and B6.Slelb mice prior to and following disease onset. This will be accomplished by a combination of flow cytometry, RT-PCR analysis and the generation of transgenic mice with reporter constructs under the control of regulatory elements of individual CD150 member genes. 2) To characterize the impact of CD150 family gene polymorphisms on lymphocyte function. Functional studies will be performed on B and T cells isolated from B6 and B6.Slelb mice. This will allow us to determine the impact of polymorphisms at the CD150 gene cluster on lymphocyte function in an otherwise genetically identical background. 3) To create an animal model to assess CD150 family member function. The goal of this aim is to generate a mouse strain in which the entire CD150 gene cluster has been deleted using Cre recombinase and flanking LoxP sites. These mice will be essential to study the role of this gene family in lymphocyte function in vivo. In addition, these mice will be used to reconstitute CD150 family member expression by BAC transgenic rescue to assess the role of individual or combinations of CD150 family members in immune function. 4) To assess the impact of the CD150 cluster polymorphisms on autoimmunity. We have developed B6-derived (autoimmune resistant) and 129Sv-derived (autoimmune prone) BAC contigs spanning the CD150 gene cluster for the generation of BAC transgenic mice. These will be used in combination with the CD150 cluster deletion mouse strain to definitively characterize the autoimmune potential of these genes singly or in combination. PERFORMANCE SITE ========================================Section End===========================================