微丝重组对PKⅡ和PKA活性的影响

THE EFFECT OF THE REORGANIZATION OF MICROFILAMENTS ON ACTIVITY OF PKⅡ AND PKA

利用微丝解聚药物──细胞松弛素Ｂ（ＣＢ）对Ｇ０期小鼠Ｃ３Ｈ（１０）Ｔ１／２成纤维细胞进行预处理，就微丝重组对细胞进入Ｓ期，进行ＤＮＡ合成及蛋白激酶Ⅱ（ＰＫⅡ）和蛋白激酶Ａ（ＰＫＡ）的活性变化进行了研究。ＣＢ处理可促进细胞进入Ｓ期，增强ＤＮＡ合成。当细胞进入晚Ｇ１期时，ＰＫⅡ活性显著上升，且核内ＰＫⅡ活性上升速度更快，超过细胞质部分。细胞进入Ｓ期后，ＰＫⅡ活性维持在晚Ｇ１期的高水平上，而ＰＫＡ的活性变化趋势与ＰＫⅡ相反，细胞进入Ｓ期后，其活性明显下降。ＣＢ预处理可刺激ＰＫⅡ活性，抑制ＰＫＡ活性，表明ＣＢ处理刺激细胞进入Ｓ期可能与ＰＫⅡ和ＰＫＡ在细胞周期进程中的活性变化有关，ＰＫⅡ与ＰＫＡ之间可能以相互颉抗方式参与调节。

The effects of the reoraganization of microfilaments on initiation of DNA synthesis and activity of PKⅡ and PKA in C3H10T1/2 cells by treatment with microfilament destroying drug -cytochalasin B(CB) were studied.A acceleration of progression from G1 to S phase and promotion of DNA synthesis were observed in quiesoent cells treated with 3 mg·L-1 CB for 2h.While the activity of PKⅡ increased markedly in late G1 stage, in the nucleus a higher level than in cytoplasm was found in the enzyme activity.In DNA synthesis stage the PKⅡ activity remained constant as in late G1 stage.It is found that the activity of PKⅡ in cells exposed to CB 2h was enhanced in late G1 stage.However,after entry into S phase,the PKA activity reduced obviously. It is noteworthy that in S phase the activity of PKA was inhibited further by treatment with CB.The results raise the possibility that the promotion of entry of quiescent cells into S phase by treatment with CB may be related to the changes of the activity of PKⅡ and PKA in the progression from G1 to S phase.