Parathyroid hormone (PTH) modulates lipid metabolism in the skeletal niche

甲状旁腺激素 (PTH) 调节骨骼生态位中的脂质代谢

• 批准号: 10438842
• 负责人: Elizabeth Rendina-Ruedy
• 金额: $ 42.17万
• 依托单位: VANDERBILT UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-30 至 2025-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10438842
• 关键词: Adenosine Diphosphate; Adenosine Triphosphate; Adipocytes; Adipose tissue; Adult; Adverse event; Affect; Age; Anabolic Agents; Animal Model; Area; Bioenergetics; Bone Marrow; Buffers; Calcium; Caloric Restriction; Cells; Charge; Collagen Type I; Data; Dependence; Development; FDA approved; Fatty Acids; Financial Hardship; Forteo; Fracture; Genus Hippocampus; Goals; Health; High Pressure Liquid Chromatography; Hormone use; In Vitro; Laboratories; Late-Onset Disorder; Lead; Lipids; Lipolysis; Longevity; Measures; Metabolic; Metabolic Pathway; Metabolism; Mitochondria; Molecular; Monitor; Mus; Nonesterified Fatty Acids; Oleic Acids; Operative Surgical Procedures; Osteoblasts; Osteogenesis; Osteopenia; Osteoporosis; Outcome; Outcome Study; Ovariectomy; Oxidative Phosphorylation; PTH gene; Patients; Persons; Pharmaceutical Preparations; Phase; Population; Process; Production; Proteins; Public Health; Regulation; Respiration; Stromal Cells; Technology; Testing; Therapeutic; Up-Regulation; X-Ray Computed Tomography; adenosine monophosphate-adenosine; bone; bone health; bone mass; combat; comorbidity; design; experimental study; fatty acid oxidation; flexibility; hormonal signals; improved; in vivo; insight; lipid metabolism; liquid chromatography mass spectrometry; model design; mouse model; novel; osteoporosis with pathological fracture; oxidation; parathyroid hormone-related protein; primary outcome; response; side effect; skeletal; spine bone structure; tibia

PROJECT SUMMARY/ ABSTRACT The long-term goal of my laboratory is to develop a comprehensive understanding of how intracellular metabolic pathways impact bone health. Within this scope the current project aims to explore the osteo- anabolic effects of intermittent parathyroid hormone (iPTH) via its modulation of lipid metabolism on cells within the skeletal niche. Osteoporosis and osteopenia are late-onset diseases affecting a staggering 54 million people in the U.S . In addition to the financial burden, osteoporosis-related fractures often lead to multiple comorbidities which significantly reduce longevity. While anabolic agents that increase bone formation such as PTH or PTH related protein’s (PTHrP) have aided in the management of osteoporosis, patients still experience adverse side-effects. Therefore, continued development of refined therapeutic options is necessary. As such, this project presents dual, complimentary mechanisms whereby PTH signaling up-regulates lipolysis in bone marrow adipocytes (BMAdipo), releasing lipid species into the skeletal niche, while also enhancing fatty acid oxidation in osteoblasts. Given the intimate proximity of BMAdipo to osteoblasts, it stands to reason that PTH treatment acts on both BMAdipo to liberate lipid species while also ‘priming’ the osteoblast to utilize these lipids as a mechanism capable of supporting the energy demanding process of bone formation. Therefore, our overarching hypothesis is that PTH’s bone anabolic actions involve stimulation of lipolysis in BMAdipo and enhanced fatty acid oxidation in osteoblasts. We will test this hypothesis in two specific aims. The first aim (SA1) will determine the ability of PTH-stimulated BMAdipo lipolysis to support PTH-induced bone formation, both in vivo and in vitro. This will be accomplished using a new mouse model, developed by the Co-I, designed to specifically inhibit lipolysis in BMAdipo. These mice will then be ovariectomized (OVX) or sham-operated on and be treated with PTH or vehicle control. Skeletal and metabolic parameters will be assessed at the end of the study. In addition to this experiment, lipid species released from BMAdipo upon PTH treatment will be characterized using liquid chromatography-mass spectrometry (LC-MS). The second aim (SA2) will define PTH’s ability to alter osteoblast lipid metabolism via modulation of cellular bioenergetics. Tracing of 13C18 oleic acid will be performed using LC-MS to determine fatty acid metabolic fate during PTH treatment in osteoblasts. Additionally, osteoblast mitochondrial oxidative phosphorylation substrate dependency will be measured during PTH using Seahorse XFe96 technology. Finally, osteoblast bioenergetics will be monitored using reversed- phase high-performance liquid chromatography (RP-HPLC) to determine adenosine monophosphate (AMP), adenosine diphosphate (ADP), and ATP flux under control conditions and during PTH stimulation. In summary, the goal of this project is to enhance our understanding of PTH’s ability to promote bone formation via the modulation of lipid metabolism. This project is expected to have substantial health-related influence as it will identify new areas for therapeutic exploration that are crucial to improve the management of osteoporosis.

项目摘要/摘要 我的实验室的长期目标是全面了解细胞内 代谢途径影响骨骼健康。在这一范围内，目前的项目旨在探索骨科- 间歇性甲状旁腺激素(IPTH)调节细胞内脂代谢的合成代谢作用 骨灰龛。骨质疏松症和骨质疏松症是晚发性疾病，影响人数高达5400万 美国人 。 除了经济负担外，骨质疏松相关的骨折往往会导致多发性 显著降低寿命的合并症。而促进骨形成的合成代谢制剂，如 甲状旁腺激素或甲状旁腺激素相关蛋白(PTHrP)有助于治疗骨质疏松症，患者仍有经验 副作用。因此，继续开发改进的治疗方案是必要的。因此， 这个项目提出了两种互补的机制，即甲状旁腺素信号上调骨骼中的脂肪分解。 骨髓脂肪细胞(BMAdipo)，将脂肪释放到骨骼壁龛中，同时还增强脂肪酸 成骨细胞的氧化作用。鉴于BMAdipo与成骨细胞的密切关系，甲状旁腺素 治疗作用于BMAdipo和BMAdipo，以释放脂类物质，同时也使成骨细胞利用这些脂类。 作为一种能够支持骨形成所需能量过程的机制。因此，我们的 最重要的假设是甲状旁腺素的骨合成代谢作用包括刺激BMAdipo和BMAdipo的脂解 增强成骨细胞中的脂肪酸氧化。我们将在两个具体目标上检验这一假设。第一个目标 (SA1)将决定甲状旁腺素刺激的BMAdipo脂解支持甲状旁腺素诱导的骨形成的能力。 无论是在体内还是体外。这将通过使用由Co-I开发的、设计的新鼠标模型来实现 特异性地抑制BMAdipo中的脂解作用。然后这些小鼠将被摘除卵巢(OVX)或进行假手术 并接受PTH或车辆控制治疗。骨骼和代谢参数将在年末进行评估 这项研究。除了这项实验，BMAdipo在PTH治疗后释放的脂质物种将是 采用液-质联用(LC-MS)进行表征。第二个目标(SA2)将定义 甲状旁腺素通过调节细胞生物能量学改变成骨细胞脂代谢的能力。13C18油酸的示踪 在甲状旁腺激素治疗期间，将使用LC-MS进行酸化，以确定成骨细胞中脂肪酸代谢的命运。 此外，成骨细胞线粒体氧化磷酸化底物依赖性将在 采用海马XFe96技术的PTH。最后，成骨细胞生物能量学将使用反向- 反相高效液相色谱法测定一磷酸腺苷(AMP) 控制条件下和甲状旁腺激素刺激时的二磷酸腺苷(ADP)和三磷酸腺苷(ATP)通量。总而言之， 这个项目的目标是加深我们对甲状旁腺激素通过 调节脂类代谢。这一项目预计将产生重大的健康相关影响 确定新的治疗探索领域，这些领域对改善骨质疏松症的管理至关重要。