Regulation of polymorphonuclear leukocyte membrane fluidity: effect of cytoskeletal modification

Abstract

We previously demonstrated that the f-actin cytoskeleton modulates oxygen radical production associated with polymorphonuclear leukocyte (PMN) oxidative burst activity. Given the close association of the actin and microtubule cytoskeletons with the plasma membrane and the transmembrane location of the PMN NADPH oxidase, it is likely cytoskeletal change may affect PMN membrane responses, such as cellular anisotropy. Changes in PMN membrane fluidity were therefore examined after PMN activation by the chemoattractant N-formyl-1-methionyl-1-leucyl-1-phenylalanine (fMLP) in the presence or absence of phalloidin or cytochalasin B (CB), agents that stabilize and disrupt f-actin, or taxol and vincristine, which stabilize and disrupt microtubules, respectively. Phalloidin and taxol treatment of PMN significantly decreased whereas CB and vincristine significantly increased membrane fluidity. Activation of PMN by fMLP (10(-6) M) resulted in a significant increase in membrane fluidity that was attenuated by PMN pretreatment with phalloidin or taxol. CB and vincristine pretreatment of PMN did not alter the fMLP response. These data suggest that stabilization of the f-actin or microtubule cytoskeleton may prevent increases in cellular membrane fluidity associated with PMN activation.

Rigidity of Circulating Lymphocytes Is Primarily Conferred by Vimentin Intermediate Filaments

“…This conclusion is based in part on findings that microtubule disruption decreases leukocyte stiffness (6,9,25) and increases lymphocyte penetration into confined three-dimensional matrices (4). However, due to secondary effects of microtubule-disrupting agents on leukocyte actin microfilaments, cell motility (26), and IFs (27), it is unclear whether microtubules directly contribute to the rigidity of spherical lymphocytes.…”

Evidence that actin disassembly is a requirement for matrix metalloproteinase secretion by sinusoidal endothelial cells during cold preservation in the rat

“…20 Two milligrams per milliliter of stock solution of phalloidin (Sigma Chemical Co.) was prepared in ethanol and stored at Ϫ20°C until use. 21,22 To disrupt F-actin, SECs were treated with cytochalasin B at a final concentration of 2 µg/mL in EGM for 8 hours. To stabilize F-actin, SECs were incubated in the presence of 10 µmol/L phalloidin in EGM overnight at 37°C.…”

“…This method has previously been shown to be effective in obtaining entry of phalloidin into living cells. 21,22 Studies by Barak et al 23 and Korthuis et al 24 which have examined entry of phalloidin into living cells suggest that it occurs by pinocytosis. Controls were not treated either with cytochalasin B or phalloidin.…”

A Direct Synergistic Effect of Immunotherapy and Chemotherapy as a New Paradigm in Treatment of Breast Cancer

“…Chemotherapy causes disruption of tumor stroma that allows better penetration of antigen-specific T cells. Most importantly chemotherapy may affect the fluidity of the tumor cell membrane (15,16), which may result in increased permeability of the cells to GrzB. In this situation a small number of activated CTLs able to release GrzB can kill neighboring tumor cells without cell-cell contact.…”

“…Median survival for patients with metastatic breast cancer is 18-24 months. Among patients treated with systemic chemotherapy 16.6% achieved complete responses and only 3.1% remained in complete remission for more than 5 years (1). Patients with locally advanced breast cancer (LABC) have a poor prognosis when treated with surgery and radiotherapy.…”