SERCA2 C674的失活与动脉粥样硬化的关系及调控机制

Atherosclerosis is the leading cause of death and poses an increasing threat to human health worldwide. Knowledge of the related regulation mechanism of atherosclerosis may have significance for understanding the causes of the diseases, and could be helpful for rational design of novel therapeutic and diagnostic methods. Sarco/endoplasmic reticulum calcium ATPase 2 (SERCA2) is critical to maintain calcium homeostasis in the endoplasmic reticulum (ER). Cysteine 674 (C674) is the main redox site of SERCA2, which plays a key role in regulating SERCA2 activity. Under pathological conditions, however, C674 is easily irreversibly oxidized and fails to stimulate SERCA2 activity, which suggested to be related with the pathogenesis of atherosclerosis. Using SERCA2 C674S knock-in mice (SKI) to mimic the inactivation of C674 in pathological conditions, we found that SKI significantly accelerated the formation of atherosclerotic plaque, suggesting inactivation of C674 is directly involved in the pathogenesis of atherosclerosis. Moreover, SKI decreased the level of insulin receptor in macrophage, while CHOP (C/EBP homologous protein) was up-regulated, which revealed the regulation of SKI on these genes may partially mediated the occurrence of atherosclerosis. In this project, using SKI and CHOP knockout mice, we will investigate the effect of SERCA2 C674 inactivation on atherosclerosis in macrophage, and explore the potential mechanism involved thus providing new theory and therapeutic target for clinical prevention and treatment of atherosclerosis.

肌浆网/内质网钙ATP酶2对维持内质网钙稳态至关重要。位于674位的半胱氨酸(C674)是SERCA2的主要氧化还原位点，在形成动脉粥样硬化的病理条件下，其不可逆性氧化可以抑制SERCA2的功能,推测与动脉粥样硬化的形成有关。利用SERCA2 C674S 基因敲入鼠(SKI)来模拟这个位点的失活，我们发现SKI促进动脉粥样斑块的生成，表明SERCA2 C674的失活直接参与了动脉粥样硬化的进程。在巨噬细胞上，SKI下调胰岛素受体水平，上调CHOP的表达，推测SKI对这些基因的调控参与了动脉粥样硬化的进程。利用SKI和CHOP敲除小鼠，本课题拟从巨噬细胞角度探讨C674的失活与动脉粥样硬化的关系及调控机制，为动脉粥样硬化的防治提供新的理论依据和干预靶点。

在动脉粥样硬化患者和形成动脉粥样硬化小鼠模型的血管中，SERCA2 C674的不可逆性氧化明显增加，但SERCA2 C674的不可逆性氧化与动脉粥样硬化的关系及其调控机制目前还不清楚。本项目主要利用SERCA2 C674S基因敲入鼠（SERCA2 C674S knock-in mice，SKI），从巨噬细胞的角度探讨SERCA2 C674失活是否通过干扰细胞内钙稳态来影响巨噬细胞功能和动脉粥样硬化。我们发现SERCA2 C674失活可以激活内质网应激，促进炎性反应，加剧动脉粥样硬化，而内质网应激抑制剂4-PBA可以减轻SERCA2 C674失活引起的内质网应激，抑制炎性反应，改善动脉粥样硬化。SERCA是唯一将Ca2+从胞浆摄入到肌浆网/内质网的主动转运体，维持细胞内钙稳态。我们发现SERCA2 C674失活可以导致线粒体钙超载，干扰线粒体能量代谢。为此我们构建了线粒体ATP的实时成像分析方法，可用于线粒体能量代谢相关疾病的诊断。我们的研究一方面明确了SERCA2 C674失活促进动脉粥样硬化发生的分子机制，提出了内质网应激可以作为动脉粥样硬化治疗的干预靶点，另一方面我们也发现SERCA2 C674失活可以导致线粒体功能障碍，参与心血管疾病的发生。

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