Min A, Hasuma T, Yano Y, Matsui-Yuasa I, Otani S
Department of Biochemistry, Osaka City University Medical School, Japan.
J Cell Physiol. 1995 Dec;165(3):615-23. doi: 10.1002/jcp.1041650320.
We examined the effect of inhibitors of tyrosine kinase and tyrosine phosphatase on DNA fragmentation, protein tyrosine phosphorylation, and polyamine metabolism in the murine T-cell line CTLL-2. When cells were exposed to herbimycin A, a specific inhibitor of tyrosine kinase (Uehara et al., 1989, Biochem. Biophys. Res. Commun., 163:803-809), in the presence of interleukin 2 (IL-2), DNA was degraded into oligonucleosomal fragments in a dose-dependent fashion. Genistein, another inhibitor of tyrosine kinase (Akiyama et al., 1987, J. Biol. Chem., 262:5592-5596), had similar effects. Exposure of CTLL-2 cells to vanadate, a tyrosine phosphatase inhibitor, blocked with the DNA fragmentation induced by herbimycin A. Tyrosine phosphorylation of 55 Kd protein was inhibited by herbimycin A, and the inhibition was reduced by vanadate. Ornithine decarboxylase (ODC) activity decreased rapidly after herbimycin A was added to CTLL-2 cell cultures, while vanadate increased ODC activity. The exogenous addition of putrescine or spermine, but not that of spermidine, attenuated herbimycin A-induced DNA fragmentation. These findings suggest that phosphorylation of tyrosine residues of 55 Kd protein prevents DNA fragmentation and that polyamines are involved in regulation of apoptosis.
我们研究了酪氨酸激酶和酪氨酸磷酸酶抑制剂对小鼠T细胞系CTLL-2中DNA片段化、蛋白质酪氨酸磷酸化和多胺代谢的影响。当细胞在白细胞介素2（IL-2）存在的情况下暴露于酪氨酸激酶的特异性抑制剂赫比霉素A（Uehara等人，1989年，《生物化学与生物物理研究通讯》，163:803 - 809）时，DNA以剂量依赖的方式降解为寡核小体片段。染料木黄酮，另一种酪氨酸激酶抑制剂（Akiyama等人，1987年，《生物化学杂志》，262:5592 - 5596），有类似的作用。将CTLL-2细胞暴露于酪氨酸磷酸酶抑制剂钒酸盐，可阻断赫比霉素A诱导的DNA片段化。赫比霉素A抑制55 Kd蛋白的酪氨酸磷酸化，而钒酸盐可减轻这种抑制作用。在CTLL-2细胞培养物中加入赫比霉素A后，鸟氨酸脱羧酶（ODC）活性迅速下降，而钒酸盐则增加ODC活性。外源添加腐胺或精胺，但不是亚精胺，可减弱赫比霉素A诱导的DNA片段化。这些发现表明，55 Kd蛋白酪氨酸残基的磷酸化可防止DNA片段化，并且多胺参与细胞凋亡的调控。
