Sarmiento Corina, Wang Weigang, Dovas Athanassios, Yamaguchi Hideki, Sidani Mazen, El-Sibai Mirvat, Desmarais Vera, Holman Holly A, Kitchen Susan, Backer Jonathan M, Alberts Art, Condeelis John
Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA.
J Cell Biol. 2008 Mar 24;180(6):1245-60. doi: 10.1083/jcb.200708123.
We examined the role of the actin nucleation promoters neural Wiskott-Aldrich syndrome protein (N-WASP) and WAVE2 in cell protrusion in response to epidermal growth factor (EGF), a key regulator in carcinoma cell invasion. We found that WAVE2 knockdown (KD) suppresses lamellipod formation and increases filopod formation, whereas N-WASP KD has no effect. However, simultaneous KD of both proteins results in the formation of large jagged protrusions with lamellar properties and increased filopod formation. This suggests that another actin nucleation activity is at work in carcinoma cells in response to EGF. A mammalian Diaphanous-related formin, mDia1, localizes at the jagged protrusions in double KD cells. Constitutively active mDia1 recapitulated the phenotype, whereas inhibition of mDia1 blocked the formation of these protrusions. Increased RhoA activity, which stimulates mDia1 nucleation, was observed in the N-WASP/WAVE2 KD cells and was shown to be required for the N-WASP/WAVE2 KD phenotype. These data show that coordinate regulation between the WASP family and mDia proteins controls the balance between lamellar and lamellipodial protrusion activity.
我们研究了肌动蛋白成核促进因子神经型威斯科特-奥尔德里奇综合征蛋白（N-WASP）和WAVE2在细胞对表皮生长因子（EGF）作出反应而形成突起过程中的作用，EGF是癌细胞侵袭的关键调节因子。我们发现，敲低（KD）WAVE2会抑制片状伪足的形成并增加丝状伪足的形成，而敲低N-WASP则没有影响。然而，同时敲低这两种蛋白会导致形成具有片状特性的大的锯齿状突起，并增加丝状伪足的形成。这表明在癌细胞对EGF的反应中，另一种肌动蛋白成核活性在起作用。一种哺乳动物的Diaphanous相关的formin，mDia1，定位于双敲低细胞中的锯齿状突起处。组成型活性mDia1重现了该表型，而抑制mDia1则阻止了这些突起的形成。在N-WASP/WAVE2敲低细胞中观察到RhoA活性增加，其刺激mDia1成核，并且已证明它是N-WASP/WAVE2敲低表型所必需的。这些数据表明，WASP家族和mDia蛋白之间的协同调节控制着片状和片状伪足突起活性之间的平衡。
