Integrin/FAK信号通路在下颌髁突软骨细胞力学信号转导中的分子机制研究

Mechanical micro-environment change is the main reason of Temporomandibular joint (TMJ) degeneration and Temporomandibular Disorders(TMD). TMJ is the only joint that maintains lifelong ability of reconstruction among all of the human joints, and mandibular condylar chondrocyte plays key roles in sensing mechanical stimulation and transducing signals. But how TMJ chondrocyte react to the pressure changes during TMD and the exact molecular regulatory mechanism remain unknown. It has been revealed that integrin/FAK signaling pathway is responsive to the mechanical stimulation and contributes to mechanotransduction. However, during the development of TMD, it remains largely unknown whether integrin/FAK signaling is involved. In this project, in vitro cultured mandibular condylar chondrocyte model under mechanical pressure will be used to study the relationship between integrin/FAK signaling and the alterations of cell morphology as well as cell functions under the mechanical stimulation. Then, we will use the FAK inhibitor to block the FAK signaling activity to investigate the effect of FAK signaling in mechanical stimulation-elicited chondrocyte cell maturation. Furthermore, TMJ anterior disc displacement (ADD) model will be established. By using this model, the effects of mechanical stimulation in mandibular condylar chondrocyte cell maturation will be studied and the distribution of integrin/FAK signaling in mandibular condylar chondrocyte will be determined for the role of signaling of this pathway in TMJ remodeling.

力学微环境改变是导致颞下颌关节（TMJ）软骨退变及颞下颌关节紊乱病（TMD）的主导因素。TMJ中的髁突软骨细胞（以下简称：软骨细胞）在感受力学刺激及信号传递中发挥着关键作用，但软骨细胞在TMD病理进程中如何感受压力微环境改变及其确切分子调控机制目前仍不清楚。Integrin/FAK被认为是细胞感受应力刺激及活化力学信号的重要传导通路，但其是否参与TMD软骨病理改建过程未见报道。本项目拟采用离体软骨细胞模型，研究软骨细胞在不同力学刺激作用下形态和功能的改变及其与integrin/FAK通路的关联，并通过抑制FAK活性初步探讨该信号通路在应力刺激诱导软骨细胞成熟中的作用及分子调控机制。同时，应用TMJ前移位在体动物模型观察应力刺激对关节软骨结构及integrin/FAK信号通路的影响，探讨该信号通路在TMJ适应性改建过程中的作用和功能，为阐明TMD病理机制及优化治疗方案提供实验依据。

在本研究中，采用静水压作用下的离体髁突软骨细胞模型和关节盘前移位动物模型，系统研究髁突软骨细胞在不同强度静水压及不同力值关节盘前移位作用下髁突组织细胞形态、功能及增殖凋亡活动的改变，验证应力刺激是否通过integrin- FAK- ERK/ PI3K 这条信号通路引起髁突软骨细胞内反应。细胞模型揭示本研究表明随静水压强度提高髁突软骨细胞活性显著增加，同时有效减少细胞凋亡率减少。随静水压强度增加integrinβ1mRNA转录水平显著增加,且FAK、ERK1/2及PI3K蛋白磷酸化水平也随之增加，但ERK1、 ERK2及PI3KmRNA水平未见明显变化。Cilengitide作为潜在有效的integrin抑制剂能够有效阻断上述静水压的效应。且在关节盘前移位动物模型中发现施加随施加力值的增加，micro-CT表面髁突前后前面出现不同程度的改建；integrin-FAK-ERK/PI3K信号通路参与静水压环境下髁突软骨细胞增值凋亡活动改变。进而确定髁突软骨细胞中integrin/FAK信号通路参与调控颞下颌关节适应性改建的分子机制。