The mechanisms of bone mass regulation by FIP200

FIP200调节骨量的机制

• 批准号: 8370347
• 负责人: Fei Liu
• 金额: $ 34.99万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8370347
• 关键词: Adult; Autophagocytosis; Biological; Blood; Bone Density; Bone Development; Bone Diseases; Calvaria; Cell Lineage; Cell physiology; Cells; Complex; Defect; Degradation Pathway; Development; Disease; Disease model; Embryo; Embryonic Development; Excision; Family; Future; Genes; Genetic; Glucocorticoids; Goals; Growth; Health; Homeostasis; Human; Interruption; Knock-out; Knockout Mice; Knowledge; Lesion; Malignant Neoplasms; Mammalian Cell; Measures; Membrane; Metabolic; Mitochondria; Molecular; Mus; Neonatal; Nutrient; Nutritional; Organelles; Osteoblasts; Osteoporosis; PTK2 gene; Pathogenesis; Pathway interactions; Patients; Perinatal; Phenotype; Play; Population; Proteins; Public Health; Reactive Oxygen Species; Regulation; Role; Signal Pathway; Signal Transduction; Signaling Molecule; Sirolimus; Skeletal Development; Staging; Starvation; Tissues; Transgenic Mice; Ubiquitin; Vascular blood supply; Woman; age group; aged; base; bone; bone cell; bone health; bone loss; bone mass; bone metabolism; cell type; improved; in vivo; inhibitor/antagonist; men; mouse model; mutant; novel; novel therapeutics; osteoblast differentiation; postnatal; prevent; research study; response; skeletal; treatment planning

DESCRIPTION (provided by applicant): The long term goal of the proposed studies is to understand the mechanisms of cell signaling in the regulation of key cellular functions in skeletal development/disease. In this proposal, we focus on the role of FIP200 (FAK-family Interacting Protein of 200 kDa) in the regulation of osteoblast differentiation. FIP200 was initially identifie as a novel FAK and Pyk2 inhibitor. Recently, FIP200 was identified as an essential component of mammalian autophagy. Despite our knowledge about FIP200 as a key signaling node in both embryogenesis and cancer development, it is unknown to what extent FIP200 regulates bone metabolism. In our preliminary studies, we found: 1. FIP200 conditional knockout in osteoblasts led to a severe osteopenic phenotype; 2. Osteoblast differentiation was greatly impaired in FIP200-null primary osteoblast cultures; 3. Primary calvarial osteoblasts have active basal and high inductive autophagy activity. However, FIP200 null primary calvarial osteoblasts expressing GFP-LC3 failed to form punctuate membrane structures in response to starvation and rapamycin treatment, indicating that FIP200 null osteoblasts had autophagy deficiency; 4. FIP200-null osteoblasts had large ubiquitin-positive aggregates, another indication of defective autophagy in these cells; and 5. Early neonatal FIP200 Osx-CKO mice had significant growth retardation in response to naturally occurring starvation as a result of sudden loss of maternal blood supply. Therefore, we hypothesize that FIP200 regulates bone mass through its regulation on osteoblast autophagy. The overall objective of the proposed project is to determine the molecular mechanisms and signaling pathways by which FIP200 regulates osteoblast function and bone mass using a combination of molecular, cell biological and mouse genetic approaches. The specific aims of this proposal are: Aim 1. To determine to what extent FIP200 regulates osteoblast function through its autophagic role. Aim 2. To elucidate the mechanism by which FIP200 regulates early postnatal bone development. Aim 3. To determine the role of FIP200 in bone homeostasis in adult mice. Health relevence: As a major public health threat, osteoporosis is present in an estimated 44 million men and women aged 50 and older, which represents 55 percent of the population in that age group in the USA. The proposed study with unique mouse disease model is highly valuable for determining the molecular and cellular mechanisms of pathogenesis of osteoporosis. It will allow us to define a novel bone mass regulation mechanism by autophagy, which is fundamentally important for the development of new therapeutics to treat bone diseases including osteoporosis. 1 PUBLIC HEALTH RELEVANCE: Osteoporosis is a condition in which the bones become weak and can break more easily. FIP200 is a newly identified signaling molecule that plays many important roles in different tissue/cell types. This proposed project will elucidate the mechanisms of osteoporotic lesion in a mouse model in which FIP200 is deficient. The pathways and mechanisms identified can be potentially utilized for the future novel treatment of osteoporosis as well as other bone diseases.

描述（由申请人提供）：拟议研究的长期目标是了解细胞信号传导在骨骼中关键细胞功能调节中的机制 发育/疾病。在本提案中，我们重点关注 FIP200（200 kDa 的 FAK 家族相互作用蛋白）在调节成骨细胞分化中的作用。 FIP200 最初被认为是一种新型 FAK 和 Pyk2 抑制剂。最近，FIP200 被确定为哺乳动物自噬的重要组成部分。尽管我们知道 FIP200 作为胚胎发生和癌症发展中的关键信号节点，但尚不清楚 FIP200 在多大程度上调节骨代谢。在我们的初步研究中，我们发现：1.成骨细胞中FIP200条件性敲除导致严重的骨质减少表型； 2. FIP200缺失的原代成骨细胞培养物中成骨细胞分化严重受损； 3.原代颅骨成骨细胞具有活跃的基础自噬活性和高诱导自噬活性。然而，表达GFP-LC3的FIP200无效的初级颅骨成骨细胞未能响应饥饿和雷帕霉素处理而形成点状膜结构，表明FIP200无效的成骨细胞具有自噬缺陷； 4. FIP200缺失的成骨细胞具有大量泛素阳性聚集体，这是这些细胞自噬缺陷的另一个迹象； 5.早期新生FIP200 Osx-CKO小鼠由于母体血液供应突然丧失而自然发生饥饿，因此出现显着的生长迟缓。因此，我们假设FIP200通过调节成骨细胞自噬来调节骨量。该项目的总体目标是结合分子、细胞生物学和小鼠遗传学方法，确定 FIP200 调节成骨细胞功能和骨量的分子机制和信号通路。该提案的具体目标是： 目标 1. 确定 FIP200 通过其自噬作用在多大程度上调节成骨细胞功能。目标 2. 阐明 FIP200 调节出生后早期骨发育的机制。目标 3. 确定 FIP200 在成年小鼠骨稳态中的作用。健康相关性：骨质疏松症是一项主要的公共卫生威胁，估计有 4400 万 50 岁及以上的男性和女性患有骨质疏松症，占美国该年龄段人口的 55%。所提出的利用独特的小鼠疾病模型的研究对于确定骨质疏松症发病机制的分子和细胞机制非常有价值。它将使我们能够通过自噬定义一种新的骨量调节机制，这对于开发治疗包括骨质疏松症在内的骨疾病的新疗法至关重要。 1 公众健康相关性：骨质疏松症是一种骨骼变得脆弱且更容易骨折的疾病。 FIP200 是一种新发现的信号分子，在不同的组织/细胞类型中发挥许多重要作用。该项目将阐明 FIP200 缺陷的小鼠模型中骨质疏松病变的机制。所确定的途径和机制可用于未来骨质疏松症以及其他骨疾病的新型治疗。