SerpinB1 is critical for neutrophil survival through cell-autonomous inhibition of cathepsin G
SerpinB1 is critical for neutrophil survival through cell-autonomous inhibition of cathepsin G
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DOI：
10.1182/blood-2012-09-455022
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发表时间：
2013-05-09
期刊：
影响因子：
20.3
通讯作者：
Benarafa, Charaf
中科院分区：
文献类型：
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作者：
Baumann, Mathias;Pham, Christine T. N.;Benarafa, Charaf
骨髓 (BM) 拥有大量多形核中性粒细胞 (PMN) 储备，它们会迅速动员到循环系统和组织中以响应危险信号。 SerpinB1 是中性粒细胞丝氨酸蛋白酶中性粒细胞弹性蛋白酶 (NE) 和组织蛋白酶 G (CG) 的有效抑制剂。 SerpinB1 缺陷 (sB1(-/-)) 导致 BM PMN 储备严重减少并且无法清除细菌感染。使用 BM 嵌合体，我们发现 BM 细胞中的 serpinB1 缺陷对于重现 sB1(-/-) 小鼠的 BM 中性粒细胞减少症是必要且充分的。此外，我们还发现，CG（而非 NE）的基因删除可以完全挽救 sB1(-/-) 小鼠的 BM 中性粒细胞减少症。在混合 BM 嵌合体和体外存活研究中，我们表明 CG 通过细胞内在途径调节 sB1(-/-) PMN 存活。此外，溶酶体剂 L-亮氨酰-L-亮氨酸甲酯的膜透化允许颗粒内容物释放到胞质中，足以通过 CG 依赖性途径诱导 PMN 快速死亡。 CG 介导的 PMN 细胞毒性仅被 caspase 抑制部分阻断，这表明 CG 在细胞凋亡过程中裂解一组不同的靶标。总之，我们揭示了丝氨酸蛋白酶 CG 的新细胞毒功能，并表明 serpinB1 通过拮抗细胞内 CG 活性对于维持 PMN 存活至关重要。
Bone marrow (BM) holds a large reserve of polymorphonuclear neutrophils (PMNs) that are rapidly mobilized to the circulation and tissues in response to danger signals. SerpinB1 is a potent inhibitor of neutrophil serine proteases neutrophil elastase (NE) and cathepsin G (CG). SerpinB1 deficiency (sB1(-/-)) results in a severe reduction of the BM PMN reserve and failure to clear bacterial infection. Using BM chimera, we found that serpinB1 deficiency in BM cells was necessary and sufficient to reproduce the BM neutropenia of sB1(-/-) mice. Moreover, we showed that genetic deletion of CG, but not NE, fully rescued the BM neutropenia in sB1(-/-) mice. In mixed BM chimera and in vitro survival studies, we showed that CG modulates sB1(-/-) PMN survival through a cell-intrinsic pathway. In addition, membrane permeabilization by lysosomotropic agent L-leucyl-L-leucine methyl ester that allows cytosolic release of granule contents was sufficient to induce rapid PMN death through a CG-dependent pathway. CG-mediated PMN cytotoxicity was only partly blocked by caspase inhibition, suggesting that CG cleaves a distinct set of targets during apoptosis. In conclusion, we have unveiled a new cytotoxic function for the serine protease CG and showed that serpinB1 is critical for maintaining PMN survival by antagonizing intracellular CG activity.