Two N-myristoyltransferase isozymes play unique roles in protein myristoylation, proliferation, and apoptosis
Two N-myristoyltransferase isozymes play unique roles in protein myristoylation, proliferation, and apoptosis
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DOI：
10.1158/1541-7786.mcr-05-0037
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发表时间：
2005-08-01
影响因子：
5.2
通讯作者：
Smith, CD
中科院分区：
文献类型：
--
作者：
Ducker, CE;Upson, JJ;Smith, CD
N-肉豆蔻酰转移酶 (NMT) 将肉豆蔻酸添加到某些蛋白质的 NH2 末端，从而调节其定位和/或生物功能。这项研究利用 RNA 干扰，对人类细胞中两种 NMT 同工酶的功能进行了表征。针对每种同工酶设计了独特的小干扰 RNA (siRNA)，并显示可将 NMT1 或 NMT2 蛋白水平降低至少 90%。 NMT1 的消除抑制了与 c-Src 及其靶 FAK 激活丧失相关的细胞复制，以及通过 c-Raf/丝裂原激活蛋白激酶/细胞外信号调节激酶激酶/细胞外信号调节激酶途径的信号传导减少。末端脱氧核苷酸转移酶介导的 dUTP 缺口末端标记测定表明，任一 NMT 同工酶的消耗都会诱导细胞凋亡，其中 NMT2 的作用比 NMT1 大 2.5 倍。蛋白质印迹分析显示，NMT2 的缺失使 BCL 蛋白家族的表达转向细胞凋亡。最后，肿瘤内注射 NMT1 或 NMT1 和 NMT2 的 siRNA 抑制体内肿瘤生长，而使用 NMT2 的 siRNA 或阴性对照 siRNA 进行相同的治疗则不会。总体而言，数据表明 NMT1 和 NMT2 仅具有部分重叠的功能，并且 NMT1 对于肿瘤细胞增殖至关重要。
N-myristoyltransferases (NMT) add myristate to the NH2 termini of certain proteins, thereby regulating their localization and/or biological function. Using RNA interference, this study functionally characterizes the two NMT isozymes in human cells. Unique small interfering RNAs (siRNA) for each isozyme were designed and shown to decrease NMT1 or NMT2 protein levels by at least 90%. Ablation of NMT1 inhibited cell replication associated with a loss of activation of c-Src and its target FAK as well as reduction of signaling through the c-Raf/mitogen-activated protein kinase/extracellular signal-regulated kinase kinase/extracellular signal-regulated kinase pathway. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assays showed that depletion of either NMT isozyme induced apoptosis, with NMT2 having a 2.5-fold greater effect than NMT1. Western blot analyses revealed that loss of NMT2 shifted the expression of the BCL family of proteins toward apoptosis. Finally, intratumoral injection of siRNA for NMT1 or for both NMT1 and NMT2 inhibited tumor growth in vivo, whereas the same treatment with siRNA for NMT2 or negative control siRNA did not. Overall, the data indicate that NMT1 and NMT2 have only partially overlapping functions and that NMT1 is critical for tumor cell proliferation.