Integrative genomics to define osteocyte differentiation, regulation and function

综合基因组学定义骨细胞分化、调节和功能

• 批准号: 8909062
• 负责人: J WESLEY PIKE
• 金额: $ 34万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-08 至 2019-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8909062
• 关键词: Affect; Binding; Biological; Bone Diseases; Bone Matrix; Bone Surface; Bone remodeling; Cardiovascular Physiology; Cardiovascular system; Cell Culture System; Cells; Cellular Mechanotransduction; ChIP-seq; Chromatin; Communication; Cues; DNA; DNA Binding; Data; Data Set; Disease; Endocrine; Enhancers; Epigenetic Process; Femur; Gene Expression; Gene Expression Profile; Gene Targeting; Genes; Genomics; Health; Histones; Homeostasis; Hormones; In Vitro; Individual; Kidney; Lead; Life; Location; Longevity; Maintenance; Marrow; Mediating; Medicine; Methods; Minerals; Modification; Molecular; Monitor; Morphology; Mus; Muscle; Nerve; Neurons; Osteoblasts; Osteocytes; Osteogenesis; Osteolysis; Osteoporosis; Pathologic; Pathway interactions; Pattern; Play; Process; Production; Property; RNA Sequences; Regulation; Relative (related person); Role; Route; Signal Pathway; Signal Transduction; Signal Transduction Pathway; Site; Skeleton; Therapeutic Intervention; Transact; Up-Regulation; Van Buchem disease; Work; base; bone; bone cell; cell type; epigenomics; genome-wide; in vivo; in vivo Model; inorganic phosphate; insight; mineralization; novel; paracrine; prevent; skeletal; skeletal disorder; substantia spongiosa; therapeutic target; transcription factor; transcriptome sequencing

DESCRIPTION (provided by applicant): Osteocytes are osteoblast-derived cells that are progressively entombed in mineralized matrix where they function to regulate skeletal homeostasis; their importance is highlighted both by their relative abundance and by their exceptionally long lifespan. Surprisingly, although osteocytes are known to manifest unique gene expression patterns relative to their osteoblast precursors and, as a consequence, display unique form and function, little is known of the molecular mechanisms that orchestrate their transition from the osteoblast or of the epigenomic and regulomic determinants that are responsible. In addition, although Wnt signaling is known to be a major but differential regulator of osteoblast and osteocyte activities, the majority of the gene targets that comprise the cell-specific activities of this pathway and the mechanisms through which TCF/LEF/b-catenin function to modulate these targets in both cell types remain unknown. Accordingly, the objectives of the first two aims are as follows. Aim 1: Identify the underlying epigenomic and regulomic mechanisms and associated molecular determinants that are responsible on a genome-wide scale for the osteoblast to osteocyte transition both in vitro and ex vivo. Aim 2: Examine and contrast the impact of the Wnt signaling pathway on osteoblast- and mature osteocyte-specific gene expression patterns and assess the molecular mechanisms through which these gene subsets are modulated directly by b-catenin and impacted by PTH and 1,25(OH)2D3 both in vitro and ex vivo. Our preliminary data and that of others have shown that a number of genes are upregulated during the osteocyte transition, including Sost, Fgf23, Tnfsf11, and Enpp1/3. The Sost gene, which encodes the Wnt pathway antagonist sclerostin (SCL), is of primary importance, however, due to its central biological actions on bone formation, its impact in disease, and its relevance as a potential therapeutic target. Progress has been made in understanding Sost regulation, prompted in part by the discovery that deletion of a downstream Sost enhancer alters Sost expression and is responsible for Van Buchem disease. Our preliminary data, however, suggest significant additional complexity, thus supporting the final objective of this proposal. Aim 3: Assess the molecular mechanisms that underlie both basal and regulated osteocyte expression of Sost at both epigenomic and regulomic levels in both in vitro and in vivo models. Osteocytes play unique roles in the skeleton and act in endocrine fashion to elaborate both local paracrine factors such as sclerostin and systemically active hormones such as FGF23. Pathologic consequences arising from aberrant osteocyte function can be catastrophic. Detailed basic insights arising from the proposed studies are likely to provide new routes of therapeutic intervention for a multiplicity of diseases that affect the skeleton.

描述（由申请人提供）：骨细胞是成骨细胞衍生的细胞，逐渐嵌入矿化基质中，发挥调节骨骼稳态的作用；它们的重要性因其相对丰富和异常长的寿命而凸显。令人惊讶的是，尽管已知骨细胞相对于其成骨细胞前体表现出独特的基因表达模式，并因此表现出独特的形式和功能，但人们对协调其从成骨细胞转变的分子机制或负责的表观基因组和调节组决定因素知之甚少。此外，虽然已知 Wnt 信号传导是成骨细胞和骨细胞活性的主要但有差异的调节因子，但构成该途径的细胞特异性活性的大多数基因靶标以及 TCF/LEF/b-catenin 在两种细胞类型中调节这些靶标的机制仍然未知。因此，前两个目标的目标如下。目标 1：确定在体外和离体全基因组范围内负责成骨细胞向骨细胞转变的潜在表观基因组和调节组机制以及相关分子决定因素。目标 2：检查并对比 Wnt 信号通路对成骨细胞和成熟骨细胞特异性基因表达模式的影响，并评估这些基因子集在体外和离体过程中直接受 β-连环蛋白调节以及受 PTH 和 1,25(OH)2D3 影响的分子机制。我们和其他人的初步数据表明，许多基因在骨细胞转变过程中上调，包括 Sost、Fgf23、Tnfsf11 和 Enpp1/3。然而，编码 Wnt 通路拮抗剂硬化素 (SCL) 的 Sost 基因至关重要，因为它对骨形成具有重要的生物学作用、对疾病的影响以及作为潜在治疗靶点的相关性。在理解 Sost 调控方面取得了进展，部分原因是发现下游 Sost 增强子的缺失会改变 Sost 表达并导致 Van Buchem 病。然而，我们的初步数据表明存在显着的额外复杂性，从而支持了该提案的最终目标。目标 3：在体外和体内模型的表观基因组和调节组水平上评估 Sost 基础骨细胞表达和调节骨细胞表达的分子机制。骨细胞在骨骼中发挥着独特的作用，并以内分泌方式发挥作用，以产生局部旁分泌因子（如硬化素）和全身活性激素（如 FGF23）。骨细胞功能异常引起的病理后果可能是灾难性的。拟议研究产生的详细基本见解可能为多种疾病的治疗干预提供新途径 影响骨骼。