Direct Binding of the EGF-like Domain of Neuregulin-1 to Integrins (αvβ3 and α6β4) Is Involved in Neuregulin-1/ErbB Signaling
Direct Binding of the EGF-like Domain of Neuregulin-1 to Integrins (αvβ3 and α6β4) Is Involved in Neuregulin-1/ErbB Signaling
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DOI：
10.1074/jbc.m110.113878
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发表时间：
2010-10-08
影响因子：
4.8
通讯作者：
Takada, Yoshikazu
中科院分区：
文献类型：
--
作者：
Ieguchi, Katsuaki;Fujita, Masaaki;Takada, Yoshikazu
整合素-生长因子受体的串扰在生长因子信号传导中起作用，但具体情况尚不清楚。在目前的模型中，整合素和生长因子受体独立地结合到它们的配体（分别是细胞外基质和生长因子）。我们发现，神经调节蛋白1（NRG 1），无论是作为一个孤立的EGF样结构域或作为一个天然的多结构域的形式，结合整合素α v β 3（具有1.36 × 10（-7）M的K-D）和α 6 β 4。对接模拟预测EGF样结构域180、184和186位的三个赖氨酸残基参与整合素结合。将这些残基单独或组合突变为Glu显著抑制整合素结合和ErbB 3磷酸化。在MCF-7和T47 D人乳腺癌细胞中，将所有三个Lys残基突变为Glu（3 KE突变）并不影响NRG 1与ErbB 3结合的能力，但显著降低了NRG 1诱导ErbB 3磷酸化以及AKT和Erk 1/2激活的能力。这表明整合素与NRG 1的直接结合对于NRG 1/ErbB信号传导至关重要。值得注意的是，用WT NRG 1刺激细胞诱导ErbB 3与α 6 β 4和α v β 3的共沉淀的程度低得多。这表明WT NRG 1诱导整联蛋白-NRG 1-ErbB 3三元复合物形成。相比之下，3 KE突变体在诱导三元复合物形成方面比WT NRG 1有效得多，这表明该过程依赖于NRG 1结合整联蛋白的能力。这些结果表明，直接的NRG 1-整联蛋白相互作用介导的整联蛋白-ErbB的串扰和α 6 β 4在NRG-ErbB信号在这些癌细胞中发挥了重要作用。
Integrin-growth factor receptor cross-talk plays a role in growth factor signaling, but the specifics are unclear. In a current model, integrins and growth factor receptors independently bind to their ligands (extracellular matrix and growth factors, respectively). We discovered that neuregulin-1 (NRG1), either as an isolated EGF-like domain or as a native multi-domain form, binds to integrins alpha v beta 3 (with a K-D of 1.36 x 10(-7) M) and alpha 6 beta 4. Docking simulation predicted that three Lys residues at positions 180, 184, and 186 of the EGF-like domain are involved in integrin binding. Mutating these residues to Glu individually or in combination markedly suppressed integrin binding and ErbB3 phosphorylation. Mutating all three Lys residues to Glu (the 3KE mutation) did not affect the ability of NRG1 to bind to ErbB3 but markedly reduced the ability of NRG1 to induce ErbB3 phosphorylation and AKT and Erk1/2 activation in MCF-7 and T47D human breast cancer cells. This suggests that direct integrin binding to NRG1 is critical for NRG1/ErbB signaling. Notably, stimulation of cells with WT NRG1 induced co-precipitation of ErbB3 with alpha 6 beta 4 and with alpha v beta 3 to a much lower extent. This suggests that WT NRG1 induces integrin-NRG1-ErbB3 ternary complex formation. In contrast, the 3KE mutant was much less effective in inducing ternary complex formation than WT NRG1, suggesting that this process depends on the ability of NRG1 to bind to integrins. These results suggest that direct NRG1-integrin interaction mediates integrin-ErbB cross-talk and that alpha 6 beta 4 plays a major role in NRG-ErbB signaling in these cancer cells.