Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China.
Department of Neurology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China.
Neuroscience. 2017 Aug 15;357:56-66. doi: 10.1016/j.neuroscience.2017.05.043. Epub 2017 May 31.
Zinc-α2-glycoprotein (ZAG) is a 42-kDa protein encoded by the AZGP1 gene that is known as a lipid mobilizing factor and is highly homologous to major histocompatibility complex class I family molecules. Recently, transcriptomic research has shown that AZGP1 expression is reduced in the brain tissue of epilepsy patients. However, the cellular distribution and biological role of ZAG in the brain and epilepsy are unclear. Patients with refractory temporal lobe epilepsy (TLE) and brain trauma were included in this study, and pentylenetetrazole (PTZ)-kindled rats were also used. The existence and level of ZAG in the brain were identified using immunohistochemistry, double-labeled immunofluorescence and western blot, and the expression level of AZGP1 mRNA was determined with quantitative real-time polymerase chain reaction (qrt-PCR). To explore the potential biological role of ZAG in the brain, co-immunoprecipitation (Co-IP) of phosphorylated ERK (p-ERK), TGF-β1 and ZAG was also performed. ZAG was found in the cytoplasm of neurons in brain tissue from both patients and rats. The levels of AZGP1 mRNA and ZAG were lower in refractory TLE patients and PTZ-kindled rats than in controls. In addition, the ZAG level decreased as PTZ kindling continued. Co-IP identified direct binding between p-ERK, TGF-β1 and ZAG. ZAG was found to be synthesized in neurons, and both the AZGP1 mRNA and ZAG protein levels were decreased in epilepsy patients and rat models. The reduction in ZAG may participate in the pathogenesis and pathophysiology of epilepsy by interacting with p-ERK and TGF-β1, promoting inflammation, regulating the metabolism of ketone bodies, or affecting other epilepsy-related molecules.
锌-α2-糖蛋白（ZAG）是一种 42kDa 蛋白，由 AZGP1 基因编码，被称为脂质动员因子，与主要组织相容性复合物 I 类分子高度同源。最近的转录组学研究表明，癫痫患者脑组织中 AZGP1 的表达降低。然而，ZAG 在大脑中的细胞分布和生物学作用尚不清楚。本研究纳入了难治性颞叶癫痫（TLE）和脑外伤患者，并使用戊四氮（PTZ）点燃大鼠。通过免疫组织化学、双重免疫荧光和 Western blot 鉴定大脑中 ZAG 的存在和水平，并通过实时定量聚合酶链反应（qrt-PCR）测定 AZGP1 mRNA 的表达水平。为了探讨 ZAG 在大脑中的潜在生物学作用，还进行了磷酸化 ERK（p-ERK）、TGF-β1 和 ZAG 的共免疫沉淀（Co-IP）。在患者和大鼠的脑组织中发现 ZAG 存在于神经元的细胞质中。与对照组相比，难治性 TLE 患者和 PTZ 点燃大鼠的 AZGP1 mRNA 和 ZAG 水平较低。此外，随着 PTZ 点燃的持续，ZAG 水平下降。Co-IP 鉴定了 p-ERK、TGF-β1 和 ZAG 之间的直接结合。发现 ZAG 是在神经元中合成的，并且在癫痫患者和大鼠模型中，AZGP1 mRNA 和 ZAG 蛋白水平均降低。ZAG 的减少可能通过与 p-ERK 和 TGF-β1 相互作用，促进炎症、调节酮体代谢或影响其他与癫痫相关的分子，参与癫痫的发病机制和病理生理学。
