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 焦磷酸失调的机制。羟基磷灰石在骨骼和牙齿中的沉积是一个仔细的过程 精心策划的生化过程旨在平衡无机焦磷酸盐 (PPi) 的浓度，这是一种 有效的钙化抑制剂，以及钙化促进剂磷酸盐 (Pi) 的局部浓度， 建立适当的 PPi/Pi 比率以实现受调节的组织矿化。虽然我们有一个好的 了解哪些分子控制生理骨骼和牙齿矿化，存在有限的数据 这些相同机制的改变是否会导致眼睛、大脑和身体的异位钙化 衰老疾病中的血管系统，例如年龄相关性黄斑变性 (AMD)、阿尔茨海默病 (AD) 和动脉粥样硬化。 AMD 的临床特征是存在称为玻璃疣的细胞外沉积物， 位于视网膜色素上皮 (RPE) 和脉络膜微血管之间的区域，称为 黄斑区的布鲁赫膜。玻璃疣也可在与以下疾病相关的正常老化眼睛中观察到： 局部炎症，以及黄斑区存在大量大玻璃膜疣是一个重大风险 发展AMD的因素。虽然目前还没有完全反映人类病理生理学的小鼠模型 AMD、Abcc6-/- 和 Enpp1-/- 弹性假黄瘤 (PXE) 小鼠模型和广义 婴儿动脉钙化（GACI），不仅表现为血管和脑钙化，还表现为 眼睛钙化，因此这些小鼠模型可以用作了解玻璃疣的替代品 形成。在此 PO1 部分中，我们将测试总体假设，即 PPi/Pi 比率失调 是衰老疾病中异位钙化病理生理学的基础，我们的研究主要集中在 眼睛钙化。鉴于组织非特异性碱性磷酸酶 (TNAP) 是主要的焦磷酸酶 控制 PPi/Pi 比率，TNAP 可能是预防/改善玻璃疣的有用药物靶点 形成。因此，该项目 4 的目标旨在与其他 PO1 相互支持 成分，旨在通过遗传学手段探讨 PPi 失调在眼钙化中的致病作用 操纵体内 PPi 的产生和降解。我们将调查 PPi/Pi 比率是否为 通过生产和功能来控制（在脉络膜内皮、RPE细胞或两个室中） 一种特殊类型的细胞外囊泡，称为基质囊泡 (MV)，羟基磷灰石开始在其中形成 在生理骨骼/牙齿矿化过程中，或者如果通过病理生理学控制该比例 单独上调 TNAP 活性。我们还将进行药理学概念验证研究，旨在 通过调节全身和局部 PPi 的产生和降解来影响眼部钙化 浓度。在多学科团队努力的背景下完成这些研究将导致 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 药物途径来解决治疗/预防异位钙化的未满足的临床需求 这些非常普遍的衰老疾病。