Project 4 - Mechanisms of pyrophosphate dysregulation

项目 4 - 焦磷酸盐失调的机制

• 批准号: 10628931
• 负责人: JOSE LUIS MILLAN
• 金额: $ 68.44万
• 依托单位: MEDICAL COLLEGE OF WISCONSIN
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2028-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10628931
• 关键词: Address; Affect; Age related macular degeneration; Aging; Alkaline Phosphatase; Alzheimer' s Disease; Ameloblasts; Area; Arteries; Atherosclerosis; Biochemical Process; Blood Vessels; Bone Diseases; Brain; Bruch' s basal membrane structure; Bulla; Cell physiology; Cells; Characteristics; Chondrocytes; Choroid; Clinical; Data; Dental; Deposition; Diphosphates; Disease; Drusen; Dysplasia; Endothelium; Extracellular Matrix; Eye; Functional disorder; Genes; Goals; Human; Hydroxyapatites; Hypophosphatasia; Inflammation; Inorganic Phosphate Transporter; Lead; Medial; Mediating; Medical; Minerals; Modeling; Molecular; Mus; Mutation; Odontoblasts; Osteoblasts; Osteomalacia; Pathologic; Pathway interactions; Phosphorylcholine; Physiological; Prevention; Production; Pseudoxanthoma Elasticum; Rickets; Risk Factors; Role; Structure of retinal pigment epithelium; Testing; Tissues; Tooth structure; Up-Regulation; Vascular calcification; Vesicle; arterial calcification of infancy; bone; calcification; calcification inhibitor; design; druggable target; extracellular; extracellular vesicles; genetic manipulation; in vivo; inorganic phosphate; insight; macula; mineralization; mouse model; multidisciplinary; normal aging; novel; pharmacologic; prevent; promoter; pyrophosphatase; skeletal; synergism

PROJECT 4 SUMMARY Mechanisms of pyrophosphate dysregulation. Hydroxyapatite deposition in bones and teeth is a carefully orchestrated biochemical process aimed at balancing the concentrations of inorganic pyrophosphate (PPi), a potent calcification inhibitor, and the local concentrations of phosphate (Pi), a calcification promoter, to establish a proper PPi/Pi ratio to enable regulated tissue mineralization to take place. While we have a good understanding of what molecules control physiological skeletal and dental mineralization, limited data exists as to whether alterations in those same mechanisms lead to ectopic calcification in the eyes, brain, and vasculature in diseases of aging such as age-related macular degeneration (AMD), Alzheimer's disease (AD) and atherosclerosis. AMD is clinically characterized by the presence of extracellular deposits known as drusen, located between the retinal pigment epithelium (RPE) and the choroidal microvasculature in the area known as the Bruch’s membrane in the macular region. Drusen is also observed in the normal aging eye associated with local inflammation, and the presence of a high number of large drusen in the macular region is a significant risk factor for developing AMD. While there are no murine models that fully reflect the pathophysiology of human AMD, the Abcc6-/- and the Enpp1-/- mouse models of pseudoxanthoma elasticum (PXE) and generalized arterial calcification of infancy (GACI) respectively, manifest not only vascular and brain calcification but also calcifications in the eyes and therefore these mouse models can be used as surrogates to understand drusen formation. In this PO1 component we will test the overarching hypothesis that dysregulation of the PPi/Pi ratio underlies the pathophysiology of ectopic calcification in diseases of aging, focusing our studies primarily on eye calcification. Given that tissue-nonspecific alkaline phosphatase (TNAP) is the major pyrophosphatase controlling the PPi/Pi ratio, TNAP may be a useful druggable target for the prevention/amelioration of drusen formation. Thus, the goals of this Project 4, designed to be mutually supportive with the other PO1 components, are to probe the causative role of PPi dysregulation in eye calcification by genetically manipulating the production and degradation of PPi in vivo. We will investigate if the PPi/Pi ratio is being controlled (either in the choroid endothelium, RPE cells or both compartments) via the production and function of a special type of extracellular vesicles known as matrix vesicles (MVs), where hydroxyapatite starts to form during physiological skeletal/dental mineralization, or if this ratio is controlled via the pathophysiological upregulation of TNAP activity alone. We will also conduct pharmacological proof-of-concept studies aimed at affecting calcification in the eye via modulating the production and degradation of systemic and local PPi concentrations. Completion of these studies, within the context of this multi-disciplinary team effort, will lead to novel insights into the interrelated pathophysiology of AMD, AD and vascular calcification and will validate a druggable pathway to address the unmet clinical need of treating/preventing ectopic calcification manifesting in these highly prevalent diseases of aging.

项目4摘要 焦磷酸失调的机理。骨骼和牙齿中的羟基磷灰石沉积是小心的 精心策划的生化过程旨在平衡无机焦磷酸盐（PPI）的浓度 潜在的钙化抑制剂和钙化启动子的局部浓度（PI）至 建立适当的PPI/PI比，以使受调节的组织矿化发生。虽然我们有一个很好的 了解哪些分子控制物理骨骼和牙齿矿化，存在有限的数据，因为 关于这些相同机制的改变是否导致眼睛，大脑和 衰老疾病的脉管系统，例如年龄相关的黄斑变性（AMD），阿尔茨海默氏病（AD） 和动脉粥样硬化。 AMD在临床上的特征是存在称为drusen的细胞外沉积物， 位于视网膜色素上皮（RPE）和该区域中的脉络膜微脉管系统之间 Bruch的膜位于黄斑区域。在与 局部炎症，黄斑区域中大量大drusen的存在是一个重大风险 开发AMD的因素。虽然没有完全反映人类病理生理学的鼠模型 AMD，ABCC6 - / - 和Pseudoxanthoma弹性瘤（PXE）的ENPP1 - / - 小鼠模型和广义 婴儿期（GACI）的动脉钙化，不仅表现出血管和脑钙化，而且表现 眼睛中的钙化，因此这些鼠标模型可以用作替代物来理解drusen 形成。在此PO1组件中，我们将测试PPI/PI比率失调的总体假设 基础是衰老疾病中依托钙化的病理生理学，主要集中于我们的研究 眼睛钙化。鉴于组织非特异性酒精磷酸酶（TNAP）是主要的焦磷酸酶 控制PPI/PI比，TNAP可能是预防/改善龙的有用的药物靶标 形成。这是该项目4的目标，旨在与其他PO1相互支持 组件是通过一般 操纵体内PPI的生产和降解。我们将调查PPI/PI比率是否为 通过生产和功能受控（在脉络膜内皮，RPE细胞或两个隔室） 一种特殊类型的细胞外蔬菜，称为基质蔬菜（MVS） 在物理骨骼/牙齿矿化期间，或者如果该比率通过病理生理控制 单独的TNAP活性上调。我们还将进行针对的药物证明研究 通过调节全身和局部PPI的产生和降解来影响眼睛的计算 浓度。在这项多学科团队的努力下，这些研究的完成将导致 对AMD，AD和血管钙化相互关联的病理生理学的新见解，并将验证 可吸毒的途径，以解决未满足的临床需要治疗/预防生态钙化表现的途径 这些高度普遍的衰老疾病。