Epigenetic Regulation of Bone Regeneration in Inflammatory Disease

炎症性疾病中骨再生的表观遗传调控

基本信息

批准号：
9974476
负责人：
Jie Shen
金额：
$ 53.28万
依托单位：
WASHINGTON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-07-08 至 2024-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9974476
关键词：
Ablation Address Affect Binding Bone Regeneration Bone callus Cell Differentiation process Cells Chondrocytes Chronic Clinical Clinical Research Complex DNA Methylation DNA Modification Methylases DNMT3B gene Data Defect Diabetes Mellitus Disease Elderly Enzymes Epigenetic Process Event Fibroblasts Fracture Fracture Healing Genetic Genetic Transcription Goals Human Impaired healing Impairment In Vitro Inflammation Inflammation Mediators Inflammatory Inflammatory Response Knowledge Mediating Mesenchymal Stem Cells Methylation Molecular Mus Orthopedics Osteitis Osteoblasts Pathway interactions Patients Pharmacology Population Process Publications Rheumatoid Arthritis Role Series Signal Transduction Smoking Testing Therapeutic Intervention Time Transgenic Mice Trauma United States Up-Regulation Work bone quality cell type chronic inflammatory disease cytokine diabetic epigenetic regulation epigenome fracture risk gain of function healing in vivo inhibitor/antagonist loss of function new therapeutic target notch protein novel older patient osteoprogenitor cell progenitor promoter protective effect repaired response stem cell proliferation therapeutic candidate tool

项目摘要

ABSTRACT Inflamed bone fracture poses a significant clinical problem. In the United States, approximately 1.6 million bone fractures encounter prolonged healing or non-union each year, among which, the major population bearing with these clinical complications are patients with inflammatory conditions, e.g, elder patients, smoking, diabetic or rheumatoid arthritis (RA) patients. In these patients, the fracture risk is increased due to the poor bone quality, highlighting the potential deleterious role of chronic systemic inflammation in fracture repair. The overarching hypothesis of this proposal is that under inflammatory conditions, NF-κB, the principal mediator of inflammation, induces Rbpjκ expression through downregulating Dnmt3b and its DNA methylation activity. We further hypothesize that Dnmt3b GOF or Rbpjκ inhibition restores MPC differentiation and chondrocyte maturation that are reduced by inflammation during fracture repair. This hypothesis is supported by our preliminary data wherein we show that Dnmt3b is highly expressed in fracture callus during fracture repair and Dnmt3b is the major DNA methyltransferase (Dnmt) responsive to cytokine in MPCs and chondrocytes. Relevant to our proposal, we provide evidence that inflammatory signals inhibit Dnmt3b in MPCs and chondrocytes in an NF-κB-dependent manner. Consistently, mice with Dnmt3b loss-of-function (LOF) in MPCs and chondrocytes display delayed fracture repair; and Dnmt3b gain-of-function (GOF) in MPCs or chondrocytes shows protective effect from inflammation in vitro and accelerates fracture repair in mice. Mechanistically, MPC differentiation defect mediated by inflammation and Dnmt3b LOF coincide with upregulation of Rbpjκ in MPCs and Rbpjκ inhibition can restore differentiation capacity in vitro. In vitro mechanistic studies and in vivo LOF and GOF approaches will be used to modulate IKK2, Dnmt3b and Rbpjκ expression in MPCs and chondrocytes to dissect its effects during fracture repair process. Three main Specific Aims are proposed. Specific Aim 1 will delineate the effect of constitutively active NF-κB signaling (IKK2ca), as the principal molecular driver of inflammation, on Dnmt3b expression and fracture repair. Specific Aim 2 will establish the effect of Dnmt3b GOF in MPCs and chondrocytes on accelerating fracture repair. Specific Aim 3 will delineate the mechanism by which Dnmt3b regulates downstream target, Rbpjκ, during fracture repair. This work will enhance our understanding of mechanisms by which systemic inflammation (via the NF-κB pathway) affects the fracture healing process through Dnmt3b and identify downstream targets of Dnmt3b (such as Rbpjκ) as novel candidates for therapeutic intervention.

抽象的在美国，大约有 160 万人患有炎症性骨折。每年都会出现骨折长期愈合或不愈合的情况，其中，主要人群为患有这些临床并发症的是患有炎症的患者，例如老年患者、吸烟、糖尿病或类风湿性关节炎（RA）患者中，由于骨质量差，骨折风险增加。强调慢性全身炎症在骨折修复中的潜在有害作用。该提议的总体假设是，在炎症条件下，NF-κB（NF-κB）是主要的信号通路。炎症介质，通过下调 Dnmt3b 及其 DNA 甲基化诱导 Rbpjκ 表达我们进一步研究 Dnmt3b GOF 或 Rbpjκ 抑制可恢复 MPC 分化和活性。骨折修复过程中炎症会减少软骨细胞的成熟，这一假设得到了支持。因此，我们的初步数据表明，Dnmt3b 在骨折修复过程中在骨折愈伤组织中高度表达 Dnmt3b 是 MPC 和软骨细胞中对细胞因子有反应的主要 DNA 甲基转移酶 (Dnmt)。与我们的提议相关，我们提供了证据表明炎症信号抑制 MPC 中的 Dnmt3b，并且一致地，MPC 中 Dnmt3b 功能丧失 (LOF) 的小鼠以 NF-κB 依赖性方式表达软骨细胞。软骨细胞显示延迟的骨折修复；以及 MPC 或软骨细胞中的 Dnmt3b 功能获得（GOF） MPC 在体外显示出对炎症的保护作用并加速小鼠骨折修复。炎症和 Dnmt3b LOF 介导的分化缺陷与 MPC 中 Rbpjκ 的上调一致抑制Rbpjκ可恢复体外分化能力。体外机制研究和体内 LOF 和 GOF 方法将用于调节 IKK2、Dnmt3b 和 Rbpjκ 在 MPC 和软骨细胞中的表达，以剖析其在骨折修复过程中的三个主要作用。提出了具体目标 1 将描述组成型活性 NF-κB 信号传导的作用。 (IKK2ca) 作为炎症的主要分子驱动因素，影响 Dnmt3b 表达和骨折修复。目标 2 将确定 Dnmt3b GOF 在 MPC 和软骨细胞中加速骨折修复的作用。具体目标 3 将描述 Dnmt3b 在过程中调节下游靶标 Rbpjκ 的机制这项工作将增强我们对全身炎症机制的理解（通过 NF-κB 通路）通过 Dnmt3b 影响骨折愈合过程并确定骨折愈合的下游靶点 Dnmt3b（例如 Rbpjκ）作为治疗干预的新候选者。