SPCA1在脑缺血再灌注损伤中的表达及其作用机制研究

Ischemia-reperfusion injury caused severe neural cells death and neurological deficit which is associated with a loss of cytosolic calcium homeostasis. However, the pathophysiologic mechanisms involved in ischemia-reperfusion injury are far from clear. Recent evidence highlights the functional importance of the Golgi apparatus(GA) as a major cellular Ca2+ reservoir, facilitating cellular ion homeostasis. Given that, our group presents a new concept of "GA stress" to explain the novel role of GA in oxidative stress response. SPCA1 can transport Ca2+ into the Golgi lumen and therefore is involved in the cytosolic and intra-Golgi Ca2+ homeostasis. It has shown that both of the mRNA and protein of SPCA1 are highly expressed in brain. In addition, brain is the region with the highest activity of SPCA isoforms. Moreover, SPCA1 plays the pivotal role of for normal neural development and differentiation. Interestingly, during postnatal development, the SPCA1 pump was found to be constantly highly expressed in cortex, hippocampus,and cerebellum,which happen to be the sensitive areas in ischemia. All these findings suggested that SPCA1 may be related to the involvement of Ca2+ homeostasis in neurological disorders such as ischemic. The objective of our study is to explore the intricate role of the SPCA1 pumps in ischemia-reperfusion injury. We are interested in gaining insight into the functional and expression alternation of SPCA1 pump as well as the changes of Ca2+ concentration. We hope that these findings will provide a brandnew therapeutic targets for the treatment of a broad range of pathologic disorders associated with cerebral ischemia-reperfusion injury.

缺血再灌注损伤是造成神经细胞死亡、神经功能缺损的重要原因，其复杂的损伤机制中就包括钙超载。既往认为高尔基体对钙离子稳态的调节作用较小，然而最新的研究结果表明，高尔基体同样在维持胞内钙稳态中有着重要作用，高尔基体在氧化应激中扮演的角色也日益受到重视。研究表明，SPCA1对高尔基体内及胞浆内钙离子浓度变化有着调节作用。SPCA1在脑组织中高表达并伴随着高活性，且在神经元的发育、迁移、形态发生中起着重要作用；另外神经系统发育过程中SPCA1持续性高表达的区域如海马、皮质、小脑恰好是对缺血最敏感的部位，以上均提示SPCA1在维持高尔基体功能和在神经系统疾病中的重要性。我们拟制备脑缺血再灌注细胞模型，研究SPCA1在脑缺血再灌注损伤后的表达及功能、钙离子浓度变化等并探讨其保护作用机制，为脑缺血再灌注损伤的防治提供新思路和新靶点。

钙超载是缺血再灌注损伤中的重要损伤机制。本研究课题通过干预SPCA1的表达，构建过表达SPCA1组、抑制SPCA1表达组，以OGD/R中SPCA1酶活性的改变、及其介导的细胞内外钙离子浓度变化、蛋白及基因表达水平、细胞凋亡等为评价目标，研究定位于高尔基体的钙离子泵 SPCA1在体外脑缺血再灌注模型中发挥的作用。我们在研究中阐明了SPCA1在细胞中的重要作用，定位于高尔基体的SPCA1，不仅仅能维持正常的高尔基体形态结构，同时，参与调控了细胞内钙离子浓度，是细胞不可或缺的结构蛋白和功能蛋白；在OGD/R中，其表达和功能的异常导致了细胞内钙超载，从而引起细胞凋亡和组织损伤；抑制SPCA1的表达不仅仅会造成细胞结构的破坏，更重要的，会加重钙超载；我们的研究阐明了高尔基体应激在缺血性脑卒中中的作用，为脑梗死在亚细胞结构层面的干预提供新思路和新靶点。本课题研究共发表SCI论文2篇，共培养硕博士研究生2人。项目预算安排符合规定，完成了各项计划和任务，圆满结题。