How do filopodia pull on a substrate? Although a reterograde motion of actin filaments is intrinsic in the formation of filopodia, the forces generated by actin treadmilling are too weak to facilitate the “pulling” mechanism required for rigidity sensing and other mechanosensing processes. This [...]
What causes filopodia retraction and collapse? Binding of filopodia to certain ligands or substratum may hinder filament assembly, thereby leading to changes that promote retraction, collapse or growth cone turning [1][2]. For example, substrate contacts with a repulsive signal on one side of a [...]
What are lamellipodia and lamella? The lamellipodia and lamella are plate-like extensions of the cell that play crucial roles in both cell motility and migration, and mechanosensing. These structures form and function over distinct steps. Lamellipodia are thin, sheet-like membrane protrusions found at the [...]
How does nucleation of actin initiate lamellipodia formation? In the first phase of lamellipodia formation, actin filament polymerization produces a protrusive force on the cell membrane that promotes the spreading out and enlargement of the lamellipodia. In polarized, migrating cells this is known as [...]
What mechanisms drive extension, pause and stasis of the lamellipodia? Extension of the newly formed actin filament branches occurs at the interface between the leading edge and the existing actin filament network [1] and is maintained by mechanisms such as actin treadmilling. As reviewed [...]
How do focal adhesions act as molecular clutches in lamellipodia? Once formed, focal adhesions essentially act as “molecular clutches”, promoting protrusion at the leading edge whilst suppressing membrane contraction (reviewed in [1] [2][3]). Adhesions aid forward movement by regulating the forces produced by actin [...]
How does force generation within lamellipodia facilitate cell translocation? Interactions between actin filament networks and the focal adhesions to which they are linked results in the generation of forces. These forces may be exerted internally through actin bundle tension and filament network dynamics or [...]
What mechanisms drive retraction of the trailing edge? Protrusion at the front and retraction at the rear are key force-generating processes at the cell periphery that culminate in the translocation of the cell. For forces to be translated into a net forward gain in [...]
What are invadopodia? Invadopodia are actin-rich structures that are present at the basal surfaces of cells that are capable of crossing extracellular barriers, such as cancer cells. The primary function of invadopodia appears to be the focal degradation of the extracellular matrix (ECM) through [...]
What is the role of the lamellipodia in mechanosensing and cell motility? During cell migration, and in the absence of filopodia, lamellipodia detect the stiffness of the surrounding ECM in a process called rigidity sensing. Several models have been proposed that describe this process. [...]
What steps are involved in Lamellipodia assembly? The lamellipodia is a distinct region of the cell that facilitates cell motility and various mechanosensing mechanisms. Lamellipodium assembly can be described in a series of defined steps, many of which involve processes related to cytoskeletal dynamics, [...]
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 [...]
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One of four Research Centres of Excellence at NUS, MBI is working to identify, measure and describe how the forces for motility and morphogenesis are expressed at the molecular, cellular and tissue level.