Studies of Osteoclast Lineage in Health and Disease

尽管我们对调节OC功能的分子信号了解很多，但我们对此知之甚少 OC从祖细胞发展而来的谱系发展和机制。此应用程序的目标是 是为了更好地定义OC前体(OCP)的开发和贩运以及规范这一过程的机制 在健康和疾病方面，以便我们可以确定潜在的药物靶点，以开发更好的骨骼疗法 疾病。中心假设是：1)在动态平衡期间，驻留骨髓的细胞是主要的OCP 来源，而在炎症或骨折修复期间，循环细胞成为 OCP。2)OCP向成骨细胞迁移、植入和成熟的调控机制不同 在健康和疾病状态之间。为了检验这些假设，我们提出了以下目标： 1.确定CX3CR1+OCP在动态平衡期间OC发育中的作用，并确定 调节它们归巢和植入的机制。 1)在不同日龄的CX3CR1-CreERT2-Ai14小鼠身上进行时程研究，以考察 标记为OC。我们还将监测标记的OCP在骨髓、血液和脾中的动力学。 1b)细胞受体EBI2和CX3CR1在OCP上表达，以前曾被认为与 影响OCP的归巢、植入和成熟。我们将确定它们在OCP谱系发展中的作用 并在体内利用CX3CR1-CreERT2-Ai14小鼠体内转运和基因缺失。 2.观察OCP在骨炎症和骨折修复过程中的循环归巢情况。 这些研究将检验两种疾病模型，在这两种模型中，我们以前证明了循环OCP是 被招募植入骨中：TNFa诱导的骨炎症和修复骨折。 2)研究肿瘤坏死因子α诱导的炎症性骨模型(WT Parabion将肿瘤坏死因子α注射到其头盖骨； 其他类似物是CX3CR1-EGFP；陷阱-td番茄小鼠)，并确定循环标记细胞的比率 炎症部位的家，形成OC，然后消失。OCP动力学将像在1A中一样进行测量。 2B)研究共生骨折模型(一个WT Parabion接受股骨骨折；另一个Parabion是 CX3CR1-EGFP；陷阱-td番茄小鼠)，并确定循环中的标记细胞回到 修复骨痂，形成OC，消失。OCP动力学将像在1A中一样进行测量。 2C)确定以TNFa诱导的炎症为主的循环OCP的表型和动力学 或通过注射来自CX3CR1-EGFP的不同群体的OCP；Trap-td番茄小鼠和 监测标记骨钙素在骨组织中的出现和消失情况。 2D)确定EBI2或CX3CR1 CXCR4的基因缺失是否改变了循环OCP到家和 在目标2C中研究的TNFa诱导的骨炎症和骨折修复模型中成熟为OC。

Although, we know much about the molecular signals that regulate OC function, we know relatively little about the lineage development and mechanisms that OC use to develop from progenitors. The goal of this application is to better define OC progenitor (OCP) development and trafficking and the mechanisms regulating this process in health and disease so that we can identify potential drug targets to develop superior therapies for bone diseases. The central hypotheses are: 1) During homeostasis marrow-resident cells are the principal OCP source, while during inflammation or fracture repair, circulating cells become a significant source of OCP. 2) The mechanisms regulating OCP migration, engraftment and maturation to OC in bone differ between healthy and disease states. To test these hypotheses, we propose the following aims: 1. Define the role that CX3CR1+ OCP have in OC development during homeostasis and identify mechanisms regulating their homing and engraftment. 1A) Perform time course studies in CX3CR1-CreERT2-Ai14 mice at various ages to examine the kinetics of labeled OC. We will also monitor the kinetics of labeled OCP in the bone marrow, blood and spleen. 1B) The cell receptors EBI2 and CX3CR1 are expressed on OCP and have previously been implicated to influence OCP homing, engraftment and maturation. We will determine their role in OCP lineage development and trafficking in vivo under homeostatic conditions using CX3CR1-CreERT2-Ai14 mice and gene deletion. 2. Examine OCP homing from the circulation during bone inflammation and fracture repair. These studies will examine two disease models in which we previously demonstrated that circulating OCP are recruited to engraft in bone: TNFa-induced bone inflammation and a repairing fracture. 2A) Study a TNFa-induced inflammatory bone model (a WT parabiont has TNFα injected over its calvaria; the other parabiont is a CX3CR1-EGFP; TRAP-tdTomato mouse) and determine the rate that circulating labeled cells home to the inflammatory site, form OC and disappear. OCP kinetics will be measured as in 1A. 2B) Study a parabiosis fracture model (a WT parabiont receives a femur fracture; the other parabiont is a CX3CR1-EGFP; TRAP-tdTomato mouse) and determine the rate that circulating labeled cells home to the repairing callus, form OC and disappear. OCP kinetics will be measured as in 1A. 2C) Determine the phenotype and kinetics of circulating OCP that home to bone with TNFa-induced inflammation or fracture repair by injecting various populations of OCP from CX3CR1-EGFP; TRAP-tdTomato mice and monitoring the rates that labeled OC appear and disappear in bone. 2D) Determine if gene deletion of EBI2 or CX3CR1 CXCR4 alters the ability of circulating OCP to home and mature into OC in the models of TNFa-induced bone inflammation and fracture repair studied in aim 2C.