TRANSGLUTAMINASE PROMOTES CPPD DISEASE IN AGING JOINTS

描述（改编自申请人的摘要）：焦磷酸钙 二水合物（CPPD）沉积病是一种常见的退行性疾病， 关节炎，优先影响老年人。 CPPD的原因 在老化的关节软骨中的晶体形成是未知的，尽管许多 正常软骨矿化过程之间存在相似性， 生长板和病理性矿化引起的CPPD疾病。 目前的证据表明，CPPD晶体的形成是由于过量的 软骨细胞对无机焦磷酸盐（PPi）的加工， 或在关节软骨囊泡（ACV）周围和在改变的 软骨基质 已知促进CPPD晶体形成的方法是 转化生长因子β的强烈和独特的增强 （TGF-β），其以潜在的生物学活性储存在软骨基质中。 非活性形式（LTGF-β）。 转氨酶（TGase）催化 独特的蛋白质翻译后修饰， 在各种组织中的生物效应。 TGase最近被鉴定为 矿化生长板软骨细胞 虽然TGase参与了 细胞衰老和其他组织中的LTGF-beta激活过程，其作用 关节软骨的损伤仍不明确。 申请人的实验室 发现了惊人的高水平的活性TGase和II型TGase蛋白 与年轻猪的软骨细胞相比， 猪 TGase的抑制剂抑制PPi的加工并降低PPi的水平。 活化的TGF-β分泌的老软骨细胞，条件不利于 CPPD晶体的形成。 据推测，增加TGase 在老化的关节软骨中的活性导致CPPD晶体形成， 导致退化性关节炎 因此，本申请 提出：1）通过以下方法检查TGase在CPPD沉积中的功能： 探索其在LTGF-β激活、细胞外基质调节、 和ACV诱导的矿化; 2）探讨 通过调节猪关节软骨中TGase活性的因素 CPPD晶体形成;和3）将这些发现扩展到老年人 关节软骨和受CPPD疾病影响的软骨。 的目标 这些研究是为了了解TGase在衰老中的作用和调节， 关节软骨，因为它涉及CPPD沉积疾病。 这 多功能酶代表了新药理学的新靶点， 针对这种常见的退行性疾病的药物， 人口迅速老龄化。

DESCRIPTION (Adapted from the Applicant's Abstract): Calcium pyrophosphate dihydrate (CPPD) deposition disease is a common form of degenerative arthritis that preferentially affects the elderly. The causes of CPPD crystal formation in aging articular cartilage are unknown, although many similarities exist between processes of normal cartilage mineralization in growth plate and those of pathologic mineralizing causing CPPD disease. Current evidence suggests that CPPD crystal formation results from excess elaboration of inorganic pyrophosphate (PPi) by chondrocytes, and occurs in or around articular cartilage vesicles (ACVs) and at sites of altered cartilage matrix. The processes known to promote CPPD crystal formation are strongly and uniquely enhanced by transforming growth factor beta (TGF-beta), which is stored in cartilage matrix in a latent biologically inactive form (LTGF-beta). The enzyme transglutaminase (TGase) catalyzes a unique post-translational modification of proteins, resulting in diverse biological effects in various tissues. TGase has recently been identified in mineralizing growth plate chondrocytes. Although TGase participates in processes of cell aging and LTGF-beta activation in other tissues, its role in articular cartilage remains undefined. The applicant's laboratory discovered strikingly high levels of active TGase and type II TGase protein in articular chondrocytes from old pigs compared to chondrocytes from young pigs. Inhibitors of TGase suppress PPi elaboration and reduce levels of activated TGF-beta secreted by old chondrocytes, conditions unfavorable to the formation of CPPD crystals. It is hypothesized that increased TGase activity in aging articular cartilage leads to CPPD crystal formation and the resultant degenerative arthritis. As a consequence, this application proposes to: 1) examine the function of TGase in CPPD deposition by exploring its role in LTGF-beta activation, extracellular matrix modulation, and ACV-induced mineralization in a porcine model; 2) explore the regulation of TGase activity in porcine articular cartilage by factors which modulate CPPD crystal formation; and 3) extend these findings to aging human articular cartilage and cartilage affected by CPPD disease. The goal of these studies is to understand the role and regulation of TGase in aging articular cartilage as it relates to CPPD deposition disease. This multifunctional enzyme represents a novel target for new pharmacologic agents directed against this common degenerative disease affecting our rapidly aging population.