Actin Cytoskeleton Dynamics
Rho GTPase-regulated actin polymerization driving cell shape and motility.
Overview
The actin cytoskeleton is dynamically regulated by Rho family GTPases: Rac1 drives lamellipodia (branched actin via Arp2/3), Cdc42 drives filopodia (linear actin via formins), and RhoA drives stress fibers and focal adhesions (via ROCK and mDia). Actin monomers (G-actin) polymerize into filaments (F-actin) in an ATP-dependent process. Cofilin severs and depolymerizes old filaments, profilin promotes polymerization, and capping proteins regulate filament length.
Cellular Location
Cell cortex, leading edge, focal adhesions
Clinical Significance
Essential for cell migration, wound healing, immune cell function, and neuronal growth cones; hijacked by pathogens (Listeria, Shigella); cancer metastasis requires actin-driven invasion.
Key Molecules
Key Enzymes
Related Pathways
G Protein-Coupled Receptor (GPCR) Signaling
Seven-transmembrane receptors activating heterotrimeric G proteins.
PI3K/AKT/mTOR Pathway
Regulates cell survival, growth, and metabolism via phosphoinositide signaling.
Epithelial-Mesenchymal Transition (EMT)
Cellular program converting epithelial cells to motile mesenchymal phenotype.