Department of Medicine 3 - Rheumatology and Immunology, Friedrich-Alexander-Universität Erlangen-Nürnberg and Uniklinikum Erlangen, Erlangen, Germany.
Deutsches Zentrum Für Immuntherapie (DZI), Friedrich-Alexander-Universität Erlangen-Nürnberg and Uniklinikum Erlangen, Erlangen, Germany.
Cell Commun Signal. 2024 Sep 9;22(1):435. doi: 10.1186/s12964-024-01785-6.
The inducers of neutrophil extracellular trap (NET) formation are heterogeneous and consequently, there is no specific pathway or signature molecule indispensable for NET formation. But certain events such as histone modification, chromatin decondensation, nuclear envelope breakdown, and NET release are ubiquitous. During NET formation, neutrophils drastically rearrange their cytoplasmic, granular and nuclear content. Yet, the exact mechanism for decoding each step during NET formation still remains elusive. Here, we investigated the mechanism of nuclear envelope breakdown during NET formation. Immunofluorescence microscopic evaluation revealed a gradual disintegration of outer nuclear membrane protein nesprin-1 and alterations in nuclear morphology during NET formation. MALDI-TOF analysis of NETs that had been generated by various inducers detected the accumulation of nesprin-1 fragments. This suggests that nesprin-1 degradation occurs before NET release. In the presence of a calpain-1, inhibitor nesprin-1 degradation was decreased in calcium driven NET formation. Microscopic evaluation confirmed that the disintegration of the lamin B receptor (LBR) and the collapse of the actin cytoskeleton occurs in early and later phases of NET release, respectively. We conclude that the calpain-1 degrades nesprin-1, orchestrates the weakening of the nuclear membrane, contributes to LBR disintegration, and promoting DNA release and finally, NETs formation.
中性粒细胞胞外诱捕网（NET）形成的诱导剂具有异质性，因此，没有特定的途径或特征分子是 NET 形成所必需的。但某些事件，如组蛋白修饰、染色质解凝聚、核膜破裂和 NET 释放是普遍存在的。在 NET 形成过程中，中性粒细胞会剧烈地重新排列其细胞质、颗粒和核内容物。然而，解码 NET 形成过程中每个步骤的确切机制仍然难以捉摸。在这里，我们研究了 NET 形成过程中核膜破裂的机制。免疫荧光显微镜评估显示，在外核膜蛋白 nesprin-1 逐渐解体，并在 NET 形成过程中改变核形态。通过各种诱导剂生成的 NET 的 MALDI-TOF 分析检测到 nesprin-1 片段的积累。这表明 nesprin-1 的降解发生在 NET 释放之前。在钙调蛋白-1 抑制剂存在的情况下，钙驱动的 NET 形成中 nesprin-1 的降解减少。显微镜评估证实，lamin B 受体（LBR）的解体和肌动蛋白细胞骨架的崩溃分别发生在 NET 释放的早期和晚期阶段。我们得出结论，钙调蛋白-1 降解 nesprin-1，协调核膜的弱化，有助于 LBR 的解体，并促进 DNA 的释放，最终形成 NET。
