GRP78及其家族的应激表达对高原缺氧条件下机体损伤机制的探讨

Discussion on Mechanism of Stress Expression of GRP78 and Its Family on Body Injury under High Altitude Hypoxia

目的研究葡萄糖调节蛋白-78(glucose-regulatory protein-78,GRP78)及其家族的应激表达对高原缺氧机体组织的指示性作用及其机制。方法以首次登录3700 m海拔的高原地区的6名汉族人群(男女各半,以30~35岁组、50~55岁组、60~62岁组)进行,以飞机进藏方式,中间不进行间隔修整直接由重庆主城区(海拔高度多在168~400 m之间)直飞拉萨贡嘎机场(3713 m海拔),在3000~5013 m海拔进行十余天的跟踪采血采样,通过ELISA酶联免疫检测法检测血清及血浆中的GRP78、HIF-1α、热休克蛋白70(heat shock proteins 70,HSP70)等热敏休克蛋白的表达变化情况。结果与出发前预留血样相比,进藏人群血样中的GRP78(只限女性)、HSP70等热敏休克蛋白的表达均显著增加(P<0.05),女性各年龄组的GRP78、HSP70等热敏休克蛋白的表达表达峰值较同年龄组的男性达峰更早,持续时间更短。且在GRP78的表达中存在性别差异,女性各时间段各组OD值存在显著差异(P<0.05)。年轻人群因活动量较大,所以表达强度较中年、老年人群强烈。在第10日,因为机体适应能力较强会造成表达强度开始大幅度低于中老年组有统计学意义(P<0.05)。结论女性的GRP78的3 d内表达的强弱更多提示机体对高原反应的初始适应情况,而3~10 d的持续性表达强度对在高原地区的长期生存适应具有一定的指示性作用。GRP78的高表达能够减轻高原缺氧对心脑组织的损伤,作用机制可能与其在缺氧作用下一级氨基酸序列LIGRTWNDPSVQQDOKFL(Leu98-Leu115)是α2巨球蛋白(α2M)的结合位点,这有利于细胞外调节蛋白激酶(extracellular regulated protein kinases,ERK)和蛋白激酶B(protein kinase B,PKB又称AKT)信号传导活化,增加DNA和蛋白质合成,从而促进细胞增殖和存活。同时可能也与激活Nrf2/HO-1信号途径,提高抗氧化酶活性,降低机体氧化应激改善能量代谢有关。

Objective To investigate the indicative effect and mechanism of GRP78 and its family stress expression on high altitude hypoxia.Methods 6 Han ethnic groups(half male and half female,30~35 years old group,50~55 years old group,60~62 years old group)who landed at a high plateau area at an altitude of 3,700 meters for the first time,flew directly from the main urban area of Chongqing(at an altitude between 168~400 meters)directly to Lhasa Gongga Airport(at an altitude of 3713 meters)without interval repair by aircrafts.Follow-up blood sampling was conducted at an altitude of 3,000 to 5,013 meters for more than 10 days.The expression of heat-sensitive shock proteins such as GRP78,HIF-1 and HSP70 in serum and plasma was detected by enzyme-linked immunosorbent assay.Results Compared with the reserved blood samples before departure,the expression of thermo-shock proteins such as GRP78(female only)and HSP70 in the blood samples of the Tibetan population increased significantly(P<0.05).The expression peaks of heat-sensitive shock proteins such as GRP78 and HSP70 in females in each age group reached the peak earlier and lasted shorter than those in males in the same age group.There was also a gender difference in the expression of GRP78,and there was significant difference in the OD value of each time period in women(P<0.05).The expression intensity in young people is stronger than that in middle-aged and elderly people because of the large amount of activity.On the tenth day,because of the strong adaptability of the body,the expression intensity began to be significantly lower than that of the middle-aged and elderly group(P<0.05).Conclusion The expression intensity of GRP78 in females within 3 days is more suggestive of the initial adaptation of the body to altitude reaction,and the sustained expression intensity from 3 to 10 days has a certain indicative effect on long-term survival adaptation in high altitude areas.The high expression of GRP78 can alleviate the damage of high altitude hypoxia to cardio-cerebral tissue,and the mechanism of action may be related to its primary amino acid sequence LIGRTWNDPSVQQDOKFL(Leu98-Leu115)under hypoxia as the binding site ofα2M,which is conducive to ERK and AKT signaling activation,increases DNA and protein synthesis,and thus promotes cell proliferation and survival.At the same time,it may also be related to the activation of Nrf2/HO-1 signaling pathways,improving antioxidant enzyme activity,reducing oxidative stress and improving energy metabolism.