Steroid Resistance in Nephrotic Syndrome

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DESCRIPTION: Steroid-resistant idiopathic nephrotic syndrome (SRINS) is an important cause of renal failure and end-stage renal disease in children. The cause of steroid resistance is unknown but evidence suggests that T cell dysfunction is responsible. Based on preliminary data on abnormal T cell NF-kB isoform composition in SRINS, the proposed project will identify the defects in T cell signaling mechanisms that lead to glucocorticoid resistance in patients with SRINS. The experiments will compare T cells from newly diagnosed SRINS patients with those from steroid-sensitive patients and healthy control children. Potential defects in the following specific signal transduction mechanisms, which may be associated with abnormal NF-kB function, will be evaluated: 1) Nuclear translocation of the glucocorticoid receptor (GCR) in response to dexamethasone exposure in vitro; 2) Increased production of STAT5 and interference of nuclear transfer of GCR by heterodimerizing with STAT5; 3) Dexamethasone-stimulated IL-2 production; 4) Induction of apoptosis in response to dexamethasone exposure. The methods will include standard T cell isolation, real time RT-PCR for gene expression, electrophoretic mobility shift assay for quantifying factors in nuclear vs cytoplasmic fractions, immunoprecipitation assay to detect complexed GCRs, as well as apoptosis