AQP8 transports NOX2-generated H2O2 across the plasma membrane to promote signaling in B cells
AQP8 transports NOX2-generated H2O2 across the plasma membrane to promote signaling in B cells
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DOI：
10.1189/jlb.2ab0116-045r
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发表时间：
2016-11-01
影响因子：
5.5
通讯作者：
Sitia, Roberto
中科院分区：
文献类型：
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作者：
Bertolotti, Milena;Farinelli, Giada;Sitia, Roberto
H2 O2在关键信号通路中作为第二信使，瞬时调节酪氨酸磷酸酶和激酶。我们研究了它的起源、膜转运和在B细胞活化和分化过程中的功能作用。我们的数据确定NADPH氧化酶2作为H2 O2的主要来源和水通道蛋白8作为跨质膜的运输促进剂。在水通道蛋白8沉默的情况下，诱导型B淋巴瘤细胞对TLR和BCR刺激的反应较差。它们的分化严重受损，表现为IgM聚合的延迟发生、IgM分泌量低和细胞表面BCR表达延长。抗沉默的水通道蛋白8拯救了反应性，证实了H2 O2跨膜输入对B细胞活化是必不可少的。向原代B脾细胞中加入外源性过氧化氢酶严重损害了BCR交联诱导的酪氨酸磷酸化，在慢性肉芽肿病小鼠模型中缺乏NOX 2也是如此。重要的是，通过基因治疗重新表达gp 91（phox）恢复了NOX 2（-/-）细胞中特异性B细胞信号传导缺陷。因此，B细胞活化和分化的有效诱导需要完整的H2 O2通量穿过质膜用于信号放大。
H2O2 acts as a second messenger in key signaling circuits, transiently modulating tyrosine phosphatases and kinases. We investigated its origin, membrane transport, and functional role during B cell activation and differentiation. Our data identified NADPH-oxidase 2 as the main source of H2O2 and aquaporin 8 as a transport facilitator across the plasma membrane. On aquaporin 8 silencing, inducible B lymphoma cells responded poorly to TLR and BCR stimulation. Their differentiation was severely impaired, as demonstrated by retarded onset of IgM polymerization, low amounts of IgM secretion, and prolonged BCR expression on the cell surface. A silencing-resistant aquaporin 8 rescued responsiveness, confirming that the import of H2O2 across the membrane is essential for B cell activation. The addition of exogenous catalase to primary B splenocytes severely impaired the tyrosine phosphorylation induced by BCR cross-linking, as did the absence of NOX2 in a murine model of chronic granulomatous disease. Importantly, re-expression of gp91(phox) through gene therapy restored the specific B cell signaling deficiency in NOX2(-/-) cells. Thus, efficient induction of B cell activation and differentiation requires intact H2O2 fluxes across the plasma membrane for signal amplification.