摘要
内质网应激参与肿瘤的发生与发展,近年来,内质网应激对T细胞发育和功能调控的研究也逐渐深入。肿瘤微环境中浸润的T细胞内质网应激的发生加剧T细胞的耗竭,损害T细胞抗肿瘤免疫功能。内质网应激抑制剂的使用可以减轻T细胞的耗竭程度,改善肿瘤微环境中T细胞的抗肿瘤功能。此外,一些时钟基因如Per1和Per2的下调也促进了T细胞耗竭的进展,而内质网应激通路的效应分子能够调控生物钟网络中Per基因家族的转录,增强T细胞的免疫功能。本文就内质网应激调控T细胞的抗肿瘤功能进行论述,为肿瘤免疫治疗提供新策略。
内质网是胞内蛋白质折叠、成熟和运输的主要场所。哺乳动物约三分之一的新生多肽链需要经过内质网的加工和转运,故生理状态下,内质网腔中分布着成千上万种不同状态的多肽链和新生蛋白。为了确保蛋白质在内质网网腔中有条不紊地进行正常修饰、折叠和转运,内质网进化出了强大的蛋白质质量控制系统。该系统可感知细胞的蛋白折叠负荷以及网腔中未折叠及错折叠的蛋白质,来调控内质网的蛋白质折叠能力和内质网相关蛋白质降解(endoplasmic reticulum associated degradation, ERAD)。在不利的细胞内外环境等多重因素的影响下,蛋白质的正确折叠被阻滞或破坏,未折叠蛋白和错误折叠蛋白在胞内累积,诱发细胞强烈的内质网应
T细胞在胸腺发育成熟,先后经历CD
众多研究表明,肿瘤细胞发生内质网应激以提高内质网的蛋白质加工能力进而满足自身增殖和代谢需求,促进肿瘤进
免疫球蛋白结合蛋白(binding-immunoglobulin protein, BiP)是内质网膜上的一类驻留蛋白,是Hsp70伴侣蛋白家族中的一种。在正常生理情况下,BiP与内质网膜上的3类传感器结合以抑制它们的激活。但是在内质网应激发生时,BiP与错折叠蛋白具有更高的亲和力,因而从传感器上解离下来。与BiP解离的3类传感器被激活,进一步介导下游信号通路的活
PERK是真核翻译起始因子2亚基α(eukaryotic translation initiation factor 2 subunit-α,eIF2α)的激酶,PERK感应到内质网应激信号后,迅速磷酸化eIF2
3种内质网应激感受器中,IRE1α在进化上高度保守,在植物和酵母细胞中也都有发
在内质网应激条件下,ATF6会转位到高尔基体,在高尔基体被位点1蛋白酶(site-1 protease,S1P)和位点2蛋白酶(site-2 protease,S2P)切割,释放出N端具有转录活性的片段ATF6P50发挥作
许多研究表明,PERK通路的激活会抑制T细胞的抗肿瘤功能。研究表明,卵巢癌临床患者肿瘤组织浸润的CD
Hurst
调节性T细胞(regulatory T cells,Treg)是CD
因此,PERK信号通路在T细胞中的激活对T细胞的抗肿瘤功能的发挥是不利的。通过药物抑制PERK在T细胞中的激活可以有效改善T细胞的抗肿瘤功能,这也成为免疫治疗的一个潜在靶点,具有深入研究的价值。
近期研究显示,IRE1α/XBP1通路能够调控T细胞的抗肿瘤免疫。Song
此外,Ma
因此,控制内质网应激或者靶向抑制IRE1α/XBP1信号通路可能有助于恢复肿瘤浸润T细胞的代谢适应性和抗肿瘤能力。
与PERK和IRE1α不同的是,ATF6对T细胞的调控功能鲜有报道。Wu
内质网应激参与糖尿病和多种器官纤维化的病理进程,癌细胞内质网应激的发生也会加速肿瘤进展,因此针对内质网应激已经有多种抑制剂被开发和报
自第一个靶向内质网应激的药物硼替佐米用于临床以
哺乳动物为了适应昼夜变化,进化出完整的生物钟系统来调节机体的生理活动,故时钟基因在各种组织细胞中均有表
在T细胞以外,生物节律通过内质网应激PERK通路的激活介导肝脏衰
内质网应激已在许多癌症中被证实参与肿瘤的发生和发展。肿瘤微环境低氧、低糖、低pH和氧化应激等不利因素,以及肿瘤细胞自身过度的蛋白质合成需求诱发肿瘤细胞内质网应激,激发肿瘤细胞适应性的未折叠蛋白反应和强大的增殖潜力,加快肿瘤的生
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