Tumor metastasis suppressor nm23H1 regulates Rac1 GTPase by interaction with Tiam1
Tumor metastasis suppressor nm23H1 regulates Rac1 GTPase by interaction with Tiam1
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DOI：
10.1073/pnas.071411598
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发表时间：
2001-04-10
影响因子：
11.1
通讯作者：
Sugimura, H
中科院分区：
文献类型：
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作者：
Otsuki, Y;Tanaka, M;Sugimura, H
假定的肿瘤转移抑制因子 nm23H1 最初是通过消减克隆在小鼠黑色素瘤中发现的。它显示核苷二磷酸激酶活性并调节细胞事件，包括生长和发育。最近，据报道 nm23H1 也可作为 Ras 相关 GTPase Rad 的 GTPase 激活蛋白。我们试图确定 nm23H1 是否也调节 Rho 家族 GTPases。尽管我们无法检测 nm23H1 和 Rho 家族 GTPases 之间的直接关联，但通过与表达外源 Tiam1 的细胞和天然组织提取物中的氨基末端区域相互作用，nm23H1 被证明与 Rad 特异性核苷酸交换因子 Tiam1 相关。 nm23H1 的过度表达抑制 Tiam1 诱导的 GTP 结合 Rad 的产生和 c-Jun 激酶的激活。另一方面，强制过度表达野生型而非nm23H1的激酶失活突变体，通过其核苷二磷酸激酶活性将Rad、Cdc42和RhoA的CDP结合场在体外转化为其GTP结合形式，但单独的nm23H1显然不能在体内产生这些GTP酶的GTP结合形式。这些结果表明 nm23H1 负向调节 Tiam1 并抑制体内 Rad 激活。此外，过度表达 nm23H1 可以减少 Rat1 成纤维细胞粘附刺激的膜皱褶。基于这些观察，我们得出结论，我们已经确定 nm23H1 作为 Rac1 调节剂的功能，并且它可能与 nm23H1 作为肿瘤转移抑制因子的作用有关。
The putative tumor metastasis suppressor nm23H1 was originally identified in murine melanomas by subtraction cloning. It displays nucleoside diphosphate kinase activity and regulates cellular events, including growth and development. Recently nm23H1 has been reported to also act as a GTPase-activating protein of the Ras-related GTPase Rad. We attempted to determine whether nm23H1 also regulates Rho-family GTPases. Although we were unable to detect a direct association between nm23H1 and Rho-family GTPases, nm23H1 was shown to be associated with a Rad-specific nucleotide exchange factor, Tiam1, by interaction with its amino-terminal region in extracts from the cells expressing exogenous Tiam1 and from native tissue. Overexpression of nm23H1 inhibited the Tiam1-induced production of GTP-bound Rad and activation of c-Jun kinase. On the other hand, forced overexpression of the wild type, but not the kinase-inactivated mutant of nm23H1, converted the CDP bound farms of Rad, Cdc42, and RhoA to their GTP-bound forms in vitro by its nucleoside diphosphate kinase activity, but nm23H1 alone apparently did not produce the GTP-bound form of these GTPases in vivo. These results suggest that nm23H1 negatively regulates Tiam1 and inhibits Rad activation in vivo. Moreover, adhesion-stimulated membrane ruffles of Rat1 fibroblasts were reduced by overexpression of nm23H1. Based on these observations, we concluded that we had identified a function of nm23H1 as a regulator of Rac1 and that it may be related to the effect of nm23H1 as a tumor metastasis suppressor.