IRSp53/Eps8 complex is important for positive regulation of Rac and cancer cell motility/invasiveness
IRSp53/Eps8 complex is important for positive regulation of Rac and cancer cell motility/invasiveness
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DOI：
10.1158/0008-5472.can-04-0327
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发表时间：
2004-08-01
期刊：
影响因子：
11.2
通讯作者：
Miki, H
中科院分区：
文献类型：
--
作者：
Funato, Y;Terabayashi, T;Miki, H
IRSp53被认为是连接rho家族小gtpase（如Rac）与肌动蛋白细胞骨架重组的衔接蛋白。在这里，我们寻找IRSp53 SH3结构域的其他结合伙伴，并确定Eps8是成纤维细胞和各种癌细胞系的主要结合蛋白。Eps8已被证明与Abi-1和Sos-1形成rac特异性鸟嘌呤核苷酸交换因子复合物，这似乎是由致癌Ras诱导的褶皱形成所必需的。我们在体内证实了IRSp53/Eps8复合物的形成，以及Eps8 nh2末端脯氨酸丰富序列与IRSp53 SH3结构域之间的直接关联。该复合物通过增强Eps8/Abi-1/Sos-1 Rac-鸟嘌呤核苷酸交换因子复合物的形成协同激活Rac，从而介导Rac活性的正向调节。此外，荧光共振能量转移分析发现IRSp53/Eps8复合物的形成发生在运动细胞的前缘，抑制复合物的形成抑制HT1080纤维肉瘤细胞的运动和侵袭性。这些发现暗示了IRSp53/Eps8复合物在恶性肿瘤细胞的Rac激活和转移行为中的重要性。
IRSp53 has been characterized as an adaptor protein that links Rho-family small GTPases, such as Rac, to reorganization of the actin cytoskeleton. Here, we search for other binding partners for the IRSp53 SH3 domain and identify Eps8 as the major binding protein in fibroblasts and various cancer cell lines. Eps8 has been shown to form a Rac-specific guanine nucleotide exchange factor complex with Abi-1 and Sos-1, which seems essential for ruffling formation induced by oncogenic Ras. We confirm the IRSp53/Eps8 complex formation in vivo and the direct association between Eps8 NH2-terminal proline-rich sequence and IRSp53 SH3 domain. This complex synergistically activates Rac by reinforcing the formation of the Eps8/Abi-1/Sos-1 Rac-guanine nucleotide exchange factor complex, which mediates positive regulation of Rac activity. In addition, IRSp53/Eps8 complex formation as determined by fluorescent resonance energy transfer analysis, occurs at the leading edge of motile cells, and the motility and invasiveness of HT1080 fibrosarcoma cells are suppressed by inhibiting complex formation. These findings implicate the importance of the IRSp53/Eps8 complex in Rac activation and metastatic behavior of the malignant tumor cells.