Cortical Flow in Animal Cells

Abstract

A concerted flow of actin filaments associated with the inner face of the plasma membrane may provide the basis for many animal cell movements. The flow is driven by gradients of tension in the cell cortex, which pull cortical components from regions of relaxation to regions of contraction. In some cases cortical components return through the cytoplasm to establish a continuous cycle. This cortically located motor may drive cell locomotion, growth cone migration, the capping of antigens on a lymphocyte surface, and cytokinesis.

Cell-sized liposomes reveal how actomyosin cortical tension drives shape change

“…A crucial cell module that drives cellular shape changes is the actomyosin cortex beneath the cell membrane, which produces contractile forces that squeeze the cell forward during migration or constrict it during division. The cell cortex is a thin actin network of thickness ∼0.2 μm (3), which is tightly attached to the plasma membrane (4,5). On the molecular scale, contractile forces are generated by myosin II motor proteins, associated into bipolar filaments (6), which use adenosine 5′-triphosphate (ATP) to exert pulling forces on actin filaments.…”

Fluorescence and Electron Microscopic Localization of F-actin in the Ependymocytes

“…it, the association between F-actin and intermediate filaments in the apical cytoplasm is suggested to play an important role in maintaining the integrity of epithelial cells (Bray and White 1988;Hollenbeck et al 1989).…”

“…The cytoskeleton in living cells is composed of three separate filamentous networks: microfilaments, micro- tubules, and intermediate filaments (Bray and White 1988;Hollenbeck et al 1989). Fluorescence microscopic studies showed that F-actin shares a similar localization and arrangement in the central canal and choroid plexus in the rat.…”

Actions of cytochalasins on the organization of actin filaments and microtubules in a neuronal growth cone.

“…A local actin cycle is necessary to support such a flow model; the retrograde flow of cortical F-actin networks being balanced by an approximately equal anterograde diffusion or other flux of actin monomers. An actin cycle of this type has recently been proposed as a general concept for understanding cell surface motility and locomotion in animal cells (9).…”