Role of Osteoactivin in Osteoclasts

骨激活素在破骨细胞中的作用

• 批准号: 7591159
• 负责人: Matilda Han-Chin Sheng
• 金额: $ 0.07万
• 依托单位: LOMA LINDA VETERANS ASSN RESEARCH & EDUC
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-01 至 2009-10-24
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7591159
• 关键词: Address; Bone Resorption; Cell Adhesion; Cell Nucleus; Cells; Development; Disease; Endothelial Cells; Functional disorder; Genes; Growth; In Vitro; Integrins; Measures; Mediating; Molecular; Mus; Mutate; Osteoblasts; Osteoclasts; Osteoporosis; Pathway interactions; Pharmaceutical Preparations; Physiology; Play; RGD (sequence); Regulation; Role; Signal Transduction; Small Interfering RNA; Testing; Tissues; Transgenic Mice; Variant; Wasting Syndrome; Work; bone; effective therapy; in vivo; insight; migration; mutant; novel; osteoactivin; osteoblast differentiation; overexpression; promoter; repaired; tartrate-resistant acid phosphatase

DESCRIPTION (provided by applicant): Bone resorption is essential for all aspects of bone physiology: growth, remodeling, and repair. The most prevalent disease associated with an abnormality in bone resorption is osteoporosis, which is frequently a result of an excess bone resorption. The osteoclast is the primary bone-resorbing cells. Understanding the molecular mechanisms that regulate osteoclast formation and activity could provide insights into the pathophysiology of osteoporosis, and also better use of the currently available anti-resorptive drugs for bone wasting diseases. This project seeks to define the functional role of a new osteoclastic gene, osteoactivin (OA), in osteoclast formation and function and its potential molecular mechanism. OA is expressed in a wide variety of tissues and has been suggested to play a regulatory role in osteoblast differentiation and in endothelial cell adhesion. This proposal presented evidence that 1) OA is highly expressed in mature osteoclasts and its expression is upregulated during the differentiation of osteoclasts, 2) OA has a regulatory role in osteoclast formation, spreading, and activity, and 3) its molecular mechanism involves an interaction with integrin ¿3 and/or ¿1, presumably through its RGD motifs. Accordingly, this revised proposal tests two specific hypotheses: 1) OA has an important regulatory role in osteoclast formation and bone resorption activity in vivo and in vitro; and 2) OA regulates osteoclast formation and/or bone resorption activity in an integrin-dependent manner through its RGD motifs. The first hypothesis is addressed by two approaches: In the in vitro approach, primary murine osteoclast precursors will be used to determine if siRNA-mediated OA gene knockdown interferes with the RANKL-induced differentiation of osteoclasts as measured by osteoclast size, number of nuclei per osteoclast, migration, and bone resorption. The second in vivo approach is to generate transgenic mice with targeted overexpression of OA in cells of osteoclast lineage using the tartrate-resistant acid phosphatase C promoter. The in vivo function of OA on osteoclast formation and resorption will be determined by assessing the effects of targeted overexpression of OA on osteoclast formation and functions in the transgenic mice in vivo. The second hypothesis is tested by two strategies: the first strategy is to, with the use of preosteoclasts of OA transgenic mice, determine if siRNA-mediated knockdown of integrin ¿3 and/or ¿1 expression blocks the OA-induced increase in osteoclast formation and/or functions. The second strategy is to determine the effects of forced overexpression of RGD-mutated OA variants in murine osteoclast precursors on osteoclast formation, migration, and resorption, and compare the effects of forced overexpression of RGD- mutants in osteoblasts on osteoblast differentiation. If the hypotheses are correct, this work will provide insights into the functional role of this novel osteoclastic gene and define the interaction between OA and the integrin signaling in the regulation of osteoclast formation and activity. It may also provide a novel gene or pathway target for development of novel and effective treatment of osteoporosis and related bone-wasting diseases.

描述（由申请人提供）：骨吸收对于骨生理学的各个方面都是至关重要的：生长、重塑和修复与骨吸收异常相关的最常见的疾病是骨质疏松症，这通常是骨吸收过度的结果。破骨细胞是主要的骨吸收细胞，了解调节破骨细胞形成和活性的分子机制可以深入了解骨质疏松症的病理生理学，并更好地利用现有的现有技术。该项目旨在确定一种新的破骨细胞基因——骨激活素（OA）在破骨细胞形成和功能中的功能作用及其在多种组织中表达的潜在分子机制。已被认为在成骨细胞分化和内皮细胞粘附中发挥调节作用，该提议提供的证据表明：1) OA 在成熟破骨细胞中高表达，并且其表达在成骨细胞分化过程中上调。破骨细胞，2) OA 在破骨细胞形成、扩散和活性中具有调节作用，3) 其分子机制涉及与整合素的相互作用 ¿ 3 和/或 ¿ 1，大概通过其 RGD 基序，该修订后的提案测试了两个具体假设：1）OA 在体内和体外的破骨细胞形成和骨吸收活性中具有重要的调节作用；2）OA 调节破骨细胞形成和/或骨。通过其 RGD 基序以整合素依赖性方式进行吸收活性 第一个假设通过两种方法解决：在体外方法中，将使用原代小鼠破骨细胞前体来确定 siRNA 是否介导。 OA 基因敲低干扰 RANKL 诱导的破骨细胞分化（通过破骨细胞大小、每个破骨细胞的细胞核数量、迁移和骨吸收来测量）第二种体内方法是产生在破骨细胞谱系细胞中定向过度表达 OA 的转基因小鼠。使用抗酒石酸酸性磷酸酶 C 启动子，通过评估 OA 的靶向过度表达对破骨细胞形成和吸收的影响来确定 OA 对破骨细胞形成和吸收的体内功能。转基因小鼠体内破骨细胞的形成和功能通过两种策略进行测试：第一种策略是利用 OA 转基因小鼠的前破骨细胞，确定 siRNA 介导的整合素敲低是否有效。 3 和/或 ¿第二种策略是确定小鼠破骨细胞前体中 RGD 突变的 OA 变体的强制过度表达对破骨细胞形成、迁移和吸收的影响，并比较这些影响。如果假设正确，这项工作将深入了解这种新型破骨细胞基因的功能作用，并定义 OA 与成骨细胞之间的相互作用。整合素信号在破骨细胞形成和活性的调节中也可能为开发新的、有效的骨质疏松症和相关骨消耗疾病的治疗提供新的基因或途径靶点。