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家族的成员是疾病过程的关键介体。在迄今为止研究的所有纤维化条件下，CCN2/CTGF（结缔组织生长因子）是过量ECM合成的主要介体，并且CCN1/CYR61在肿瘤进展中具有有效的促血管生成活性。这些蛋白被提出充当母细胞蛋白，协调通过ECM-整合素与其他途径相互作用介导的信号。但是，这些蛋白质的许多体外活性在生理上是相关的，因为它们在正常组织发育 /维持中的功能不确定。对靶向小鼠的研究表明，CCN2/CTGF对于软骨生成至关重要。 CCN2是否通过行动介导了其效果 作为整联蛋白的配体，影响ECM及其调节剂的合成和/或改变的输出 软骨中的信号通路将在AIM ONE中进行研究。将研究CCN2损失CCN2对生长板离散区域中基因表达的后果，以测试CCN2对ECM含量具有全球影响的假设，并测试特定信号通路的输出是否受到CCN2损失的影响。在AIM 2中将确定控制软骨中CCN2表达的信号通路。由于CCN2-L-小鼠与Sox9小鼠具有惊人的相似之处，因此CCN2是否是Sox因子的直接靶标。作为CCN2 - / - 小鼠的主要表型之一，由于软骨细胞肥大缺陷，这些研究还将揭示出对控制肥厚性软骨控制后续骨形成所必需的信号通路。关于母细胞蛋白的作用的一个关键问题是它们实现重叠功能的程度。体外研究表明，CCN的活动广泛相似。但是，在任何情况下都没有证明CCN1和CCN2具有重叠的功能。 CCN1在软骨生成和关节形成中的独特作用是通过对CCN1 NULL小鼠的分析揭示的。在AIM三中，研究了这种独特的联合表型，并使用CCN1 FloxErele来定义CCN1在软骨中的作用。对双重和复合突变体的分析将直接测试CCN1和2实现重叠函数的程度。最后，有令人信服的证据暗示多个CCN家庭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本之一，关节软骨细胞对CCN2有反应，从而修复了关节缺陷。在人类中，相关基因CCN6的丧失导致进行性伪干性发育不良，这是一种严重的关节炎形式，这表明CCN蛋白的主要共享功能是维持关节软骨。我们检验了CCN2对于使用Floxed CCN2等位基因和他莫昔芬诱导的CRE重组酶维持成人软骨至关重要的假设。