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的分子机制尚不完全清楚，这一认识上的重大差距是一个障碍 到治疗NS患者和开发新的治疗方法。对机制有了更全面的了解 潜在的NS对于识别强大的非侵入性诊断工具和精确有效的治疗至关重要 选择。在初步数据中，我们发现了钙调神经磷酸酶(CN)1型基因调控的致病变异。 3(RCAN1-3)在NS患者中。我们发现，表达突变型RCAN1的细胞显示出较高的CN活性 并增加了细胞凋亡率。CN的药理抑制挽救了这些表型。我们的发现 提示rcan基因的变异是NS的新的遗传原因，CN信号的调节器可能 代表针对rcan突变导致的NS患者的靶向治疗，更常见的是特发性NS 以及其他肾小球疾病。尽管如此，未受调控的CN激活是致病机制的核心 多个肾小球疾病过程和CN抑制剂(CNI)经常用于治疗，信号转导 受rcan蛋白特异性调控的通路还不是很清楚。此外，只有~30%-50%的患者 具有类固醇抗药性的NS将通过CNI治疗实现缓解，目前还没有生物标志物可以 尽管CNI的主要副作用包括肾毒性，但仍可预测治疗反应。最重要的假设 这项研究的主要内容是rcan基因的遗传缺陷通过降低足细胞存活率而引起CNI反应性NS。 涉及可以通过靶向rcan活性调节器来改善的异常细胞骨架动力学。我们将测试 我们的假设有以下几个目的：1)确定rcan基因致病变异对CNI的影响 肾病综合征患者的治疗反应，2)确定异常的分子机制 致病rcan变异引起的IPSC足细胞和IPSC肾组织表型 有机化合物，以及3)确定靶向治疗，可以在体外挽救异常的rcan表型 足细胞。这些研究产生的数据将确定rcan基因中的遗传缺陷在疾病中的作用。 肾病综合征患者的发病机制及CNI治疗反应。此外，这项研究还将揭示足细胞信号 由于rcan基因缺陷而导致调控失调的机制，并最终导致新的或 改变了CNI治疗的治疗替代方案。

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.