Redox Biol|徐颖团队揭示GSH合成启动单核细胞代谢和表观遗传的作用机制

最新细胞功能及机制文献分享
已在植物、无脊椎动物和哺乳动物中报道了训练免疫(一种新发现的免疫模式),即先天免疫系统的非特异性记忆。训练免疫中的单核细胞和巨噬细胞会产生活性氧(ROS),从而触发抗氧化谷胱甘肽(GSH)反应以缓解上升的ROS。然而,GSH合成是否以及如何塑造训练有素的免疫力仍然未知。2021年12月7日,复旦大学生命科学学院遗传学研究所基因工程国家重点实验室徐颖团队在Redox Biology上发表了题为“Glutathione synthesis primes monocytes metabolic and epigenetic pathway for β-glucan-trained immunity”的研究论文。在本研究中,团队通过分析来自携带谷氨酸-半胱氨酸连接酶(Gclc)催化亚基以及GSH的骨髓特异性缺失小鼠的β-葡聚糖训练的骨髓衍生巨噬细胞(BMDMs),表明GSH的抗氧化作用是β-葡聚糖诱导的单核细胞代谢和表观遗传变化所必需的环境。
人体的免疫系统就像一支庞大的特种部队,训练有素的免疫系统描述了先天免疫细胞遇到病原体的免疫记忆的能力,其在二次遭遇入侵后,对这些记忆的回忆表现出了广泛增强的炎症反应,其特征是先天免疫基因的转录增加。训练免疫的特点是表观遗传变化,在转录过程中调节免疫代谢反应基因的可及性。表观遗传与延胡索酸积累、糖酵解、谷氨酰胺分解和胆固醇生物合成等途径的代谢变化存在紧密联系,源自这些途径的代谢物可充当信号分子和辅助因子,进而调节染色质修饰酶的活性。低浓度的ROS支持细胞存活和增殖,但高浓度的ROS会引发DNA损伤和细胞死亡,免疫细胞可通过内源性抗氧化剂,尤其是GSH来调控不断升高的ROS浓度。GSH合成的限速步骤由谷氨酸-半胱氨酸连接酶(GCL)催化,该酶由GCLC和GCLM亚基组成,靶向Gclc可导致小鼠GSH缺乏。
在此项研究中,团队报告了来自小鼠的β-葡聚糖训练的巨噬细胞,这些细胞含有Gclc催化亚基的髓样特异性缺失,显示出GSH合成受损,并减少了促炎细胞因子的产生。此外,Gclc缺失还会影响mTOR的激活以及c-Myc转录因子的表达,导致能量利用受损和代谢重编程,从而致使受β-葡聚糖训练的巨噬细胞转变为糖酵解和谷氨酰胺分解。同时,Gclc缺失也可通过促进EZH2甲基转移酶增强子抑制β-葡聚糖训练的巨噬细胞中免疫代谢基因启动子的H3K27me3去甲基化。体内研究显示,Gclc的骨髓特异性缺失缓解了白色念珠菌再攻击后促炎细胞因子的分泌。最后,利用GCLC抑制剂丁硫氨酸亚砜亚胺(BSO)处理Gclc缺陷小鼠和人外周血单核细胞后,EZH2的药理学抑制增强了针对念珠菌感染的训练免疫反应。
《Redox Biol|徐颖团队揭示GSH合成启动单核细胞代谢和表观遗传的作用机制》

图 本文部分实验结果。

期刊及DOI号

Redox Biol. 2021 Dec 7. 

doi: 10.1016/j.redox.2021.102206.

题目

Glutathione synthesis primes monocytes metabolic and epigenetic pathway for β-glucan-trained immunity

摘要
Trained monocytes and macrophages produce reactive oxygen species (ROS), which trigger antioxidative glutathione (GSH) response to buffer the rising ROS. However, whether and how the trained immunity is shaped by GSH synthesis remains unknown. Here, we report that β-glucan-trained macrophages from mice harboring a myeloid-specific deletion of the catalytic subunit of glutamate-cysteine ligase (Gclc) showed impaired GSH synthesis and decreased proinflammatory cytokine production in response to lipopolysaccharide challenge. Gclc deficiency compromised the activation of mammalian target of rapamycin-1 (mTOR) and expression of c-Myc transcription factors, abrogating the energy utilization and the metabolic reprogramming that allows β-glucan-trained macrophages to switch to glycolysis and glutaminolysis. Furthermore, Gclc deletion repressed effective H3K27me3 demethylation in the promoters of immunometabolic genes, such as Gls, Hk2, and Glut1, in β-glucan-trained macrophages by promoting the methyltransferase enhancer of zeste homolog 2 (EZH2). In vivo, myeloid-specific ablation of Gclc decreased the secretion of proinflammatory cytokines upon rechallenge with Candida albicans and these animals were less protected against the infection, compared with control littermates. Moreover, pharmacological inhibition of EZH2 enhanced the trained immunity response against Candida infection in Gclc-deficient mouse and human peripheral blood mononuclear cells treated with GCLC inhibitor buthionine sulfoximine (BSO). Thus, antioxidative GSH synthesis supports an environment conducive to β-glucan-induced metabolic and epigenetic reprogramming in trained immunity, allowing exploration of its functional consequences in autoimmune or inflammatory disease.
关键词:Trained immunity; Innate immune memory; Catalytic subunit of glutamate-cysteine ligase; ROS; GSH
《Redox Biol|徐颖团队揭示GSH合成启动单核细胞代谢和表观遗传的作用机制》
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