Decoding reno-protective mechanisms in mouse Pkhd1 models: Implications for ARPKD therapeutics

解码小鼠 Pkhd1 模型中的肾脏保护机制：对 ARPKD 治疗的影响

基本信息

批准号：
10170340
负责人：
LISA MARIE GUAY-WOODFORD
金额：
$ 39.27万
依托单位：
CHILDREN'S RESEARCH INSTITUTE
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-01 至 2025-04-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10170340
关键词：
ATP12A gene Address Affect Attenuated Autosomal Dominant Polycystic Kidney Autosomal Recessive Polycystic Kidney Biliary Binding C-terminal Cell membrane Cyst Cystic Kidney Diseases Data Disease Duct (organ) structure Engineering Exons Financial compensation Foundations Gene Expression Gene Family Genes Genetic Genetic Models Genetic Transcription Human Infant Integral Membrane Protein Kidney Kidney Diseases Liver Fibrosis MYC Family Protein Messenger RNA Modeling Mus Muscle Mutant Strains Mice Mutation Nuclear Outcome Pathogenesis Pathway interactions Patients Perinatal Phenocopy Phenotype Phylogenetic Analysis Proteins Regulation Renal function Research Role Severity of illness Survivors Testing Therapeutic Transcriptional Regulation Translating United States base disease phenotype experimental study human disease in vivo infancy insight loss of function mouse genetics mutant notch protein novel therapeutic intervention overexpression promoter protein protein interaction renal epithelium therapeutic target trafficking

项目摘要

PROJECT SUMMARY There are ~1,500 patients in the United States with autosomal recessive polycystic kidney disease (ARPKD; MIM 173900), a hepatorenal fibrocystic disorder characterized by enlarged kidneys with innumerable collecting duct cysts and progressive loss of renal function. Essentially all cases of ARPKD can be attributed to mutations in PKHD1, which encodes a single-pass transmembrane protein, fibrocystin/polyductin (FPC). We currently have very little insight into the pathogenesis of human ARPKD and thus, treatment is largely supportive. Striking species-specific differences in the PKHD1/Pkhd1 renal phenotype may offer important insights into disease mechanisms. While human patients with either missense or truncating PKHD1 mutations have severe renal cystic disease, mouse Pkhd1 models with engineered truncating mutations (and presumably loss of FPC function) express minimal or no renal disease. Our preliminary studies reveal that while MYC is overexpressed in human ARPKD kidneys, Myc is not overexpressed in mouse Pkhd1 kidneys. In previous studies, we have shown that FPC undergoes Notch-like processing with cleavage of the carboxy terminus (FPC-CTD) from the plasma membrane and nuclear trafficking. Here, we demonstrate that the mouse FPC-CTD binds directly to the Myc P1 promoter and increases Myc expression. Based on these findings, we hypothesize that mouse renal epithelia can compensate for the loss of FPC-CTD function through reno-protective mechanisms and that species-specific, FPC-CTD regulation of Myc expression is central to this reno-protection. We speculate that while these mechanisms are not normally operative in human renal epithelia, they may identify new opportunities for therapeutic targeting in human ARPKD renal disease. We propose two specific aims to test our hypothesis: (1) define how the FPC-CTD regulates Myc/MYC expression in mouse and human renal epithelia and determine whether disruption of the proposed regulatory circuits is a central driver of renal cystogenesis; and (2) compare the FPC-CTD nuclear interactome in mouse and human renal epithelia and test whether differences in transcriptional targets identifies reno-protective pathways in mouse kidneys. Our studies will advance the field by sequentially addressing the transcriptional role of FPC-CTD. Specifically, we will: 1) determine mouse Pkhd1 models; how FPC-CTD related Myc transcriptional regulation contributes to reno-protection in and 2) identify putative mechanisms that allow mouse renal epithelia to compensate for the loss of FPC-CTD nuclear function. Moving forward, these data will lay the foundation for translating mouse reno-protective mechanisms into novel, therapeutic strategies that attenuate human PKHD1-related renal cystic disease.

项目概要美国约有 1,500 名常染色体隐性遗传性多囊肾病 (ARPKD；ARPKD； MIM 173900），一种肝肾纤维囊性疾病，其特征是肾脏增大并伴有无数集合导管囊肿和肾功能进行性丧失。基本上所有 ARPKD 病例均可归因于突变 PKHD1 编码单次跨膜蛋白纤维囊藻蛋白/多聚导管蛋白 (FPC)。我们目前有对人类 ARPKD 发病机制的了解很少，因此治疗主要是支持性的。 PKHD1/Pkhd1 肾脏表型的显着物种特异性差异可能为以下方面提供重要见解：疾病机制。虽然具有错义或截短 PKHD1 突变的人类患者患有严重的肾囊性疾病，具有工程截短突变的小鼠 Pkhd1 模型（可能还丢失了 FPC）功能）表达轻微或无肾脏疾病。我们的初步研究表明，虽然 MYC 过度表达在人类 ARPKD 肾脏中，Myc 在小鼠 Pkhd1 肾脏中并未过度表达。在之前的研究中，我们有结果表明，FPC 经历了类似 Notch 的加工，将羧基末端 (FPC-CTD) 从质膜和核运输。在这里，我们证明小鼠 FPC-CTD 直接结合 Myc P1 启动子并增加 Myc 表达。基于这些发现，我们假设小鼠肾上皮可以补偿 FPC-CTD 的损失通过肾脏保护机制发挥作用，并且物种特异性、FPC-CTD 对 Myc 表达的调节是这次修复保护的核心。我们推测，虽然这些机制在人类中通常不起作用肾上皮细胞，他们可能会发现人类 ARPKD 肾脏疾病治疗靶向的新机会。我们提出两个具体目标来检验我们的假设：（1）定义FPC-CTD如何调节Myc/MYC表达在小鼠和人肾上皮细胞中，并确定所提出的调节电路的破坏是否是一个肾囊肿发生的中心驱动因素； (2) 比较小鼠和人类的 FPC-CTD 核相互作用组肾上皮细胞并测试转录靶点的差异是否能识别小鼠的肾保护途径肾脏。我们的研究将通过依次解决 FPC-CTD 的转录作用来推进该领域的发展。具体来说，我们将：1）确定鼠标 Pkhd1 型号； FPC-CTD 相关的 Myc 转录调控如何有助于肾病保护 2）确定允许小鼠肾上皮细胞补偿的假定机制 FPC-CTD核功能丧失。展望未来，这些数据将为翻译鼠标奠定基础肾脏保护机制成为减轻人类 PKHD1 相关肾囊肿的新型治疗策略疾病。