Mechanism of Tgfbr2 in chondroprotection

Tgfbr2的软骨保护机制

• 批准号: 8497046
• 负责人: Rosa A. Serra
• 金额: $ 31.18万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2018-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8497046
• 关键词: Adenoviruses; Affect; Animal Model; Arginine; Arthralgia; Arthritis; Binding Sites; Biochemical; Biological; Biomechanics; Bioreactors; Bovine Cartilage; Boxing; Cartilage; Cattle; Centers for Disease Control and Prevention (U.S.); Chondrocytes; Data; Degenerative polyarthritis; Deposition; Development; Dominant-Negative Mutation; Dysplasia; Engineering; Enzymes; Extracellular Matrix; Extracellular Matrix Proteins; Genes; Human; Inorganic Sulfates; Introns; Investigation; Joints; Knowledge; Laboratories; Lead; Lysine; Maintenance; Mediating; Messenger RNA; Modeling; Mus; Peptides; Phenotype; Plasmids; Prevention strategy; Process; Property; Proteins; Proteoglycan; RNA Interference; Regulation; Role; Signal Transduction; Site; Staining method; Stains; Stream; Testing; Tissue-Specific Gene Expression; Tissues; Transcriptional Activation; Transforming Growth Factor beta; Transgenic Mice; Unspecified or Sulfate Ion Sulfates; Virus; articular cartilage; cartilage regeneration; disability; expression vector; genetic manipulation; in vivo; joint function; mouse model; mutant; new therapeutic target; prevent; promoter; public health relevance; receptor; repaired; response; sex; skeletal disorder; sulfation; transcription factor; treatment strategy

DESCRIPTION (provided by applicant): Osteoarthritis is a leading cause of disability in the industrialized world but little is known about mechanisms of cartilage destruction associated with osteoarthritis. Recent advances in the genetic manipulation of mice have lead to new animal models and new concepts that are relevant to understanding osteoarthritis in humans. The long-term objective of my laboratory is to understand the factors that mediate the development, persistence, and repair of articular cartilage and to identify specific targets for prevention and treatment strategies for osteoarthritis. TGF-¿ is a multifunctional peptide that has been shown to regulate cellular differentiation and tissue-specific gene expression. Previously, we generated transgenic mice that express a dominant-negative mutation of the TGF-¿ type II receptor (Tgfbr2) in articular cartilage. Altered responsiveness to TGF-¿ resulted in a progressive skeletal disease that resembled osteoarthritis in humans. We recently identified several down-stream targets of TGF-¿ that regulate post-translational processing of the major extracellular matrix proteins in articular cartilage. One in particular, 3-Prime-Phoshoadenosine 5-Prime-Phosphosulfate Synthase 2 (Papss2), has been associated with Spondyloepimetaphyseal Dysplasias in humans and is required for proper sulfation of proteoglycans in cartilage. In addition to TGF-¿, the transcription factor Sox9 is also associated with the maintenance of mature articular cartilage. Our preliminary studies indicate that TGF-¿ enhances the level of Sox9 protein in chondrocytes independently of changes in mRNA. The preliminary data suggest that treatment with TGF-¿ results in sumoylation of Sox9. Sumoylation has been shown to regulate protein stability, activity and cellular localization. We hypothesize that TGF-¿ maintains the differentiated chondrocyte phenotype in permanent cartilages, like articular cartilage, by regulating Sox9 levels and activity via protein sumoylation. We propose to test this model with the following specific aims: 1a) to determine which sites on Sox9 are sumoylated in response to TGF-¿ and determine the role of sumoylation in TGF-¿-mediated Sox9 levels, localization, and activity; 1b) to determine the mechanism of TGF-¿-mediated sumoylation of Sox9; 2) to determine the mechanism of TGF-¿ mediated expression of Papss2 and 3) to determine if Papss2 activity can alleviate cartilage degeneration when TGF-¿ signaling is disrupted and determine if activation of TGF-¿'s chondroprotective signals can restore biochemical and biomechanical properties to OA cartilage. These studies will identify mechanisms of chondroprotection that can be used as targets for therapies in osteoarthritis.

描述（由申请人提供）：骨关节炎是工业化世界中导致残疾的主要原因，但人们对与骨关节炎相关的软骨破坏机制知之甚少。小鼠基因操作的最新进展催生了与了解人类骨关节炎相关的新动物模型和新概念。我实验室的长期目标是了解介导关节软骨发育、持续和修复的因素，并确定骨关节炎预防和治疗策略的具体目标。 TGF-¿ 是一种多功能肽，已被证明可以调节细胞分化和组织特异性基因表达。此前，我们培育了在关节软骨中表达 TGF-¿ II 型受体 (Tgfbr2) 显性失活突变的转基因小鼠。对 TGF-β 的反应性改变导致了一种类似于人类骨关节炎的进行性骨骼疾病。我们最近确定了 TGF-¿ 的几个下游靶标，它们调节关节软骨中主要细胞外基质蛋白的翻译后加工。特别是 3-Prime-Phoshoadenosine 5-Prime-Phosphosulfate Synthase 2 (Papss2)，它与人类的脊椎骨干骺端发育不良有关，并且是软骨中蛋白多糖适当硫酸化所必需的。除了 TGF-¿ 外，转录因子 Sox9 也与成熟关节软骨的维持有关。我们的初步研究表明，TGF-¿ 可以增强软骨细胞中 Sox9 蛋白的水平，而与 mRNA 的变化无关。初步数据表明，用 TGF-¿ 处理会导致 Sox9 的 SUMO 化。 Sumoylation 已被证明可以调节蛋白质稳定性、活性和细胞定位。我们假设 TGF-¿ 维持 通过蛋白质苏酰化调节 Sox9 水平和活性，形成永久软骨（如关节软骨）中分化的软骨细胞表型。我们建议以以下具体目标测试该模型：1a）确定 Sox9 上的哪些位点响应 TGF-¿ 被 sumoylated，并确定 sumoylation 在 TGF-¿ 介导的 Sox9 水平、定位和活性中的作用； 1b) 确定TGF-¿介导的Sox9苏酰化机制； 2) 确定 TGF-¿ 介导 Papss2 表达的机制，3) 确定当 TGF-¿ 信号被破坏时 Papss2 活性是否可以减轻软骨退化，并确定 TGF-¿ 软骨保护信号的激活是否可以恢复 OA 软骨的生化和生物力学特性。这些研究将确定软骨保护机制，可作为骨关节炎治疗的靶点。