Systemic Lupus Erythematosus (SLE), a systemic autoimmune disorder, affects multiple organ systems resulting in significant morbidity and mortality. Lupus nephritis is a devastating complication of SLE, with an increased mortality and risk of progressive renal damage leading to end-stage renal disease (ESRD). To date, there remains no definitive pathway to identify the population of patients with lupus nephritis who are ultimately destined to ESRD. Identification of genes predicting ESRD risk in SLE would permit more vigorous treatment in this subgroup despite the potentially significant side effects. In our study of the genetics of lupus- prone mouse model NZM2328, we have identified separate genes controlling ANA and anti-dsDNA Ab production (Adaz1 on chromosome 4), and controlling both acute and chronic glomerulonephritis (GN) (Cgnz1 on chromosome 1 for controlling chronic GN and Agnz1 on chromosome 1, H-2 complex and Agnz2 on chromosome 17 for controlling acute GN). The phenotypes of NZM2328.Lc1 (Lc1) and Lc1 intrachromosomal recombinant congenic lines and NZM2328.Lc4 confirm our genetic analysis. A novel model for pathogenesis of SLE was proposed in which the genes contributing to lupus are classified into two classes - those affecting autoimmune responsiveness and those affecting end organ damage. These two classes of genes interact, resulting in clinical disease. The concept of genes controlling end organ resistance in SLE is novel. Additional data show that acute and chronic GN are under separate genetic control. A 1.34MB region on mouse chromosome 1 (the Cgnz1 locus) has been shown to contain gene(s) that confer resistance to the progression of acute GN (aGN) to chronic GN (cGN). In this competitive renewal application we wish to continue our research program to identify Cgnz1, the gene(s) within the 1.34Mb regions that confers end organ (kidney) susceptibility to damage.
Three specific aims are proposed:
Specific Aim 1 : To generate podocytes and tubular cell lines from NZM2328 and NZM2328.Lc1R27 (R27) to carryout in vitro gene deletion by the CRISPR/Cas method to identify candidate gene(s) that confer(s) resistance to apoptosis or play an important role in autophagy. Both podocytes and tubular cells will be used. These candidate genes will be targeted in Specific Aim 2;
Specific Aim 2 : To generate mutant lines with deficiency in targeted genes in (NZM2328XR27)F1 embryos by CRISPR/Cas and to generate homozygous mutants to validate susceptibility to end stage renal damage and to generate podocyte specific deletion mutants to demonstrate the gene(s) that exert(s) effects on podocytes;
and Specific Aim 3 : To identify candidate gene(s) on the human Cgnz1 1.6Mb locus (Hu Cgnz1) that determine the progression of progressive GN in lupus to ESRD. The results of the proposed studies will be validated and refined in future studies involving larger samples. We anticipate that they may provide biomarkers that are of prognostic value and utility for ESRD risk management. Thus the application will generate significant information regarding the pathogenesis of lupus GN and will have significant translational potentials.
This is a competitive renewal application to identify the gene(s) on mouse chromosome 1 that controls kidney's susceptibility to damage in lupus renal disease and the progression of the kidney disease to end stage renal disease. The findings in the mouse model will be translated to lupus patients with kidney disease. The results will provide genetic markers that identify patients who need more vigorous therapy so that the prospect of less lupus patients to progress to end stage renal disease that requires transplantation or dialysis can be realized.
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