The function of intermediate filaments in cell shape and cytoskeletal integrity.

Abstract

Abstract. This study describes the development and use of a specific method for disassembling intermediate filament (IF) networks in living cells. It takes advantage of the disruptive effects of mimetic peptides derived from the amino acid sequence of the helix initiation 1A domain of IF protein chains. The results demonstrate that at 1:1 molar ratios, these peptides disassemble vimentin IF into small oligomeric complexes and monomers within 30 min at room temperature in vitro. Upon microinjection into cultured fibroblasts, these same peptides induce the rapid disassembly of IF networks. The disassembly process is accompanied by a dramatic alteration in cell shape and the destabilization of microtubule and actin-stress fiber networks. These changes in cell shape and IF assembly states are reversible. The results are discussed with respect to the roles of IF in cell shape and the maintenance of the integrity and mechanical properties of the cytoplasm, as well as the stability of the other major cytoskeletal systems.

Rigidity of Circulating Lymphocytes Is Primarily Conferred by Vimentin Intermediate Filaments

“…2c). Alternative methods for disrupting IFs, including acrylamide exposure (19) and microinjection of vimentindisruptive mimetic peptides (20), were ineffective, toxic, or impractical for use with spherical PBT. Pretreatment with the microtubule-stabilizing agent taxol prevented microtubule depolymerization during cold plus calyculin A exposure.…”

“…The interactions of IFs with other cellular components and their distribution in the cytoplasm may also contribute to their role as structural supports (20,36). IFs interact with the plasma membrane, the nucleus, and other cytoskeletal elements (37), and these interactions may regulate the position of the nucleus and mediate the transmission of external forces throughout the cell (5,20,36).…”

Feeder-Free Monolayer Cultures of Human Embryonic Stem Cells Express an Epithelial Plasma Membrane Protein Profile

“…However, vimentin is not specific for mesenchymal cells but is also found in migrating epithelial cells [26] and cells experiencing mechanical stress [27]. Since vimentin levels were substantially reduced when feeder-free hESCs were maintained on Hydrogel, it is more likely that vimentin expression results from growth on a rigid substrate rather than the initiation of differentiation due to the absence of feeder cells.…”

Fine structure of Eimer's organ in the coast mole (Scapanus orarius)

“…Tonofibrils serve as a structural support network that imparts rigidity to the cell and provides resilience to mechanical stresses (Janmey et al, 1991;Goldman et al, 1996;Yoon et al, 2001). The central column cells of the Eimer's organ are heavily invested with tonofibril bundles (Figs.…”