Rapamycin resistance in ataxia-telangiectasia.
Rapamycin resistance in ataxia-telangiectasia.
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发表时间：
1996-09
期刊：
影响因子：
8
通讯作者：
H. Beamish;R. Williams;Philip C. Chen;K. Khanna;K. Hobson;D. Watters;Yosef Shiloh;M. Lavin
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文献类型：
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作者：
H. Beamish;R. Williams;Philip C. Chen;K. Khanna;K. Hobson;D. Watters;Yosef Shiloh;M. Lavin
最近已经描述了在人类遗传疾病共济失调-毛细血管扩张症（A-T）中突变的基因（Savitsky等人，1995 a），并且已经报道了该基因ATM的完整编码序列（Savitsky等人，1995年b）。衍生的氨基酸序列与含有磷脂酰肌醇3-激酶（PI 3-激酶）结构域的几种蛋白质（包括酵母TOR蛋白和人蛋白FRAP）具有显著的同源性。由于TOR和FRAP蛋白是免疫抑制药物雷帕霉素的靶点，我们研究了这种化合物对A-T细胞的影响。我们在这里报告，3 A-T细胞系比对照细胞更耐雷帕霉素的生长抑制作用，但更敏感的PI 3激酶抑制剂渥曼青霉素。正如预期的，雷帕霉素（1 nM）抑制了对照细胞从G1期退出的速率，但未能干扰A-T细胞的进展。雷帕霉素处理后细胞周期进程的这种差异反映在核糖体S6蛋白激酶（p70 S6 k）中，通过SDS-PAGE上的向下迁移率移动和活性抑制。此外，G1期细胞周期蛋白依赖性激酶，细胞周期蛋白E-cdk 2，迅速抑制在对照细胞处理后，而在A-T细胞中，它需要相当长的时间来观察抑制。没有证据表明GST-FKBP 12融合蛋白在雷帕霉素存在下在任一细胞类型中特异性沉淀ATM蛋白。这些结果表明，ATM蛋白不是雷帕霉素的直接靶标，但其功能丧失使细胞对该化合物更具抗性。
The gene mutated in the human genetic disorder ataxia-telangiectasia (A-T) has been described recently (Savitsky et al., 1995a) and the complete coding sequence of this gene, ATM, has been reported (Savitsky et al., 1995b). The derived amino acid sequence demonstrates significant homologies to several proteins containing a phosphatidylinositol 3-kinase (PI3-kinase) domain, including the yeast TOR proteins and the human protein FRAP. Since the TOR and FRAP proteins are targets for the immunosuppressive drug rapamycin, we have investigated the effects of this compound on A-T cells. We report here that 3 A-T cell lines are more resistant than control cells to rapamycin's growth inhibiting effects but were more sensitive to the PI3-kinase inhibitor wortmannin. As expected rapamycin (1 nM) inhibited the rate of exit of control cells from G1 phase but failed to perturb the progression of A-T cells. This difference in cell cycle progress after rapamycin treatment is reflected in ribosomal S6 protein kinase (p70S6k) by both a downward mobility shift on SDS-PAGE and inhibition of activity. Furthermore, the G1 phase cyclin-dependent kinase, cyclin E-cdk2, was rapidly inhibited in control cells post-treatment, whereas in A-T cells it took considerably longer to observe inhibition. There was no evidence that a GST-FKBP12 fusion protein specifically precipitated the ATM protein in the presence of rapamycin in either cell type. These results demonstrate that the ATM protein is not a direct target for rapamycin but its functional loss renders cells more resistant to this compound.