Grdisa M
Division of Molecular Medicine, Ruder Bosković Institute, Zagreb, Croatia.
Cell Biochem Funct. 1998 Dec;16(4):277-82. doi: 10.1002/(SICI)1099-0844(1998120)16:4<277::AID-CBF798>3.0.CO;2-D.
After treatment of HD3 cells with erythroid-inducing agents (hemin and butyric acid) at 42 degrees C, the profile of phosphotyrosine-containing proteins was altered. Upon induction the overall level of phosphotyrosine-containing proteins increased. To examine the role of protein phosphorylation in HD3 cells differentiation, the cells were treated with specific inhibitors. In the presence of okadaic acid, cell proliferation was arrested and accompanied by a marked increase in haemoglobin synthesis, a differentiation marker of erythroid cells. Okadaic acid caused decrease of the phosphotyrosine-containing proteins, presumably to maintain a balance between phosphorylation/dephosphorylation processes in the cells. Addition of 3-isobutyl-1-methyl-xanthine, an activator of phosphatases, caused a decrease or disappearance of almost all phosphotyrosine-containing proteins and, at the same time, prevented the erythroid differentiation of HD3 cells. Sodium orthovanadate, a specific inhibitor of phosphotyrosine phosphatase, increased the level of phosphotyrosine proteins and induced differentiation of HD3 cells. These results indicate that phosphorylation of cellular proteins is coupled with a reaction(s) which is responsible for triggering the differentiation of HD3 cells. The phosphorylation/dephosphorylation processes are associated with an early event(s) during the differentiation of HD3 cells and may not be connected to tyrosine residues.
在42摄氏度下用红细胞诱导剂（血红素和丁酸）处理HD3细胞后，含磷酸酪氨酸蛋白的图谱发生了改变。诱导后，含磷酸酪氨酸蛋白的总体水平增加。为了研究蛋白磷酸化在HD3细胞分化中的作用，用特异性抑制剂处理细胞。在冈田酸存在的情况下，细胞增殖被阻断，并伴随着血红蛋白合成的显著增加，血红蛋白是红细胞的一种分化标志物。冈田酸导致含磷酸酪氨酸蛋白减少，推测是为了维持细胞内磷酸化/去磷酸化过程之间的平衡。添加磷酸酶激活剂3-异丁基-1-甲基黄嘌呤，几乎使所有含磷酸酪氨酸蛋白减少或消失，同时阻止了HD3细胞的红细胞分化。正钒酸钠是磷酸酪氨酸磷酸酶的特异性抑制剂，它增加了磷酸酪氨酸蛋白的水平并诱导了HD3细胞的分化。这些结果表明，细胞蛋白的磷酸化与引发HD3细胞分化的一个或多个反应相关联。磷酸化/去磷酸化过程与HD3细胞分化早期的一个或多个事件相关，可能与酪氨酸残基无关。
