Differential role of nonmuscle myosin II isoforms during blebbing of MCF-7 cells

Abstract

One molecular cue that regulates cellular protrusions such as blebbing and lamellipodia in tumor cells has been less explored than other environmental factors. NM II-A induces blebbing and NM II-C1 induces lamellipodia in tumor cells. NM-II isoforms can change the protrusive activity of a tumor cell.

Ultrastructure of the actin cytoskeleton

“…A combination of bundles and meshworks in the cortex is consistent with functional contribution of both Arp2/3 complex and formins to cortex assembly [50,51,53**], although formins may play a dominant role for the assembly of the mitotic cortex [54] and stabilization of the rear surface in migrating cells [55]. Among different NMII paralogs, NMIIA has greater contribution to cortex stiffness and contractility than NMIIB or NMIIC, whereas NMIIB is more important for cortex stabilization [56].…”

“…Among different NMII paralogs, NMIIA has greater contribution to cortex stiffness and contractility than NMIIB or NMIIC, whereas NMIIB is more important for cortex stabilization [56]. …”

Common and Specific Functions of Nonmuscle Myosin II Paralogs in Cells

“…NMII filaments are not stationary within SFs but undergo constant turnover. When analyzed individually, NMIIB was found to exhibit slower dynamics than NMIIA [44, 45] and spend more time in the actin-bound state [46]. It is unlikely that different dynamics of NMIIA and NMIIB is driven by the differences in the bipolar filament assembly regulated by the shared MRLCs and by interaction between the conserved ACDs.…”

“…Conversely, NMIIB supports axon elongation in neurons [61] and lamellipodial protrusion in other cell types [53]. NMIIC also stimulates neurite outgrowth in neuroblastoma cells [55] and lamellipodial protrusion in epithelial cells [46].…”

“…Similar cortical networks also exist locally in the interphase cells and help to define the cell shape and mechanical properties of the cell surface. In the cell cortex, NMIIB and NMIIC promote cortex stability, which helps to reduce formation of surface blebs, whereas NMIIA supports cortex stiffness, contractility, and blebbing [46]. NMIIA also functions in erythrocytes, where it maintains the biconcave cell shape and regulates membrane tension by interacting with short actin filaments in the submembrane actin–spectrin network [80].…”