T-VSCC钙离子通道参与介导力学过载诱发软骨细胞病理性肥大化的机制研究

Mechanical loading is crucial for the regulation of cartilage morphology and function. Physiological mechanical loading maintains proper function of chondrocytes, whereas prolonged pathological mechanical overloading has negative impact on chondrocyte phenotype. Previous studies demonstrated that mechanical overloading induces articular cartilage degeneration through initiating chondrocyte hypertrophy. However, the underlying mechano-transduction process of mechanical overloading is still largely unknown. Our previous study showed a significantly up-regulated T-type voltage sensitive calcium channel (T-VSCC) protein level in hypertrophic chondrocytes located in medial cartilage of varus knees, suggesting T-VSCC might play a central role in mechanical overloading induced chondrocyte hypertrophy. Based on the data of preliminary research，we propose our hypothesis: mechanical overloading up-regulates T-VSCC expression level in chondrocyte, enhances [Ca2+]i and initiates hypertrophic process through Nuclear factor of activated T-cells (NFAT) dephosphorylation. In the present study, we aim to demonstrate the regulation effect of mechanical overloading up-regulated T-VSCC expression and protein levels by establishing in-vitro and in-vivo models. With these models, the role of T-VSCC in mechanical overloading induced chondrocyte hypertrophy will be investigated. By exploring the relationship between T-VSCC up-regulation induced [Ca2+]i signal and NFAT dephosphorylation, the underlying mechanism of T-VSCC mediated mechanical overloading induced chondrocyte hypertrophy will be uncovered. The conclusion of present study will provide new insight into molecular mechanism of chondrocyte mechano-transduction, as well as possible intervention target for mechanical overloading induced cartilage degeneration.

力学刺激是调控软骨形态与功能的重要因素：生理水平力学刺激维持软骨细胞正常功能，但非生理的长期力学过载对其表型维护起负面作用。既往研究表明，力学过载通过启动软骨细胞肥大化进程诱发软骨退变，但其中的转导机制不清。我们前期发现：内翻膝高应力退变区域软骨细胞病理性肥大化且T型电压门控钙离子通道（T-VSCC）高表达，其可能介导力学过载诱发的软骨细胞肥大化。在进一步预实验基础上，我们提出假说：力学过载通过上调T-VSCC表达，增强[Ca2+]i信号，并经由活化T细胞因子（NFAT）启动病理性肥大化。本项目拟建立力学过载模型考察力学刺激对T-VSCC的调控作用，分析T-VSCC在力学过载诱导软骨细胞病理性肥大化中的介导作用，阐明T-VSCC上调后的[Ca2+]i信号对NFAT的调控机制验证假说。本项目的结论有望为阐明软骨细胞内力学信号转导机制提供新观点；并为力学过载诱发软骨退变的治疗提供潜在干预靶点。

力学刺激是调控软骨形态与功能的重要因素：生理水平力学刺激维持软骨细胞正常功能，但非生理的长期力学过载对其表型维护起负面作用。既往研究表明，力学过载通过启动软骨细胞肥大化进程诱发软骨退变，但其中的转导机制不清。本项目通过构建力学过载动物模型与体外细胞模型，借助免疫组化、PCR、WB等检测手段，逐步完成本项目研究内容：（1）完成力学刺激模型建立与验证；以及力学过载对软骨细胞肥大化及对T-VSCC水平的调控作用；（2）T-VSCC在软骨细胞透明软骨表型中的调控作用；（3）T-VSCC调控软骨细胞表型的作用机制，最终发现T-VDCC亚型蛋白Cav3.3通过调控下游钙离子信号发生及NFAT信号通路活化，在关节软骨细胞透明软骨表型维持中具有重要调控作用。本项目的结论为阐明关节软骨细胞内力学信号转导机制提供新观点；并为力学过载诱发软骨退变的治疗提供了潜在干预靶点。截止目前，本项目累计参加国内外会议大会发言 2 次；在国际刊物发表 SCI 论文 4 篇，其中1篇论文获得全美排名第一骨科专科医院（HSS）Peter Torzilli 教授推荐入选 Faculty Opinions （评价指数“非常好”）；申请国家发明专利 1 项，培养博士研究生1名。

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