What is the function of stress fibers? Stress fibers are contractile in nature. By exerting and maintaining tension on the underlying substratum, they form a key element of the mechanotransduction apparatus that links the cell interior and exterior. The organization of stress fibers resembles [...]

What mechanisms drive invadopodia extension? Following initiation by an appropriate signal, the actin cytoskeleton is reorganized to facilitate invadopodia formation. Although several kinases and GTPases are known to influence the transduction of extracellular signaling events leading to F-actin nucleation, there is currently no clear [...]

How do invadopodia degrade the extracellular matrix? The main function attributed to invadopodia is that of extracellular matrix (ECM) degradation, facilitated by the secretion of proteases. Maintenance of this process requires the delivery of new proteases from the Golgi, which is conveniently positioned in [...]

What is the first step in invadopodia assembly? Initiation of invadopdia formation is highly complex, being influenced by various signalling cascades and phosphorylation events that occur following detection of a stimulant. For example, activation of the epidermal growth factor (EGF) receptor by EGF has [...]

What are podosomes? Podosomes are actin-rich, adhesive structures that are present at the ventral surface of cells of the monocytic myeloid lineage, stimulated endothelial cells [1] and cultured Src-transformed cancer cells. These structures are not limited to the cell periphery, but do exhibit a [...]

What are the functions of podosomes? Both focal adhesions and podosomes are intimately involved in cell motility, with podosomes specifically implicated in cell invasion. Invasiveness is achieved through the secretion of matrix metalloproteinases (MMPs) from the core of podosomes, which degrade the extracellular matrix [...]

What is the first step in podosome assembly? Podosome initiation and assembly is highly regulated, both spatially and temporally. Dendritic cells best exemplify the temporal regulation of podosome formation. Following activation by an antigen or inflammatory cytokine, immature dendritic cells have a small window [...]

What mechanisms drive cytoskeleton extension within podosomes? Interactions between the extracellular matrix (ECM) and cell surface integrins leads to podosome formation. The initiating signal is transduced through mechanosensing integrins to the cytoskeleton, upon which the actin network undergoes significant re-organization to promote formation of [...]

What are the steps in dorsal stress fiber formation? Dorsal stress fibers in motile cells are formed from actin filament bundles that are initiated and extended from cell-substrate adhesions at the leading edge (aka focal complexes [FXs]) (reviewed in [1]). Similar to graded polarity [...]

What are the steps in the formation of transverse arcs? In general, initiation of stress fiber formation is modulated by signaling cascades involving RhoA small GTPase [1] (reviewed in [2]). Most G-actin polymerization is driven by the actin polymerizing machinery at the barbed end [...]

What are the steps in ventral stress fiber formation? Recent data suggests that ventral stress fibers are created by reorganizing pre-existing dorsal stress fibers and transverse arcs [1].Other contrasting models for the formation of ventral stress fibers not covered in this resource include annealing [...]

How is stress fiber assembly regulated? Tension-dependent actin polymerization and assembly of stress fibers is influenced by many factors (reviewed in [1][2]), including differences in substrate composition [3], rigidity [4][5][6] (reviewed in [7]), cell membrane phospholipids [8], external force (reviewed in [9]), as well [...]