Peptidylarginine deiminase type 6 in rheumatoid arthritis pathogenesis

类风湿性关节炎发病机制中的 6 型肽基精氨酸脱亚胺酶

基本信息

批准号：
10317620
负责人：
Felipe Andrade
金额：
$ 39.63万
依托单位：
JOHNS HOPKINS UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-09-23 至 2024-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10317620
关键词：
Address Antigens Area Arginine Autoantibodies Binding Binding Sites Biochemical Biological Assay C-terminal Calcium Calcium Binding Catalysis Cells Cessation of life Citrulline Data Disease Disease Outcome Enzymes Event Family Germ Cells Goals Human Immune Immune Targeting Immune system Isoenzymes Joints Kinetics Lead Length Leukocytes Link Liver Lung Mediating Oocytes Pathogenesis Pathogenicity Pathologic Pathway interactions Patients Physiological Play Process Production Protein Isoforms Protein-arginine deiminase Proteins RNA Splicing Regulatory Pathway Research Rest Rheumatoid Arthritis Role Small Intestines Source Spleen Synovial Fluid Therapeutic Intervention Time Tissues Transcript Variant Work citrullinated protein human model in vitro activity in vivo insight interest member mutant neutrophil novel novel therapeutic intervention novel therapeutics peripheral blood response skeletal

项目摘要

PROJECT SUMMARY/ABSTRACT Citrullinated proteins are major targets of the immune system in rheumatoid arthritis (RA), with recent evidence suggesting that mechanisms that enhance citrullination are associated with the worst disease outcome. Protein citrullination is the enzymatic conversion of arginine residues to citrulline and is mediated by the family of calcium- dependent peptidylarginine deiminase (PAD) enzymes. Five PAD members have been found in humans, PAD1- 4, and the catalytically inactive PAD6. While several mechanisms have been linked to abnormal citrullination in RA, including hyperactivation of PADs (particularly PAD4) during neutrophil death and the production of autoantibodies that enhance PAD4 activity, regulatory pathways that control citrullination are poorly understood. Since PADs require supraphysiologic concentrations of calcium for activity in vitro, it is suspected that PAD activation in vivo requires additional factors that modulate the enzyme’s sensitivity for calcium. Such co-factors, however, have not been identified. Our preliminary data demonstrate that PAD6, which has no citrullinating activity, and 3 novel PAD6 splicing variants described for the first time in this proposal, act as co-factors that decrease the calcium requirement of PAD4 for catalysis. Moreover, we found that all PAD6 variants are abundant in neutrophils, which are considered a major source of citrullinated proteins in the RA joint. Taken together, we hypothesize that PAD6 and its variants may be responsible for modulating the magnitude of PAD4 activity both in physiologic and pathologic conditions. We will examine this hypothesis directly in the human model in three specific aims. In Aim 1, we will define how PAD6 variants regulate PAD4 activity with the goal of identifying the biochemical mechanisms by which PAD6 variants decrease the calcium requirement of PAD4. Aim 2 will define the expression and function of PAD6 and its splicing variants at the cellular level. Aim 3 will study the expression of PAD6 isoforms in RA synovial fluid to address their relationship with the abnormal production of citrullinated proteins in RA. Together, these studies will define novel interacting mechanisms of disease amplification relevant to sustain the production of citrullinated proteins in the RA joints. Furthermore, these studies may provide evidence for targeting PAD6 as a novel therapeutic strategy to modulate PAD4 activity, which is highly significant for diseases in which citrullination has been pathogenically implicated.

项目概要/摘要最近的证据表明，瓜氨酸蛋白是类风湿性关节炎 (RA) 免疫系统的主要靶标表明增强瓜氨酸化的机制与最糟糕的疾病结果相关。瓜氨酸化是精氨酸残基向瓜氨酸的酶促转化，由钙家族介导在人类中发现了五种依赖肽基精氨酸脱亚胺酶 (PAD) 酶：PAD1-。 4，以及催化失活的 PAD6，而多种机制与异常瓜氨酸化有关。 RA，包括中性粒细胞死亡期间 PAD（特别是 PAD4）的过度激活以及增强 PAD4 活性的自身抗体、控制瓜氨酸化的调节途径知之甚少。由于 PAD 需要超生理浓度的钙才能在体外发挥活性，因此怀疑 PAD 体内激活需要额外的因子来调节酶对钙的敏感性，然而，我们的初步数据尚未确定，PAD6 不具有瓜氨酸化作用。活性，以及本提案中首次描述的 3 个新颖的 PAD6 剪接变体，充当辅助因子减少 PAD4 催化的钙需求此外，我们发现所有 PAD6 变体都很丰富。中性粒细胞被认为是 RA 关节中瓜氨酸蛋白的主要来源。继续认为 PAD6 及其变体可能负责调节 PAD4 活性的大小我们将在三个人体模型中直接检验这一假设。在目标 1 中，我们将定义 PAD6 变体如何调节 PAD4 活性，以期确定 PAD6 变体如何调节 PAD4 活性。 PAD6 降低 PAD4 钙需求的生化机制将定义变体。 PAD6及其剪接变体在细胞水平的表达和功能目标3将研究表达。研究 RA 滑液中的 PAD6 亚型，以解决其与瓜氨酸异常产生的关系这些研究将共同定义与疾病放大相关的相互作用的新机制。维持 RA 关节中瓜氨酸蛋白的产生此外，这些研究可能提供。以 PAD6 为靶点作为调节 PAD4 活性的新型治疗策略的证据，这是非常重要的用于致病性涉及瓜氨酸化的疾病。