Reorganization of the actin cytoskeleton during the formation of neutrophil extracellular traps (NETs)
We analyzed actin cytoskeleton alterations during NET extrusion by neutrophil-like dHL-60 cells and human neutrophils in the absence of DNase1 containing serum to avoid chromatin degradation and microfilament disassembly. NET-formation by dHL-60 cells and neutrophils was induced by Ionomycin or phor...
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Veröffentlicht in: | European journal of cell biology 2024-06, Vol.103 (2), p.151407, Article 151407 |
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Zusammenfassung: | We analyzed actin cytoskeleton alterations during NET extrusion by neutrophil-like dHL-60 cells and human neutrophils in the absence of DNase1 containing serum to avoid chromatin degradation and microfilament disassembly. NET-formation by dHL-60 cells and neutrophils was induced by Ionomycin or phorbol-12-myristat-13-acetate (PMA). Subsequent staining with anti-actin and TRITC-phalloidin showed depolymerization of the cortical F-actin at spatially confined areas, the NET extrusion sites, effected by transient activation of the monooxygenase MICAL-1 supported by the G-actin binding proteins cofilin, profilin, thymosin ß4 and probably the F-actin fragmenting activity of gelsolin and/or its fragments, which also decorated the formed NETs. MICAL-1 itself appeared to be proteolyzed by neutrophil elastase possibly to confine its activity to the NET-extrusion area. The F-actin oxidization activity of MICAL-1 is inhibited by Levosimendan leading to reduced NET-formation. Anti-gasdermin-D immunohistochemistry showed a cytoplasmic distribution in non-stimulated cells. After stimulation the NET-extrusion pore displayed reduced anti-gasdermin-D staining but accumulated underneath the plasma membrane of the remaining cell body. A similar distribution was observed for myosin that concentrated together with cortical F-actin along the periphery of the remaining cell body suggesting force production by acto-myosin interactions supporting NET expulsion as indicated by the inhibitory action of the myosin ATPase inhibitor blebbistatin. Isolated human neutrophils displayed differences in their content of certain cytoskeletal proteins. After stimulation neutrophils with high gelsolin content preferentially formed “cloud”-like NETs, whereas those with low or no gelsolin formed long “filamentous” NETs.
•Actin cytoskeleton alterations during NET extrusion by neutrophil-like dHL-60 cells and human neutrophils were analyzed in the absence of DNase1 containing serum to avoid chromatin degradation and microfilament disassembly. F-actin fragmenting activity by the monooxygenase MICAL-1 supported by the G-actin binding proteins gelsolin cofilin, profilin, and thymosin ß4 was identified to be essential for NET-extrusion. |
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ISSN: | 0171-9335 1618-1298 1618-1298 |
DOI: | 10.1016/j.ejcb.2024.151407 |