Duraj J, Kovacikova M, Sedlak J, Koppel J, Sobel A, Chorvath B
Department of Molecular Immunology, Slovak Academy of Sciences, Bratislava.
Leuk Res. 1995 Jul;19(7):457-61. doi: 10.1016/0145-2126(94)00154-3.
The human pre-B acute lymphoblastic leukemia cell line REH6 was used to analyze the regulation of a ubiquitous intracellular phosphoprotein stathmin (Mr 19,000, pl = 5.6-6.2). We demonstrated by 32P-labeling that the short (1 h) treatment of the REH6 cells with the tumor promoting phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), resulted in a rapid phosphorylation of at least three (P1, P2 and P3) stathmin isoforms without an alteration of stathmin isoform expression. Furthermore, Western blot analysis with specific antiserum showed that the prolonged period (48 h) of TPA treatment partially reduced protein levels particularly of two (N2 and P2) stathmin isoforms. The potent and relatively specific protein kinase C (PKC) inhibitor, 1,(5-isoquinolinesulphonyl)2methylpiperasine dihydrochloride (H7), partially inhibited these TPA effects, whereas the specific calmodulin inhibitor R24571 (calmidazolium) had no effect upon these events. Our findings suggest that stathmin phosphorylation in REH6 cells could be in part mediated by PKC activation.
人类前B急性淋巴细胞白血病细胞系REH6被用于分析一种普遍存在的细胞内磷蛋白——微管解聚蛋白（分子量19,000，等电点=5.6 - 6.2）的调控机制。我们通过³²P标记证明，用促肿瘤佛波酯12 - O - 十四烷酰佛波醇-13 - 乙酸酯（TPA）对REH6细胞进行短时间（1小时）处理，会导致至少三种微管解聚蛋白异构体（P1、P2和P3）快速磷酸化，而微管解聚蛋白异构体的表达没有改变。此外，用特异性抗血清进行的蛋白质免疫印迹分析表明，TPA长时间（48小时）处理会部分降低蛋白质水平，特别是两种微管解聚蛋白异构体（N2和P2）的水平。强效且相对特异的蛋白激酶C（PKC）抑制剂1,（5 - 异喹啉磺酰基）-2 - 甲基哌嗪二盐酸盐（H7）部分抑制了这些TPA效应，而特异性钙调蛋白抑制剂R24571（卡咪唑）对这些事件没有影响。我们的研究结果表明，REH6细胞中微管解聚蛋白的磷酸化可能部分由PKC激活介导。
