Decline in the expression of IL-2 after trauma and changes in the nuclear transcription factors NFAT and AP-1

创伤后IL-2表达受抑与核转录因子NFAT,AP-1变化的关系(英文)

OBJECTIVE: To investigate whether the decrease in expression of interleukin-2 (IL-2) after trauma is associated with changes in DNA binding activity of nuclear factor of activated T cells (NFAT) and activator protein-1 (AP-1). METHODS: Mice with closed impact injury with fracture in both hind limbs were adopted as the trauma model. Spleen lymphocytes were isolated from traumatized mice and stimulated with Con-A. Culture supernatants were assayed for IL-2 activity, and total RNA was extracted from spleen lymphocytes and assayed for IL-2 mRNA. DNA binding activity of NFAT and AP-1 were measured by electrophoretic mobility shift assay (EMSA). The expression of c-Fos, c-Jun and JunB proteins was determined by the Western blot analysis. RESULTS: DNA binding activity of NFAT and AP-1 gradually decreased to a minimum of 41% and 49%, respectively, of the control on the 4th day after injury, which was closely followed by the decline in IL-2 activity and IL-2 mRNA. A decrease in the expression of c-Fos on the 1st and 4th day after trauma had no significant effect on c-Jun expression; the increase in expression of JunB was only on the 1st day after injury. CONCLUSION: Decreased IL-2 expression is, at least in part, due to a decline in the activation of NFAT and AP-1 in traumatized mice. The decline in DNA binding activity of NFAT and AP-1 is partly due to a trauma-induced block in the expression of c-Fos.

目的 探讨创伤后脾细胞活化T细胞核因子 (nuclearfactorofactivatedTcells,NFAT)和激活蛋白 1(activatorprotein 1,AP 1)的DNA结合活性、部分家族成员c Fos ,c Jun和JunB蛋白的表达和白细胞介素 2 (IL 2 )表达的动态变化及它们间的关系。方法 采用小鼠双后肢闭合性砸伤 +骨折模型 ,于创伤后 6h、12h、1、4、7、10和 14天处死动物 ,分离脾细胞 ,经ConA刺激细胞后收集培养上清以测定IL 2活性 ;提取脾细胞RNA以测定IL 2mRNA ;提取脾细胞核蛋白 ,用电泳迁移率改变试验 (electrophoreticmobilityshiftassay ,EMSA)检测NFAT和AP 1的DNA结合活性。用免疫蛋白印迹法 (Westernblotassay)检测c Fos,c Jun和JunB蛋白的表达。结果 和正常对照组相比 ,创伤后IL 2活性、IL 2mRNA均有不同程度的降低 ,其受抑的程度在创伤后 4天更为明显。创伤后脾细胞NFAT和AP 1的DNA结合活性亦逐渐下降 ,至伤后 4天时下降最明显 ,为正常对照组的4 1%和 4 9%。这与创伤后脾细胞IL 2的活性和IL 2mRNA的降低相一致。c Fos蛋白水平在伤后 1和 4天明显降低 ;c Jun蛋白表达无明显变化 ;JunB蛋白水平仅在伤后 1天明显表达。结论 上述结果提示 ,创伤后脾细胞IL 2表达受抑至少部分上是由于核转录因子NFAT和AP 1的DNA结合活性降低所导致 ;