REGULATORS OF CALCINEURIN PATHWAYS AS DIAGNOSTIC AND THERAPEUTIC TARGETS FOR NEPHROTIC SYNDROME

肾病综合征和其他肾小球疾病是世界范围内慢性肾脏疾病的主要原因。 NS的分子机制还不完全清楚，这一知识上的重大差距是一个障碍 治疗NS患者和开发新的治疗方法。更全面地了解这些机制 基础NS对于确定稳健的非侵入性诊断工具和精确有效的治疗至关重要 选项.在初步的数据中，我们确定了钙调神经磷酸酶（CN）1型- NS组RCAN 1 -3分。我们发现，表达突变体RCAN 1的细胞显示CN活性升高， 和增加的细胞凋亡。这些表型通过CN的药理学抑制被拯救。我们的研究结果 提示RCAN基因的变异是NS的新的遗传原因，CN信号的调节剂可能 代表RCAN突变诱导的NS个体的靶向治疗，更常见的特发性NS 和其他肾小球疾病。尽管事实上，不受调节的CN激活是中枢神经系统疾病发病机制的核心。 多发性肾小球疾病过程和CN抑制剂（CNI）通常用于治疗， 由RCAN蛋白特异性调节的途径还不清楚。此外，只有约30-50%的患者 类固醇耐药NS将通过CNI治疗获得缓解，目前没有生物标志物 预测治疗反应，尽管CNI的主要副作用包括肾毒性。总体假设 RCAN基因的遗传缺陷通过降低足细胞活力引起CNI反应性NS， 可以通过靶向RCAN活性调节剂来改善的异常细胞骨架动力学。我们将测试 我们的假设通过以下目的：1）确定RCAN基因中的致病性变体对CNI的影响 2）确定介导NS患者异常治疗反应的分子机制， 由患者来源的iPSC足细胞和iPSC肾中的致病性RCAN变体引起的表型 类器官，以及3）鉴定可以在离体中挽救异常RCAN表型的靶向疗法 足细胞这些研究产生的数据将确定RCAN基因的遗传缺陷在疾病中的作用。 NS患者的发病机制和CNI治疗反应。此外，该研究将揭示足细胞信号传导 由于RCAN基因缺陷而失调的机制，并最终导致新的或 CNI治疗的替代疗法。

Nephrotic syndrome and other glomerular diseases are major causes of chronic kidney diseases world-wide. The molecular mechanisms of NS are not completely known, and this major gap in knowledge is an impediment to treating patients with NS and developing new treatments. A more complete understanding of the mechanisms underlying NS is critical for identification of robust non-invasive diagnostic tools and precise effective treatment options. In preliminary data, we identified pathogenic variants in the genes regulator of calcineurin (CN) types 1- 3 (RCAN1-3) in patients with NS. We showed that cells expressing mutant RCAN1 displayed elevated CN activity and increased apoptosis. These phenotypes were rescued by pharmacological inhibition of CN. Our findings suggest that variants in RCAN genes are novel genetic causes of NS, and that modulators of CN signaling may represent targeted therapy for individuals with NS induced by RCAN mutations, the more common idiopathic NS and other glomerular diseases. Despite the fact, that unregulated CN activation is central to the pathogenesis of multiple glomerular disease processes and CN inhibitors (CNIs) are often used for treatment, the signaling pathways regulated by RCAN proteins specifically are not well understood. Further, only ~30-50% of patients with steroid resistant NS will achieve remission with CNI treatment and there are currently no biomarkers to predict therapy response despite major side effects of CNI including nephrotoxicity. The overarching hypothesis of this study is that genetic defects in RCAN genes cause CNI responsive NS by reducing podocyte viability due to aberrant cytoskeletal dynamics that can be ameliorated by targeting modulators of RCAN activity. We will test our hypothesis through the following aims: 1) Determine the effect of pathogenic variants in RCAN genes on CNI therapy response in patients with NS, 2) Determine the molecular mechanisms mediating the aberrant phenotypes caused by pathogenic RCAN variants in patient derived iPSC podocytes and iPSC-kidney organoids, and 3) Identify targeted therapies that can rescue the aberrant RCAN phenotypes in ex-vivo podocytes. Data generated from these studies will define the role of genetic defects in RCAN genes in disease pathogenesis and CNI therapy response in patients with NS. In addition, the study will reveal podocyte signaling mechanisms that are dysregulated due to defective RCAN genes and ultimately lead to identification of novel or repurposed therapeutic alternatives to CNI treatment.