Characterization of ENTPD1 as a drug target in PXE

ENTPD1 作为 PXE 药物靶标的表征

• 批准号: 10790152
• 负责人: Koen van de Wetering
• 金额: $ 37.75万
• 依托单位: THOMAS JEFFERSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-20 至 2025-09-19
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10790152
• 关键词: ATP-Binding Cassette Transporters; Affect; Alleles; Animal Model; Arteries; Binding; Biological Availability; Biological Models; Blindness; Blood Circulation; Blood Vessels; Cardiovascular system; Cells; Characteristics; Chronic Kidney Failure; Circulation; Clinical; Complex; Connective and Soft Tissue; Cutaneous; Data; Deposition; Development; Diabetes Mellitus; Diagnosis; Diphosphates; Disadvantaged; Disease; Disease Progression; Dose; Drug Targeting; Environment; Extracellular Space; Extrahepatic; Eye; Eye Development; Factor V; Family; Functional disorder; Gastrointestinal Hemorrhage; Generations; Genes; Genetic; Goals; Half-Life; Hepatic; Hepatic Tissue; Hepatocyte; Heritability; Homeostasis; Human; Hypertension; In Vitro; Individual; Inherited; Injections; Intermittent Claudication; Liver; Mediating; Metabolism; Morbidity - disease rate; Mus; Mutation; Myocardial Infarction; Nucleotides; Oral Administration; Patients; Pharmacological Treatment; Plasma; Production; Progressive Disease; Proteins; Pseudoxanthoma Elasticum; Regimen; Replacement Therapy; Research; Residual state; Retina; Role; Skin; Solid; Stroke; Supplementation; Testing; Therapeutic; Transgenic Organisms; Visual Acuity; calcification; calcium phosphate; ecto-nucleotidase; effective therapy; extracellular; high risk; in vivo; in vivo Model; inhibitor; inorganic phosphate; member; mineralization; mouse model; novel therapeutic intervention; pharmacologic; plasma cell membrane glycoprotein PC-1; pre-clinical; prevent; prototype; tripolyphosphate

This research will focus on pseudoxanthoma elasticum (PXE), the prototype of heritable ectopic mineralization disorders. Aberrant calcium phosphate deposition in PXE results in characteristic cutaneous findings which signify the potential for development of ocular complications leading to loss of visual acuity and blindness, as well as cardiovascular involvement, including nephrogenic hypertension, intermittent claudication, bleeding from gastrointestinal arteries, early myocardial infarct and stroke. There is no effective treatment for PXE and the disease therefore progresses after diagnosis. PXE is caused by mutations in the ABCC6 gene which encodes ABCC6, an efflux transporter expressed primarily in the liver. Our group elucidated the pathophysiology underlying PXE, by showing that ABCC6 in hepatocytes mediates release of ATP into the blood circulation. Released ATP is extracellularly converted by the ecto-nucleotidase ENPP1 into 1 molecule of AMP and 1 molecule of the potent mineralization inhibitor inorganic pyrophosphate (PPi). PXE patients bearing defective ABCC6 have low PPi plasma concentrations, explaining their progressive calcification of soft connective tissues. Plasma PPi homeostasis is maintained through a complex network of proteins involved in ATP release, and ecto-nucleotidases metabolizing the released nucleotides. ENPP1 is crucial in this respect, as its activity underlies all PPi present in plasma. The ~40% of residual PPi present in plasma of PXE patients is formed out of ATP released by cells independent of ABCC6. Extracellular ATP is also subject to metabolism by other ecto- nucleotidases and the most important competitor of ENPP1 in the circulation is ENTPD1, which converts ATP into 1 molecule of AMP and 2 molecules of inorganic phosphate. Importantly, ENPP1 and ENTPD1 have opposing effects on extracellular PPi homeostasis and, consequently, ectopic calcification. In this study we propose to test the hypothesis that inhibition of ENTPD1 enhances extracellular PPi formation and prevents ectopic calcification in PXE patients We have developed two Specific Aims to test our hypothesis: (1) Thoroughly characterize how competition between ENPP1 and ENTPD1 affects extracellular PPi homeostasis in vitro and (2) Determine the effect of ENTPD1 on plasma PPi concentrations and ectopic calcification in Abcc6-/- mice in vivo. These plans are based on solid preliminary data, and they take advantage of a well-characterized mouse model developed and characterized in our department – the Abcc6-/- mouse –, which recapitulates the clinical, histopathologic, ultrastructural and genetic features of PXE in humans. Collectively, our state-of-the-art studies utilizing both in vitro and in vivo model systems are expected to provide critical preclinical information of the therapeutic potential of ENTPD1 inhibition to restore plasma PPi levels in PXE, with subsequent inhibition of ectopic calcification. Our findings are expected to not only inform development of pharmacologic treatments for PXE, but also for other ectopic calcification disorders, for which no effective or specific therapy is currently available.

这项研究将侧重于假阳性瘤（PXE），这是可遗传异位矿化的原型 疾病。 PXE中异常磷酸钙沉积会导致皮肤皮肤的特征性发现，这些发现 表示眼睛并发症发展的潜力导致视力和失明的丧失，为 以及心血管受累，包括肾病高血压，间歇性lau不休，出血 胃肠道动脉，早期心肌梗塞和中风。没有有效的PXE治疗 因此，疾病在诊断后进展。 PXE是由编码的ABCC6基因中的突变引起的 ABCC6，一种主要在肝脏中表达的外排转运蛋白。我们的小组阐明了病理生理学 PXE的基础，通过显示肝细胞中的ABCC6介导ATP释放到血液循环中。 释放的ATP被骨外核苷酸酶ENPP1细胞外转化为1分子的AMP和1个分子 有效矿化抑制剂无机焦磷酸盐（PPI）的分子。 PXE患者患有缺陷 ABCC6的PPI血浆浓度较低，解释了它们对软结缔组织的进行性计算。 血浆PPI稳态是通过涉及ATP释放的复杂蛋白质网络维护的，并且 核苷酸核苷酸酶代谢释放的核苷酸。 ENPP1在这方面至关重要，因为它的活动 基础血浆中存在的所有PPI。 PXE患者血浆中存在约40％的残留PPI是形成的 由细胞释放的ATP独立于ABCC6。细胞外ATP也受到其他外生的代谢 循环中ENPP1的核苷酸酶和最重要的竞争者是ENTPD1，它转换ATP 进入1分子的AMP分子和2个分子的无机磷酸盐。重要的是，ENPP1和ENTPD1具有 对细胞外PPI稳态的影响，因此是生态钙化。在这项研究中，我们 测试抑制ENTPD1的假设的提议增强了细胞外PPI的形成和 防止PXE患者的异位计算我们开发了两个特定的目的来检验我们的假设： （1）彻底表征ENPP1和ENTPD1之间的竞争如何影响细胞外PPI 体外稳态，（2）确定ENTPD1对等离子体PPI浓度和Ecopic的影响 ABCC6 - / - 小鼠体内的钙化。这些计划基于可靠的初步数据，它们会利用 在我们的部门开发和表征的特征良好的鼠标模型-ABCC6 - / - 鼠标 - ，，， 这概括了人类PXE的临床，组织病理学，超微结构和遗传特征。 总体而言，我们利用体外和体内模型系统的最先进的研究有望提供 ENTPD1抑制在恢复血浆PPI水平的治疗潜力的关键临床前信息 PXE，随后抑制生态钙化。我们的发现不仅会为开发提供信息 PXE的药物治疗，以及其他生态钙化障碍，无效或 目前可以使用具体的疗法。