Mechanistic basis of the role of Cbx3 in negatively regulating osteoclast differentiation through epigenetic modification

这项研究的长期目标是开发更安全和有效的治疗方法，治疗由骨质疏松症引起的骨丢失 破骨细胞(OC)过度分化与许多代谢性骨病有关。眼前的目标是 这个应用程序是为了了解OC分化是如何通过由 转录因子和表观遗传调节因子可能成为骨病治疗的新靶点 比如骨质疏松症。由于缺乏对溶骨性疾病的认识，目前的治疗方法受到阻碍。 负性调节OC功能以防止骨丢失的机制。此外， 转录因子和表观遗传因子共同调控的机制(S)，特别是负调控 共同调节、OC分化和功能尚不清楚。我们已经鉴定出Cbx3/Hp1γ。我们的后续行动 免疫沉淀分析证实C/EBPα与Cbx3/Hp1γ相互作用。值得注意的是，我们的初步调查 数据显示Cbx3/Hp1γ过表达抑制OC的分化和活性，而Cbx3/Hp1γ沉默 增强OC血统承诺和形成。一贯地，Cbx3/Hp1γ缺陷小鼠被发现表现出 骨质疏松症样表型，由于OC的形成和活性增强。有趣的是，通过芯片分析，我们 发现Cbx3/Hp1γ在C/EBPα调控的OC基因的启动子上有几个结合位点 C-fos。我们的rna-seq分析还表明，单核细胞中cbx3缺乏导致oc基因增加。 表情。综上所述，初步数据表明，Cbx3可以抑制C/EBPα介导的OC 分化和活性。根据我们的初步研究，我们假设Cbx3对 表观遗传与C/eBPα及表观遗传因子相互作用诱导破骨细胞分化 骨稳态中破骨细胞基因表达的调控与预防。我们将检验这一假设 通过三个具体目标。在目标1中，我们研究了Cbx3在OC分化、骨骼组织中的功能 生理和病理条件下的发育和骨稳态 通过功能丧失研究两种Cbx3 CKO小鼠模型的表型和发病机制。在AIM 2、我们确定了Cbx3在成骨细胞分化、骨骼发育和骨稳态中的作用。 Cbx3的表型和致病机制的生理病理条件 通过功能获得法获得条件转基因过表达小鼠。我们定义了分子 Cbx3通过与C/EBPα和Cbx3相互作用负性调节OC分化的机制 控制AIM中的表观遗传修饰3.本研究将阐明Cbx3通过 与转录因子和其他表观遗传因子协同负向调节OC分化和 活动。从这项研究中获得的见解不仅将解决关于表观遗传学的基本科学问题 在OC生物学中对基因表达的调控，也将为最终目标提供基础 促进设计更安全和新颖的治疗溶骨性疾病(如骨质疏松症)的方法。

The long term goal of this study is to develop safer and effective therapeutic approach for bone loss caused by excessive osteoclast (OC) differentiation implicated in many metabolic bone diseases. The immediate goal of this application is to understand how OC differentiation is regulated through negative signaling mediated by transcription factors and epigenetic regulators, which may serve as novel therapeutic targets for bone diseases such as osteoporosis. Current therapies for osteolytic diseases are hindered by lack of understanding of the mechanisms underlying the negative regulation of OC function to prevent bone loss. Moreover, the mechanism(s) underlying how transcriptional factors and epigenetic factors co-regulate, especially negatively co-regulate, OC differentiation and function remain unclear. We have identified Cbx3/HP1γ. Our subsequent immunoprecipitation analysis confirmed that C/EBPα interacts with Cbx3/HP1γ in OCs. Notably, our preliminary data showed that Cbx3/HP1γ overexpression inhibited OC differentiation and activity, while Cbx3/HP1γ silencing enhanced OC lineage commitment and formation. Consistently, Cbx3/HP1γ-deficient mice were found to exhibit osteoporosis-like phenotype due to enhanced OC formation and activity. Interestingly, through ChIP analysis, we found several binding sites of Cbx3/HP1γ on the promoters of C/EBPα regulated OC genes, NFATC1 and C-FOS. Our RNA-seq analysis also revealed that Cbx3 deficiency in monocytes led to increased OC gene expression. Collectively, the preliminary data indicated that Cbx3 can restrict C/EBPα-mediated OC differentiation and activity. Based on our preliminary studies, we hypothesize that Cbx3 negatively regulates osteoclast differentiation through interacting with C/EBPα and epigenetic factors as a result of epigenetic modification and preventing osteoclast gene expression in bone homeostasis. We will test the hypothesis through three specific aims. In Aim 1, we examine the function of Cbx3 in OC differentiation, skeletal development and bone homeostasis under physiological and pathological conditions through characterization of the phenotypes and pathomechanism in two Cbx3 CKO mouse models through loss-of-function studies. In Aim 2, we determine the role of Cbx3 in OC differentiation, skeletal development and bone homeostasis under physiological and pathological conditions by characterizing the phenotypes and pathomechanism in Cbx3 conditional transgenic overexpression mice through gain-of-function approach. We define the molecular mechanism underlying how Cbx3 negatively regulates OC differentiation through interacting with C/EBPα and controlling epigenetic modification in Aim 3. The study will elucidate the mechanism(s) through which Cbx3 cooperates with transcriptional factors and other epigenetic factors to negatively regulate OC differentiation and activity. Insights gained from this study will not only address the basic scientific question about epigenetic regulation of gene expression in OC biology, but also will provide the foundation for the ultimate goal of facilitating the design of safer and novel therapeutic approach for osteolytic diseases (e.g. osteoporosis).