Regulators of Actin Dynamics in Gastrointestinal Tract Tumors

Figure 1

Simplified and schematic display of specialized cellular protrusions and key protein regulators involved in their formation and maintenance. (a) Filopodia consist of parallel actin filaments, which are formed by mDia2 upon Cdc42/protein kinase C signaling activity and then bundled by Fascin. (b) Rac/RhoA and/or Cdc42 signaling activates the WAVE complex, which, together with coregulators such as Abi1, stimulates Arp2/3-mediated actin branching and lamellipodial protrusion. (c) Invadopodia formation is mediated via N-WASP-mediated activation of Arp2/3 downstream Cdc42 signaling and might be further modulated by intracellular tyrosine kinase activity (Src, Abl). Furthermore, invadopodia secrete matrix metalloproteinases (MMPs) to degrade the extracellular matrix as a prerequisite for migration and invasion.

(a) Filopodia

(b) Lamellipodia

(c) Invadopodia