CCN proteins in cartilage formation and maintenance

CCN 蛋白在软骨形成和维护中的作用

• 批准号: 7460845
• 负责人: Karen M. Lyons
• 金额: $ 37.15万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-20 至 2010-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7460845
• 关键词: Accounting; Address; Adhesives; Adult; Affect; Alleles; Arthritis; Binding Sites; Cartilage; Cells; Chondrocytes; Chondrogenesis; Condition; Defect; Development; Disease; Dysplasia; Electron Microscopy; Employee Strikes; Epiphysial cartilage; Exhibits; Extracellular Matrix; Family; Family member; Fibroblasts; Gene Expression; Gene Expression Regulation; Genes; Human; Hypertrophy; In Vitro; Integrins; Joints; Knockout Mice; Ligands; Light; Maintenance; Mediating; Mediator of activation protein; Messenger RNA; Mus; Mutation; Normal tissue morphology; Osteogenesis; Output; Pathway interactions; Phenotype; Play; Process; Production; Proliferating; Protein Family; Proteins; Regulation; Regulatory Element; Role; Signal Pathway; Signal Transduction; Skeletal system; Tamoxifen; Testing; Tissues; Transcript; Transgenic Mice; Transgenic Organisms; Ursidae Family; articular cartilage; connective tissue growth factor; in vivo; laser capture microdissection; member; mutant; novel; promoter; protein distribution; recombinase; repaired; tumor progression

DESCRIPTION (provided by applicant): Members of the CCN family are key mediators of disease processes. CCN2/CTGF (Connective Tissue Growth Factor) is the major mediator of excess ECM synthesis in all fibrotic conditions studied to date, and CCN1/Cyr61 has potent proangiogenic activities in tumor progression. These proteins are proposed to act as matricellular proteins, coordinating signals mediated by ECM-integrin interactions with other pathways. However, which of the many in vitro activities of these proteins are physiologically relevant is unknown, because their functions in normal tissue development /maintenance are undefined. Studies of targeted mice demonstrate that CCN2/CTGF is essential for chondrogenesis. Whether CCN2 mediates its effects by acting as a ligand for integrins, affecting synthesis of ECM and its modulators, and/or altering the outputs of signaling pathways in cartilage will be investigated in aim one. The consequences of loss of Ccn2 on gene expression in discrete regions of the growth plate will be investigated to test the hypotheses that Ccn2 has global effects on ECM content, and to test whether output of specific signaling pathways is impacted by loss of CCN2. Signaling pathways controlling CCN2 expression in cartilage will be identified in aim two. As Ccn2-l- mice bear a striking resemblance to Sox9 mice, whether CCN2 is a direct target of Sox factors will be investigated. As one of the major phenotypes of Ccn2-/- mice is osteopenia as a result of defective chondrocyte hypertrophy, these studies will also shed light on signaling pathways essential for the ability of hypertrophic cartilage to control subsequent bone formation. A key question regarding the roles of matricellular proteins is the extent to which they fulfill overlapping functions. In vitro studies suggest broadly similar activities for CCNs. However, in no case has it been shown that CCN1 and CCN2 have overlapping functions. A unique role of CCN1 in chondrogenesis and in joint formation is revealed by analysis of Ccn1 null mice. In aim three this unique joint phenotype is investigated and a Ccn1 floxed allele is used to define the role of CCN1 in cartilage. Analysis of double and compound mutants will test directly the degree to which CCN1 and 2 fulfill overlapping functions. Finally, there is compelling evidence implicating multiple CCN family members as essential for the maintenance of adult articular cartilage. Ccn2 is one of the most abundant transcripts in adult articular cartilage, and articular chondrocytes respond to CCN2, leading to repair of articular defects. In humans, loss of a related gene, CCN6, leads to a progressive pseudorheumatoid dysplasia, a severe form of arthritis, suggesting that a major shared function for CCN proteins is to maintain articular cartilage. We test the hypothesis that CCN2 is vital for the maintenance of adult cartilage using a floxed Ccn2 allele and a tamoxifen-inducible Cre recombinase.

描述（由申请人提供）：CCN 家族成员是疾病过程的关键介质。 CCN2/CTGF（结缔组织生长因子）是迄今为止研究的所有纤维化病症中 ECM 过度合成的主要介质，CCN1/Cyr61 在肿瘤进展中具有有效的促血管生成活性。这些蛋白质被认为充当基质细胞蛋白质，协调 ECM 整合素与其他途径相互作用介导的信号。然而，这些蛋白质的许多体外活性中哪些与生理相关尚不清楚，因为它们在正常组织发育/维持中的功能尚不清楚。对靶向小鼠的研究表明，CCN2/CTGF 对于软骨形成至关重要。 CCN2是否通过作用介导其作用 作为整合素的配体，影响 ECM 及其调节剂的合成，和/或改变 目标一将研究软骨中的信号传导途径。我们将研究 Ccn2 缺失对生长板离散区域基因表达的影响，以检验 Ccn2 对 ECM 含量具有全局影响的假设，并测试特定信号通路的输出是否受到 CCN2 缺失的影响。目标二将确定控制软骨中 CCN2 表达的信号通路。由于 Ccn2-l- 小鼠与 Sox9 小鼠非常相似，因此将研究 CCN2 是否是 Sox 因子的直接目标。由于 Ccn2-/- 小鼠的主要表型之一是软骨细胞肥大缺陷导致的骨质减少，因此这些研究还将揭示肥大软骨控制后续骨形成能力所必需的信号通路。关于基质细胞蛋白的作用的一个关键问题是它们履行重叠功能的程度。体外研究表明 CCN 具有大致相似的活性。然而，在任何情况下都没有表明CCN1和CCN2具有重叠的功能。通过对 Ccn1 缺失小鼠的分析揭示了 CCN1 在软骨形成和关节形成中的独特作用。在目标三中，研究了这种独特的关节表型，并使用 Ccn1 floxed 等位基因来定义 CCN1 在软骨中的作用。双突变体和复合突变体的分析将直接测试 CCN1 和 2 实现重叠功能的程度。最后，有令人信服的证据表明多个 CCN 家族成员对于维持成人关节软骨至关重要。 Ccn2 是成人关节软骨中最丰富的转录物之一，关节软骨细胞对 CCN2 做出反应，导致关节缺损的修复。在人类中，相关基因 CCN6 的缺失会导致进行性假类风湿性发育不良（一种严重的关节炎），这表明 CCN 蛋白的主要共同功能是维持关节软骨。我们使用 floxed Ccn2 等位基因和他莫昔芬诱导型 Cre 重组酶检验了 CCN2 对于维持成人软骨至关重要的假设。