NETosis proceeds by cytoskeleton and endomembrane disassembly and PAD4-mediated chromatin decondensation and nuclear envelope rupture
Open Access
- 13 March 2020
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 117 (13), 7326-7337
- https://doi.org/10.1073/pnas.1909546117
Abstract
Neutrophil extracellular traps (NETs) are web-like DNA structures decorated with histones and cytotoxic proteins that are released by activated neutrophils to trap and neutralize pathogens during the innate immune response, but also form in and exacerbate sterile inflammation. Peptidylarginine deiminase 4 (PAD4) citrullinates histones and is required for NET formation (NETosis) in mouse neutrophils. While the in vivo impact of NETs is accumulating, the cellular events driving NETosis and the role of PAD4 in these events are unclear. We performed high-resolution time-lapse microscopy of mouse and human neutrophils and differentiated HL-60 neutrophil-like cells (dHL-60) labeled with fluorescent markers of organelles and stimulated with bacterial toxins or Candida albicans to induce NETosis. Upon stimulation, cells exhibited rapid disassembly of the actin cytoskeleton, followed by shedding of plasma membrane microvesicles, disassembly and remodeling of the microtubule and vimentin cytoskeletons, ER vesiculation, chromatin decondensation and nuclear rounding, progressive plasma membrane and nuclear envelope (NE) permeabilization, nuclear lamin meshwork and then NE rupture to release DNA into the cytoplasm, and finally plasma membrane rupture and discharge of extracellular DNA. Inhibition of actin disassembly blocked NET release. Mouse and dHL-60 cells bearing genetic alteration of PAD4 showed that chromatin decondensation, lamin meshwork and NE rupture and extracellular DNA release required the enzymatic and nuclear localization activities of PAD4. Thus, NETosis proceeds by a stepwise sequence of cellular events culminating in the PAD4-mediated expulsion of DNA.Keywords
Funding Information
- HHS | NIH | National Heart, Lung, and Blood Institute (ZIA HL005104)
- National Institute of Health (RO1 GM106023)
- National Institute of Health (PO1 GM096971)
- National Institute of Health (T32 CA08062160038140)
- National Institue of Health (R35 HL135765)
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