Kraus S, Seger R, Fishelson Z
Department of Cell Biology and Histology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Clin Exp Immunol. 2001 Mar;123(3):366-74. doi: 10.1046/j.1365-2249.2001.01477.x.
Sublytic doses of complement desensitize cells and make them resistant to lytic complement doses. This process, named complement-induced protection, requires calcium ion influx, protein kinase C activation and protein synthesis. The involvement of the extracellular signal-regulated kinase, ERK, in cell desensitization by sublytic complement was examined in erythroleukaemia K562 cells and in COS-7 cells. As shown here, ERK is activated in K562 and COS-7 cells within 10 min of sublytic immune attack and then shows a decline and a second peak of activation at 20 min. C7- and C8-deficient human sera have a small effect on ERK activity. However, a significant increase in ERK activation is observed when C7 or C8, respectively, is added back to these sera. Complement-induced ERK activation was blocked in cells treated with GF109203X or Go6976, two selective PKC inhibitors, as well as by treatment with PD098059, an inhibitor of MEK1, the ERK kinase. PD098059 treatment also sensitized K562 cells to complement-mediated lysis and prevented complement-induced protection. COS-7 cells transfected with a dominant-negative MEK plasmid were incapable of undergoing the process of complement-induced protection. In conclusion, cell desensitization by sublytic doses of the complement membrane attack complex involves a signalling cascade that includes PKC-mediated ERK activation.
亚溶剂量的补体可使细胞脱敏并使其对溶细胞补体剂量产生抗性。这一过程，即补体诱导的保护作用，需要钙离子内流、蛋白激酶C激活和蛋白质合成。在红白血病K562细胞和COS-7细胞中研究了细胞外信号调节激酶（ERK）在亚溶补体引起的细胞脱敏中的作用。如下所示，在亚溶免疫攻击后10分钟内，ERK在K562和COS-7细胞中被激活，然后在20分钟时活性下降并出现第二个激活峰。C7和C8缺陷的人血清对ERK活性影响较小。然而，当分别将C7或C8添加回这些血清中时，观察到ERK激活显著增加。在用两种选择性PKC抑制剂GF109203X或Go6976处理的细胞中，以及在用ERK激酶MEK1的抑制剂PD098059处理的细胞中，补体诱导的ERK激活被阻断。PD098059处理还使K562细胞对补体介导的裂解敏感，并阻止补体诱导的保护作用。用显性负性MEK质粒转染的COS-7细胞无法进行补体诱导的保护过程。总之，亚溶剂量的补体膜攻击复合物引起的细胞脱敏涉及一个信号级联反应，其中包括PKC介导的ERK激活。
