The Role of Creb5 in Maintaining Synovial Joint Homeostasis

Creb5 在维持滑膜关节稳态中的作用

• 批准号: 10673141
• 负责人: Andrew Bruce Lassar
• 金额: $ 70.39万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-28 至 2027-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10673141
• 关键词: 3' Untranslated Regions; Address; Adult; Aging; Animals; Arthritis; Attenuated; Cattle; Cells; Chondrocytes; Competence; DNA Binding Domain; Degenerative polyarthritis; Development; Ectopic Expression; Embryo; Engineering; Enhancers; Environment; Epidermal Growth Factor Receptor; Epiphysial cartilage; Event; Exons; Failure; Fibroblasts; Friction; Genes; Genetic Recombination; Genetic Transcription; Goals; Hallmark Cell; Health; Homeostasis; Human; In Vitro; Injury; Joints; Knee; Knee joint; LoxP-flanked allele; Maintenance; Mechanics; Mediating; Meniscus structure of joint; Mus; Natural regeneration; Operative Surgical Procedures; Patients; Play; Proteins; Proteoglycan; Rattus; Rheumatoid Arthritis; Role; Sheep; Signal Pathway; Signal Transduction; Surface; Synovial Cell; Synovial Fluid; Synovial joint; Tissues; Transforming Growth Factor Beta 2; Transforming Growth Factor beta; Traumatic Arthropathy; Work; aged; articular cartilage; cartilage degradation; in vivo; inducible Cre; insight; joint injury; lubricin; mouse model; novel; postnatal; programs; protein expression; response; stem cell population; tissue regeneration; transcription factor

Project Summary/Abstract. The broad, long-term goal of this project is to develop a comprehensive understanding of the regulatory network that regulates the differentiation and maintenance of articular cartilage, which plays a central role in maintaining the low-friction environment of the joint space. Indeed, a hallmark of cells comprising the articular cartilage is their expression of proteoglycans, such as the protein lubricin, encoded by the Prg4 gene, that lubricates the joint and protects against the development of arthritis. Prg4 is specifically expressed in the superficial-most layer of the articular cartilage. Findings by both the Lassar lab and others have established that Prg4-expressing cells in the superficial zone of articular cartilage (in embryonic and early post-natal mice) serve as a stem cell population for all deeper regions of the articular cartilage in the adult. Furthermore, in both humans and mice lacking Prg4 (which encodes lubricin), the surface of the articular cartilage becomes damaged and precocious joint failure occurs. Notably, decreased levels of lubricin have been observed following surgically induced osteoarthritis in sheep, and in synovial fluid from patients with either osteoarthritis or rheumatoid arthritis. Furthermore, a decrease in lubricin expression during aging, correlates with increasing sensitivity of aged knees to cartilage degradation. Thus, a key objective of the Lassar lab has been to identify tissue-specific transcription factors that regulate the expression of both Prg4 and other genes that are specifically expressed in the superficial zone of the articular cartilage. Recent findings in the Lassar lab indicate that the transcription factor Creb5 is uniquely expressed in superficial zone articular chondrocytes (as opposed to both deeper zone articular chondrocytes and growth plate chondrocytes) and is a crucial regulator of Prg4 expression. Most notably, ectopic expression of Creb5 in deep zone bovine articular chondrocytes (which do not expression Prg4) enabled TGF-b2 and EGFR signals to induce Prg4 expression in these cells, to a level equal to that expressed by superficial zone articular chondrocytes. These findings suggest that Creb5 establishes a competent state in chondrocytes to express Prg4 in response to these signaling pathways. In addition, the Lassar lab has found that mice engineered to lack functional Creb5 fail to form many synovial joints. Taken together, these findings indicate that Creb5 plays a critical role in both the formation of synovial joints and is a both a novel and crucial regulator of Prg4/lubricin expression in articular chondrocytes. This project will determine the role of Creb5 in maintaining the health of all tissues in the mature synovial joint; will determine whether expression of Creb5 in either articular chondrocytes or synovial fibroblasts is attenuated during aging or during osteoarthritis; and finally will determine whether sustained expression of exogenous Creb5 in the synovial joint can boost lubricin expression and block degradation of this tissue either during aging or in a murine model for post-traumatic osteoarthritis.

项目摘要/摘要。 该项目的广泛、长期目标是全面了解监管网络 调节关节软骨的分化和维持，在维持关节软骨中发挥核心作用 关节空间的低摩擦环境。事实上，构成关节软骨的细胞的一个标志是 它们表达蛋白聚糖，例如由 Prg4 基因编码的润滑蛋白，可以润滑 关节并防止关节炎的发展。 Prg4具体表达在最表面的 关节软骨层。 Lassar 实验室和其他实验室的研究结果均证实 Prg4 表达 关节软骨表面区域的细胞（胚胎和产后早期小鼠）充当干细胞 成人关节软骨所有较深区域的人口。此外，在人类和小鼠中 缺乏 Prg4（编码润滑素），关节软骨表面会受损且早熟 发生关节故障。值得注意的是，在手术诱导后观察到润滑素水平下降 绵羊的骨关节炎，以及骨关节炎或类风湿性关节炎患者的滑液。 此外，衰老过程中润滑素表达的减少与老年膝盖的敏感性增加相关 导致软骨退化。因此，Lassar 实验室的一个关键目标是识别组织特异性转录 调节 Prg4 和其他在浅表中特异性表达的基因表达的因子 关节软骨的区域。 Lassar 实验室的最新发现表明转录因子 Creb5 是 在浅层关节软骨细胞中独特表达（与深层关节软骨细胞相反） 软骨细胞和生长板软骨细胞），是 Prg4 表达的重要调节因子。最值得注意的是，异位 Creb5 在深区牛关节软骨细胞（不表达 Prg4）中的表达启用 TGF-b2 EGFR 信号诱导这些细胞中 Prg4 的表达，达到与浅层区域表达的水平相同的水平 关节软骨细胞。这些发现表明 Creb5 在软骨细胞中建立了一种有能力的状态 表达 Prg4 来响应这些信号通路。此外，Lassar 实验室还发现小鼠经过基因改造 缺乏功能性的 Creb5 无法形成许多滑膜关节。总而言之，这些发现表明 Creb5 在滑膜关节的形成中起着至关重要的作用，并且是一种新颖且重要的调节剂 Prg4/lubricin 在关节软骨细胞中的表达。该项目将确定 Creb5 在维护 成熟滑膜关节中所有组织的健康；将确定 Creb5 是否在任一 关节软骨细胞或滑膜成纤维细胞在衰老或骨关节炎期间减弱；并最终将 确定滑膜关节中外源性 Creb5 的持续表达是否可以促进润滑素表达 并在衰老过程中或在创伤后骨关节炎的小鼠模型中阻止该组织的降解。