Finch R A, Revankar G R, Chan P K
Department of Pharmacology, Baylor College of Medicine, Houston, Texas 77030.
J Biol Chem. 1993 Mar 15;268(8):5823-7.
Incubation of HeLa cells with the IMP dehydrogenase inhibitors: ribavirin (100 microM, 4 h), tiazofurin (100 microM, 4 h), selenazofurin (100 microM, 4 h), or mycophenolic acid (10 microM, 4 h) resulted in approximately 70% reduction in cellular GTP pools and shifting of nucleophosmin/B23 from nucleoli to nucleoplasm as detected by immunofluorescence (B23-translocation). Enzyme-linked immunosorbent assay and Western blot assay showed there is no loss or degradation of nucleophosmin/B23 protein during drug treatment. This translocation effect could be prevented by co-incubation with guanosine (100 microM) or reversed by addition of guanosine (100 microM) to the culture medium after B23-translocation had been induced by these inhibitors. Under these conditions of guanosine supplementation, cellular GTP pool concentrations were maintained at the control level. These results indicate that localization of nucleophosmin/B23 into the nucleolus is dependent on the cellular GTP level.
用肌苷单磷酸脱氢酶抑制剂（利巴韦林，100微摩尔，4小时；替唑呋林，100微摩尔，4小时；硒唑呋林，100微摩尔，4小时；或霉酚酸，10微摩尔，4小时）孵育HeLa细胞，导致细胞内GTP池减少约70%，并且通过免疫荧光检测发现核磷蛋白/B23从核仁转移至核质（B23易位）。酶联免疫吸附测定和蛋白质免疫印迹分析表明，在药物处理过程中核磷蛋白/B23蛋白没有损失或降解。这种易位效应可通过与鸟苷（100微摩尔）共同孵育来预防，或者在这些抑制剂诱导B23易位后，向培养基中添加鸟苷（100微摩尔）来逆转。在补充鸟苷的这些条件下，细胞内GTP池浓度维持在对照水平。这些结果表明，核磷蛋白/B23在核仁中的定位取决于细胞内GTP水平。
