Regulatory mechanisms in osteoclasts

破骨细胞的调节机制

• 批准号: 7578433
• 负责人: YONGWON CHOI
• 金额: $ 36.56万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-24 至 2014-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7578433
• 关键词: ATP phosphohydrolase; Affect; Albers-Schonberg disease; Amino Acids; Bone Diseases; Bone Marrow; Bone Resorption; Cell Lineage; Cell fusion; Cells; Complementary DNA; Coupled; Data; Defect; Dendritic Cells; Development; Disease; Equilibrium; Exhibits; Extracellular Matrix; Generations; Goals; Hematopoiesis; Homeostasis; Homologous Gene; Knockout Mice; Knowledge; Lead; Length; Mediating; Minerals; Molecular; Molecular Profiling; Myelogenous; Osteoblasts; Osteoclasts; Osteogenesis; Osteoporosis prevention; Pathway interactions; Protein Isoforms; Proteins; Proton Pump; Regulation; Reporting; Role; Signal Transduction; Site; Staging; Testing; Therapeutic; bone; bone mass; bone metabolism; bone turnover; improved; in vivo; insight; mRNA Expression; macrophage; mineralization; monocyte; mouse model; novel; precursor cell; public health relevance; research study; stem; treatment strategy; vacuolar H+-ATPase

DESCRIPTION (provided by applicant): Bones provide rigid support for the body, maintain mineral homeostasis, and serve as the primary site for hematopoiesis. Bone homeostasis is maintained through the balanced and coupled actions of osteoblasts and osteoclasts. Bone-resorbing osteoclasts are derived from myeloid-lineage precursor cells, which also yield immunocytes such as macrophages and dendritic cells. This application stems in part from our attempt to understand how osteoclasts differ functionally and developmentally from immunocytes. In our preliminary data, we describe a novel subunit isoform of v-ATPase of previously unknown function, Atp6v0d2, expression of which is highly enriched in osteoclasts. We show that Atp6v0d2 knockout mice exhibit mild osteopetrosis due to decreased bone resorption. To our surprise, however, Atp6v0d2 does not appear to be involved in the v-ATPase proton pump, which is required for osteoclast-mediated bone resorption. Rather, Atp6v0d2 is critical for the optimal generation of multinucleated osteoclasts. In addition, Atp6v0d2 knockout mice exhibit increased bone formation, even though Atp6v0d2 expression was not detected in osteoblasts. Moreover, when tested directly ex vivo, Atp6v0d2-deficient osteoblasts do not show any intrinsic defects in their differentiation or mineralization of extracellular matrix. These observations strongly suggest that Atp6v0d2 knockout mice show enhanced bone formation as a result of unknown osteoblast-extrinsic mechanisms, possibly via Atp6v0d2-deficient osteoclast lineage cells. Finally, by examining Atp6v0d2 expression, we show that NFATc1 may regulate cell-cell fusion between preosteoclasts, in part, by regulating the induction of Atp6v0d2 expression, suggesting that signaling cascades that regulate the differentiation of preosteoclasts from myeloid precursors may be active during multiple stages of osteoclast development. Therefore, we propose to extend these studies of the regulation of bone homeostasis and osteoclast maturation by pursuing the following specific aims: (1) determining the extent to which Atp6v0d2 deletion affects bone metabolism in vivo, (2) determining whether osteoclast lineage cells per se can increase bone formation in vivo, and (3) extending our understanding of osteoclast maturation by studying signaling cascades that regulate Atp6v0d2 expression and the multinucleation of preosteoclasts. The knowledge gained from these studies will provide insights into how different molecules cooperate to induce osteoclast differentiation, and how osteoclasts and osteoblasts communicate to cross-regulate their functions, which may lead to novel or improved therapeutic strategies for the treatment and prevention of osteoporosis and other bone diseases. PUBLIC HEALTH RELEVANCE: Osteoclasts are the principal, if not the only, cells that can resorb bone. Thus, understanding the molecular pathways leading to the differentiation and activation of osteoclasts will help improve the treatment and prevention of osteoporosis as well as other diseases involving bone destruction.

描述（由申请人提供）：骨骼为人体提供严格的支撑，维持矿物质稳态，并作为造血的主要部位。通过骨细胞和破骨细胞的平衡和耦合作用来维持骨稳态。骨呈现的破骨细胞源自髓样细胞前体细胞，该细胞还产生巨噬细胞和树突状细胞等免疫细胞。该应用部分源于我们试图了解破骨细胞与免疫细胞的功能和发育之间的差异。在我们的初步数据中，我们描述了先前未知功能的V-ATPase的新型亚基同工型ATP6V0D2，其表达高度富集在破骨细胞中。我们表明，由于骨吸收降低，ATP6V0D2敲除小鼠表现出轻度的骨质倍率。然而，令我们惊讶的是，ATP6V0D2似乎没有参与V-ATPase质子泵，这是破骨细胞介导的骨吸收所必需的。相反，ATP6V0D2对于最佳生成多核破骨细胞至关重要。此外，即使在成骨细胞中未检测到ATP6V0D2表达，ATP6V0D2敲除小鼠的骨形成增加。此外，当直接进行离体测试时，ATP6V0D2缺陷成骨细胞在其分化或细胞外基质的分化或矿化时不会显示任何内在缺陷。这些观察结果强烈表明，由于未知的成骨细胞 - 超额机制，ATP6V0D2基因敲除小鼠可能通过ATP6V0D2缺陷骨细胞细胞而显示出增强的骨形成。最后，通过检查ATP6V0D2的表达，我们表明NFATC1可以通过调节ATP6V0D2表达的诱导来调节细胞细胞融合，这表明调节在多阶段的soste oste osteepages ostepages ostepages ostepages septage oste osteclast septepains conscade cascade cascade cascade cascade。因此，我们建议通过追求以下特定目的来扩展这些研究骨稳态和破骨细胞成熟的调节的研究：（1）确定ATP6V0D2缺失在体内影响骨代谢的程度，（2）确定每次See的骨骼在Vivo中的骨骼和3）是否会增加骨骼的骨骼形式，并且（3）在vivo中增加了ost（3）MIM（3）MIM（3）MIM（3）MIM（3）MIM（3）MIM（3）MIM（3）MIM（3）MIM（3）MIM（3）MIM（2）信号传导级联反应ATP6V0D2表达和pe骨前的多核。从这些研究中获得的知识将提供有关不同分子如何合作诱导破骨细胞分化的见解，以及破骨细胞和成骨细胞如何交流以交叉调节其功能，这可能会导致新颖或改进的治疗策略，以治疗和预防骨质骨骼和其他骨骼疾病。 公共卫生相关性：破骨细胞是可以吸收骨骼的细胞的主要细胞。因此，了解导致破骨细胞分化和激活的分子途径将有助于改善骨质疏松症的治疗和预防以及其他涉及骨骼破坏的疾病。