Changes in actin organization during the cytotoxic process

Abstract

Changes in organization of F‐actin during the cytotoxic process between NK and K562 cells have been observed and studied using confpcal laser scanning microscopy and quantitative fluorescence microscopy. An increase in F‐actin content and orientation of F‐actin towards the target cell have been observed in, conjugated NK cells. The increase in F‐actin content probably reflects activation of the NK cell for the killing process. An increase in F‐actin content in the conjugated K562 cell, occurring simultaneously with the appearance of filamentous actin structures that often originated/ended at the contact place with the NK cell, was also observed. These changes were delayed compared to the increase in F‐actin content in the NK cell and were accompanied by increasing cytotoxic activity. This indicates that they were results of the interaction of the K562 cell with the activated NK cell. The possible role of target cell microfilaments in the cytotoxic process is addressed. © 1994 Wiley‐Liss, Inc.

Stepwise cytoskeletal polarization as a series of checkpoints in innate but not adaptive cytolytic killing

“…(iii) These data also demonstrate that more interface actin accumulation occurred in delayed killing interactions before the lytic hit than in nonkilling interactions, thus corroborating the differential interface maintenance described above. We corroborated the only occasional occurrence of actin accumulation at the NK cell-target cell interface by F-actin staining of fixed NK cell-target cell couples [data not shown; as also described earlier (24)(25)(26)], and in a much less extensive analysis of live cell actin accumulation in the anti-2B4 redirected lysis of P815 targets (data not shown). In summary, we found moderate actin accumulation at the NK cell-target cell interface, consistent with the often-tentative nature of the NK cell-target cell couples.…”

Differential expression and distribution of ezrin, radixin and moesin in human natural killer cells

“…The actin cytoskeleton exerts a key role in the early phases of the NK cell/target cell conjugation [2][3][4]6] and a straightforward polarization of the actin filaments occurs in NK cells before and during contact with the target cells [4]. Moreover, direct or indirect inhibition of cytoskeleton impairs NK cell activity [2,4,13].…”

“…g/ml, 40 min, at room temperature) and allowed to attach for 15 min. Then the cells were fixed (paraformaldehyde 3%, 30 min, +4°C), washed in quenching buffer (NH 4 Cl 50 mM, 10 min at room temperature) and permeabilized (TritonX-100 0.5%), 10 min at room temperature). For dual fluorescence CLSM analysis, cells were first stained with anti-ERM polyclonal Ab (30 min, +37°C) followed by donkey anti-goatAlexa594 (30 min, +37°C) and secondly stained with the anti-human perforin mAb (30 min, +37°C), followed by goat anti-mouse-Alexa488 (30 min, +37°C).…”

“…Particularly, actin filaments seem to drive both polarization of single NK cells and the formation of the immunological synapse between NK cells and the target cells [1][2][3][4]. NK cell polarity was intrinsically involved in conjugate formation [5][6].…”

Downregulation of Tumorogenicity and Changes in the Actin Cytoskeleton of Murine Hepatoma After Irradiation with Polychromatic Visible and IR Light

“…16 The structure of actin microfilaments is changed when interacting with natural killer (NK) cells that are effectors of the system of natural antitumor resistance and are capable of lysis of the large spectrum of tumor cell targets without their prior sensitization. Several studies 25,26 indicate that actin stress fibrils and ''disorganized'' actin localized in the cytoplasm can interfere with the cytotoxic process. Our data indicate that the total number of cells in the population with clearly pronounced stress fibrils are not altered, and that the number of cells with disorganized actin is the result of irradiation with VIS-IR light.…”