Integration of linear and dendritic actin nucleation in Nck-induced actin comets

Abstract

The role of the Nck adaptor protein in balancing linear versus branched actin nucleation in comet tails is evaluated. Nck recruits both linear and branched nucleation-promoting factors, both of which are necessary for the formation of actin comets. The findings highlight a novel role for Nck in pathogen-like actin motility.

Nck deficiency is associated with delayed breast carcinoma progression and reduced metastasis

“…, 2010 ). Because Nck integrates dendritic and linear actin nucleation ( Borinskaya et al. , 2016 ), we propose that Nck coordinates the molecular machineries directing the assembly of the complex actin network enabling the protrusive function of invadopodia.…”

Ultrastructure of the actin cytoskeleton

“…Formins, on the other hand, are thought to predominantly assemble actin bundles. However, accumulating data reveal a role of various formins in lamellipodial protrusion [12–16] and other branched networks [17,18], where formins can function as elongators and/or nucleators of actin filaments. Specifically, mDia2 can stimulate both elongation and nucleation of actin filaments in protrusions [16], FMNL2 seems to mostly promote elongation of Arp2/3-nucleated filaments, whereas FMNL3 and mDia1 appear to be largely implicated in nucleation [14,15].…”

Unique Organization of Actin Cytoskeleton in Magnocellular Vasopressin Neurons in Normal Conditions and in Response to Salt-Loading

“…Notably, although actin comet-like structures in MNCs do not resemble typical actin organization in non-neuronal cell types (Svitkina, 2018), such as stress fibers found in fibroblasts, epithelial and endothelial cells (Tojkander et al, 2012) or Arp2/3-dependent actin meshwork found in a variety of motile cells (Lehtimäki et al, 2016), they resemble filamentous actin structures propelling organelles such as endosomes and endocytic vesicles (Collins et al, 2011;Svitkina, 2018) and bacteria comet tails (Tilney and Portnoy, 1989;Cameron et al, 2000;Cameron et al, 2001;Svitkina, 2013). These structures are thought to be involved in organelle/vesicle trafficking and feature fast polymerizing actin filaments nucleated by Arp2/3 (Collins et al, 2011) or formins (Borinskaya et al, 2016). Future studies are needed to study dynamic properties of comet-like structures found in MNC somata and characterize their interacting partners, to determine if these comet-like filaments resemble axonal actin trails, organelle-propelling actin filaments, or represent a functionally distinct structure in MNCs that might be crucial for their unique physiology.…”