2-氯乙醇经NMDAR/cAMP/PKA信号通路致星形胶质细胞AQP4蛋白表达增强

2-Chloroethanol enhanced the expression of AQP4 protein in astrocytes via NMDAR/cAMP/PKA signaling pathway

目的探讨N-甲基-D-天冬氨酸受体(NMDAR)/环磷酸腺苷(cAMP)/cAMP依赖性蛋白激酶A(PKA)信号通路在2-氯乙醇上调星形胶质细胞(AS)表达水通道蛋白-4(AQP4)中的作用。方法①取对数生长期的AS予剂量为0.0、7.5、15.0和30.0 mmol/L 2-氯乙醇(设为相应剂量组)刺激12 h后,收集细胞进行检测。②取对数生长期的AS为空白对照组、抑制剂(MK-801或H89)对照组、2-氯乙醇组、抑制剂(MK-801或H89)干预组。空白对照组不予任何处理;抑制剂对照组仅予浓度为10.0μmmol/L MK-801或15.0μmmol/L H89处理;MK-801干预组以浓度为10.0μmmol/L的MK-801提前干预30 min,H89干预组以浓度为15.0μmmol/L的H89提前干预1 h;干预结束后,2-氯乙醇组和MK-801、H89干预组AS均予浓度为30.0 mmol/L的2-氯乙醇刺激12 h。③收集各组AS,采用蛋白免疫印迹法和实时荧光定量聚合酶链式反应法检测AS内AQP4、NMDAR受体主亚基(NR1)、NMDAR受体2B亚基(NR2B)、钙调素依赖性蛋白激酶Ⅱ(CaMKⅡ)的蛋白和mRNA的表达,采用蛋白免疫印迹法检测磷酸化CaMKⅡ(p-CaMKⅡ)和PKA的表达;采用比色法检测AS内钙离子(Ca^(2+))浓度,采用酶联吸附试验检测腺苷酸环化酶(AC)活力和cAMP水平。结果①30.0 mmol/L剂量组AS内AQP4、NR1、NR2B的蛋白与mRNA,PKA蛋白、CaMKⅡmRNA的相对表达水平以及p-CaMKⅡ/CaMKⅡ蛋白比值、Ca^(2+)浓度、AC活力、cAMP水平均高于0.0 mmol/L剂量组(P<0.05)。PKA蛋白相对表达水平和Ca^(2+)浓度均随着2-氯乙醇剂量的增加而增加(P<0.05)。②2-氯乙醇组AS内AQP4蛋白相对表达水平、Ca^(2+)浓度均高于空白对照组和MK-801对照组(P<0.05),MK-801干预组AS内AQP4蛋白相对表达水平和Ca^(2+)浓度均低于2-氯乙醇组(P<0.05);2-氯乙醇组AS内AQP4和PKA蛋白相对表达水平均高于空白对照组和H89对照组(P<0.05),H89干预组AS内AQP4和PKA蛋白相对表达水平均低于2-氯乙醇组(P<0.05)。结论 2-氯乙醇可通过激活NMDAR/cAMP/PKA信号通路诱导AS中AQP4的表达增强。

Objective To investigate the role of N-methyl-D-aspartate receptor(NMDAR)/cyclic adenosine monophosphate(cAMP)/protein kinase A(PKA) signaling pathways in regulating 2-chloroethanol-induced aquaporin-4(AQP4) expression in astrocytes(AS). Methods i) AS in logarithmic growth phase were treated with 2-chloroethanol at the doses of 0.0, 7.5, 15.0 and 30.0 mmol/L for 12 hours, and the cells were collected for detection. ii) The AS in logarithmic growth phase were divided into blank control group, inhibitor control group, 2-chloroethanol group, and inhibitor intervention group. The inhibitor included dizocilpine(MK-801) and N-(2-[p-bromocinnamylamino-]ethyl)-5-isoquinolinesulfonamide(H89). The blank control group did not receive any treatment. The inhibitor control group was treated with a concentration of 10.0 μmmol/L MK-801 or 15.0 μmmol/L H89. The MK-801 intervention group was pretreated with MK-801 at a concentration of 10.0 μmmol/L for 30 minutes. The H89 intervention group was pretreated with H89 at a concentration of 15.0 μmmol/L for 1 hour. After the intervention, the AS in 2-chloroethanol group and MK-801, H89 intervention group were stimulated with 2-chloroethanol at a dose of 30.0 mmol/L for 12 hours. iii) The AS in each group were collected and used for Western blotting and real-time fluorescence quantitative polymerase chain reaction analysis to detect the protein and mRNA expression of AQP4, NMDAR receptor main subunit(NR1), NMDAR receptor 2 B subunit(NR2 B) and calmodulin dependent protein kinaseⅡ(CaMKⅡ). The Western blotting was adopted to detect the expression of phosphorylase-CaMKⅡ(p-CaMKⅡ) and PKA. Colorimetric method was used to detect the concentration of calcium(Ca^2+) in AS. The enzyme-linked adsorption test was used to measure adenylate cyclase(AC) activity and cAMP levels. Results i) The relative expression of protein and mRNA of AQP4, NR1 and NR2 B, PKA at protein level and CaMKⅡ at mRNA level, and the ratio of p-CaMKⅡ/CaMKⅡ protein, the concentration of Ca^2+, AC activity and cAMP level in 30.0 mmol/L group were higher then those of 0.0 mmol/L group in AS(P<0.05). The relative protein expression of PKA and the concentration of Ca^2+ increased with the increase of 2-chloroethanol(P<0.05). ii) The relative protein expression of AQP4 and the concentration of Ca^2+ in the 2-chloroethanol group were higher than that of the blank control group and MK-801 control group(P<0.05). The relative protein expression of AQP4 and the concentration of Ca^2+ in MK-801 intervention group were lower than that in 2-chloroethanol group(P<0.05). The relative protein expression of AQP4 and PKA in 2-chloroethanol group were higher than that of the blank control group and H89 control group(P<0.05). The relative protein expression of AQP4 and PKA in H89 intervention group was lower than that in 2-chloroethanol group(P<0.05). Conclusion The 2-chloroethanol timulation induces the expression of AQP4 by activating NMDAR/cAMP/PKA signaling pathway in AS.