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Mol Biol Cell April 1, 2008; 19 (4): 1561-74.

Arp2/3 complex is important for filopodia formation, growth cone motility, and neuritogenesis in neuronal cells.

Korobova F , Svitkina T .

A role of Arp2/3 complex in lamellipodia is well established, whereas its roles in filopodia formation remain obscure. We addressed this question in neuronal cells, in which motility is heavily based on filopodia, and we found that Arp2/3 complex is involved in generation of both lamellipodia and filopodia in growth cones, and in neuritogenesis, the processes thought to occur largely in Arp2/3 complex-independent manner. Depletion of Arp2/3 complex in primary neurons and neuroblastoma cells by small interfering RNA significantly decreased the F-actin contents and inhibited lamellipodial protrusion and retrograde flow in growth cones, but also initiation and dynamics of filopodia. Using electron microscopy, immunochemistry, and gene expression, we demonstrated the presence of the Arp2/3 complex-dependent dendritic network of actin filaments in growth cones, and we showed that individual actin filaments in filopodia originated at Arp2/3 complex-dependent branch points in lamellipodia, thus providing a mechanistic explanation of Arp2/3 complex functions during filopodia formation. Additionally, Arp2/3 complex depletion led to formation of multiple neurites, erratic pattern of neurite extension, and excessive formation of stress fibers and focal adhesions. Consistent with this phenotype, RhoA activity was increased in Arp2/3 complex-depleted cells, indicating that besides nucleating actin filaments, Arp2/3 complex may influence cell motility by altering Rho GTPase signaling.

PubMed ID: 18256280
PMC ID: PMC2291425
Article link: Mol Biol Cell
Grant support: [+]

Species referenced: Xenopus
Genes referenced: aagab actl6a actr2 actr3 aicda rho.2 rhoa
GO keywords: Arp2/3 protein complex [+]

Article Images: [+] show captions
References [+] :
Adams, Roles of fascin in cell adhesion and motility. 2004, Pubmed