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 stress fibers? Stress fibers are higher order cytoskeletal structures composed of cross-linked actin filament bundles, and in many cases, myosin motor proteins, that span a length of 1-2 micrometers [1]. At least 4 types of stress fibers have been identified in mammalian [...]

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 axon guidance and the growth cone? Axon guidance is an important step in neural development. It allows growing axons to reach specific destinations and ultimately form the complex neuronal networks throughout the body. Although many aspects of this mechanism remains unclear, it [...]

What are Motor Proteins? Motor proteins, such as myosins and kinesins, move along cytoskeletal filaments via a force-dependent mechanism that is driven by the hydrolysis of ATP molecules (reviewed in [1]). Nucleotide hydrolysis and controlled inorganic phosphate release by motor proteins causes restructuring of [...]

How do motor proteins transport cargo along the cytoskeleton? Along with providing structural support to the cell, and transmitting force signals, cytoskeletal filaments also provide cells with a network of ‘tracks’ that can be followed by specific proteins for the directed delivery of vesicles [...]

What is Myosin? An Introduction to the Myosin Superfamily of Proteins Myosin I has unique tail domain(s) relative to other myosin members which allows myosin I to bind to membrane lipids or to more than one actin filament at a time (see panel ‘A’ [...]

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 [...]