Studies of Osteoclast Lineage in Health and Diseases

虽然我们对调节OC功能的分子信号了解很多，但对OC的分子信号却知之甚少。 OC用于从祖细胞发育的谱系和机制。该应用程序的目标是更好地 定义OC祖细胞（OCP）的成熟和运输以及调节健康过程的机制 这样我们就可以确定潜在的药物靶点，从而开发出针对骨骼疾病的上级疗法。的 中心假设是：1）在稳态期间，骨髓驻留细胞是主要的OCP来源， 而在炎症或骨折修复期间，循环细胞成为OCP的重要来源。 2)OCP在骨中迁移、植入和成熟为OC的调节机制不同 健康和疾病之间的关系。为了验证这些假设，我们提出了以下目标： 1.定义CX 3CR 1 + OCP在体内平衡过程中OC发育中的作用， 调节它们归巢、植入和成熟为OC的机制： 1A）在不同年龄的CX 3CR 1-CreERT 2-Ai 14小鼠中进行时程研究以检查标记的OC 形成动力学我们还将监测标记OCP在骨髓、血液和脾脏中的动力学。 1B）趋化因子受体CX 3CR 1在OCP上表达，并且先前已被暗示影响OCP。 OCP归巢、植入和成熟。我们将确定其在OCP谱系发展中的作用， 稳态条件下的体内运输（当骨髓来源的细胞作为OCP来源占主导地位时） 使用CX 3CR 1-CreERT 2-Ai 14小鼠产生Cx 3cr 1基因缺失。 2.检查骨炎症和骨折修复过程中OCP从循环中的归巢。 这些研究将检查两种疾病模型，在这两种模型中，我们先前证明了循环OCP是 招募来植入骨中：TNF α诱导的骨炎症和修复性骨折。 2A）研究TNF α诱导的炎性骨模型（WT副生物在其颅骨上注射TNFα; 另一种寄生虫是CX 3CR 1-EGFP; TRAP-tdTomato小鼠），并测定循环标记的比率， 细胞回到炎症部位，形成OC并消失。 2B）研究联体共生骨折模型（WT联体生物接受股骨骨折;另一个联体生物是股骨骨折;另一个联体生物接受股骨骨折。 CX 3CR 1-EGFP; TRAP-tdTomato小鼠），并测定循环标记细胞归巢至靶细胞的速率。 修复骨痂，形成OC并消失。 2C）确定循环OCP的表型和动力学，所述循环OCP在骨中归巢、成熟和植入， 通过注射来自CX 3CR 1-EGFP的选择的OCP群体，TNF α诱导的炎症或骨折修复; TRAP-tdTomato小鼠和监测标记的OC在骨中出现和消失的速率。 2D）确定Cx 3cr 1的缺失对循环OCP归巢、植入和转移的能力的影响。 在具有TNF α诱导的炎症的骨中成熟或使用联体共生和过继转移的骨折修复。

Although, we know much about the molecular signals that regulate OC function, we know relatively little about the lineage and mechanisms that OC use to develop from progenitors. The goal of this application is to better define OC progenitor (OCP) maturation 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, engraftment and maturation to OC: 1A) Perform time course studies in CX3CR1-CreERT2-Ai14 mice at various ages to examine labeled OC formation kinetics. We will also monitor the kinetics of labeled OCP in the bone marrow, blood and spleen. 1B) The chemokine receptor CX3CR1 is expressed on OCP and has previously been implicated to influence OCP homing, engraftment and maturation. We will determine its role in OCP lineage development and trafficking in vivo under homeostatic conditions (when marrow-derived cells predominate as the OCP source) using CX3CR1-CreERT2-Ai14 mice to generate Cx3cr1 gene deletions. 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. 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. 2C) Determine the phenotype and kinetics of circulating OCP that home, mature and engraft in bone with TNFa-induced inflammation or fracture repair by injecting selected populations of OCP from CX3CR1-EGFP; TRAP-tdTomato mice and monitoring the rates that labeled OC appear and disappear in bone. 2D) Determine the effect that deletion of Cx3cr1 has on the ability of circulating OCP to home, engraft and mature in bone with TNFa-induced inflammation or a fracture repair using parabiosis and adoptive transfer.