Mechanism of Tgfbr2 in chondroprotection

Tgfbr2的软骨保护机制

• 批准号: 8629692
• 负责人: Rosa A. Serra
• 金额: $ 31.24万
• 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/8629692
• 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致残的主要原因，但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导致了新的动物模型和新的概念，这与理解人类骨关节炎有关。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特定靶点。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。在此之前，我们培育了表达TGF- II型受体（Tgfbr2）在关节软骨中的显性阴性突变的转基因小鼠。对TGF-¿反应性的改变导致了一种类似于人类骨关节炎的进行性骨骼疾病。我们最近发现了TGF-¿的几个下游靶点，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 -磷酸腺苷5- prime -磷酸硫酸合成酶2 (Papss2)，与人类的脊椎骺端发育不良有关，并且是软骨中蛋白聚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-¿可以独立于mRNA的变化而提高软骨细胞中Sox9蛋白的水平。初步数据表明，用TGF-¿处理可导致Sox9的sumo化。Sumoylation已被证明可以调节蛋白质的稳定性、活性和细胞定位。我们假设TGF-¿维持