Growth factor-dependent AKT activation and cell migration requires the function of c-K(B)-Ras versus other cellular Ras isoforms
Growth factor-dependent AKT activation and cell migration requires the function of c-K(B)-Ras versus other cellular Ras isoforms
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DOI：
10.1074/jbc.m600668200
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发表时间：
2006-10-06
影响因子：
4.8
通讯作者：
Wolfman, Alan
中科院分区：
文献类型：
--
作者：
Liao, Jinhui;Planchon, Sarah M.;Wolfman, Alan
K-Ras阴性成纤维细胞在其MMP-2的稳态表达中有缺陷。这是通过依赖c-K（B）- Ras调节AKT活性的基础水平而发生的.在本报告中，我们扩展了这些研究，以证明在K-Ras表达缺失的情况下，PDGF-BB不能诱导显著的AKT活化，尽管在N-Ras阴性细胞中并非如此.这种表型与PDGF依赖性细胞迁移直接相关。所有独立永生化的K-Ras阴性细胞在加入PDGF后不能迁移。只有c-K（B）- Ras的异位表达，而不是c-K（A）- Ras或致癌的N-Ras，才能恢复PDGF依赖的AKT活化和细胞迁移.由于大多数Ras结合配偶体可以与所有Ras同种型相互作用，AKT的PDGF依赖性活化和增强的细胞迁移的特异性表明这些结果可能通过c-K（B）- Ras特异性结合配偶体调节.其他人已经发表了四种Ras异构体中，只有K（B）- Ras可以与钙调蛋白（CaM）形成稳定的复合物。沿着这些线索，我们提供了以下证据：1）PDGF的加入导致c-K（B）Ras和CaM之间复合物水平的增加，和2）严格依赖于c-K（B）- Ras的生物学结果（AKT活化和细胞迁移）被CaM拮抗剂阻断.不存在K（B）- Ras和存在CaM拮抗剂不影响ERK的PDGF依赖性活化.这是特定生物学结果、细胞迁移和单个Ras同种型c-K（B）- Ras活性之间联系的第一个例子。
K-Ras-negative fibroblasts are defective in their steady- state expression of MMP-2. This occurs through c- K( B)- Ras dependent regulation of basal levels of AKT activity. In this report, we have extended those studies to demonstrate that in the absence of K- Ras expression, PDGF- BB fails to induce significant AKT activation, although this was not the case in N- Ras- negative cells. This phenotype was directly linked to PDGF- dependent cell migration. All of the independently immortalized K-Ras-negative cells failed to migrate upon the addition of PDGF. Only ectopic expression of c- K( B)- Ras, not c- K( A)- Ras nor oncogenic N- Ras, could restore both PDGF- dependentAKTactivation and cell migration. Since most Ras binding partners can interact with all Ras isoforms, the specificity of PDGF- dependent activation of AKT and enhanced cell migration suggests that these outcomes are likely to be regulated through a c- K( B)- Ras- specific binding partner. Others have published that of the four Ras isoforms, only K( B)- Ras can form a stable complex with calmodulin ( CaM). Along those lines, we provide evidence that 1) PDGF addition results in increased levels of a complex between c- K( B)Ras and CaM and 2) the biological outcomes that are strictly dependent on c- K( B)- Ras ( AKT activation and cell migration) are blocked by CaM antagonists. The PDGF- dependent activation of ERK is unaffected by the absence of K( B)- Ras and presence of CaM antagonists. This is the first example of a linkage between a specific biological outcome, cell migration, and the activity of a single Ras isoform, c- K( B)- Ras.