Chondrocyte-pericellular matrix derived signaling maintains tissue integrity in the temporomandibular joint

摘要 软骨细胞-细胞周基质来源的信号传导维持颞下颌关节组织的完整性 联合 颞下颌关节紊乱病影响3-7%的人口。颞下颌关节髁突软骨的完整性是颞下颌关节的核心 健康和许多TMD与其退化有关。退行性关节的病理生理学 颞下颌关节疾病（DJD）是不明确的，现代的临床干预分子靶点还没有， 被确定。软骨细胞-细胞周基质来源的信号传导是已知的软骨稳态调节剂 它代表了DJD的一个有希望的潜在治疗靶点。细胞周膜的主要成分 TMJ中的基质是VI型胶原。神经/神经胶质抗原2（NG 2）是VI型胶原蛋白的已知受体，但 NG 2-VI型胶原蛋白的相互作用尚未在下颌髁突软骨中详细研究。在其他细胞 NG 2-细胞周基质相互作用是细胞增殖，分化， 迁移和生存能力。我们的初步数据说明：a）NG 2与VI型胶原蛋白在健康人中共定位， TMJ中的关节软骨细胞，B）这种共定位在变性过程中被破坏，c） 退行性变化与高水平的内化NG 2相关，d）并且内化NG 2 与氧化应激标志物OMI/HtrA 2密切相关。我们假设软骨退化 在TMJ中，DJD部分由NG 2胞外域的蛋白水解切割、活化和内化介导 通过OMI/Htra 2途径调节氧化应激。我们将以两个具体目标来检验这一假设。在 目的1，我们将通过连接软骨，在NG 2激活和内化中涉及胞外域蛋白水解， 在野生型和蛋白酶敲除小鼠中NG 2内化的变性和测量的蛋白酶水平 和细胞。在目标2中，我们将通过连接软骨，将NG 2的功能定义为氧化应激的介体。 在野生型和NG 2基因敲除小鼠中用氧化应激、ER应激和自噬标记物进行变性 和细胞。总之，这些目标定义和评估一个全新的分子机制，软骨细胞 与已知导致TMD的机械和代谢氧化应激相关的功能。长 总之，我们试图利用这些数据来解决与确定TMD精确方法相关的临床问题 分类、预防和治疗。

ABSTRACT Chondrocyte-pericellular matrix derived signaling maintains tissue integrity in the temporomandibular joint Temporomandibular disorders affect 3-7% of the population. TMJ condylar cartilage integrity is central to TMJ health and many TMDs are associated with its degeneration. The pathophysiology of degenerative joint disease (DJD) in the TMJ is ill-defined and contemporary molecular targets for clinical intervention have yet to be determined. Chondrocyte-pericellular matrix derived signaling is a known regulator of cartilage homeostasis and it represents a promising potential therapeutic target for DJD. The major component of the pericellular matrix in the TMJ is type VI collagen. Nerve/glial antigen 2 (NG2) is a known receptor of type VI collagen, but NG2-type VI collagen interactions have not been studied in detail in mandibular condylar cartilage. In other cell types, the NG2-pericellular matrix interactions are a critical regulator of cell proliferation, differentiation, migration, and viability. Our preliminary data illustrate that a) NG2 colocalizes with type VI collagen in healthy articular chondrocytes in the TMJ, b) that this colocalization is disrupted during degeneration, c) that degenerative changes are associated with high levels of internalized NG2, d) and that internalized NG2 is closely associated with a marker for oxidative stress, OMI/HtrA2. We hypothesize that cartilage degeneration in TMJ DJD is mediated, in part, by proteolytic cleavage of the NG2 ectodomain, activation, and internalization to regulate oxidative stress through OMI/Htra2 pathway. We will test this hypothesis with two specific aims. In aim 1, we will implicate ectodomain proteolysis in NG2 activation and internalization by linking cartilage degeneration with NG2 internalization and measured protease levels in wild-type and protease knockout mice and cells. In aim 2, we will define the functionality of NG2 as a mediator of oxidative stress by linking cartilage degeneration with markers of oxidative stress, ER stress, and autophagy in wild-type and NG2 knockout mice and cells. Together, these aims define and evaluate an entirely novel molecular mechanism of chondrocyte function that is contextually linked to mechanical and metabolic oxidative stresses known to cause TMDs. Long term, we seek to use these data to solve clinical problems associated with defining precise methods of TMD classification, prevention, and treatment.