Granzyme a Pathway of CTL-Mediated Cell Death

颗粒酶是 CTL 介导的细胞死亡的途径

• 批准号: 6827035
• 负责人: Judy Lieberman
• 金额: $ 52.41万
• 依托单位: IMMUNE DISEASE INSTITUTE, INC.
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6827035
• 关键词: DNA damage; apoptosis; cell mediated cytotoxicity; cysteine endopeptidases; cytolysins; cytotoxic T lymphocyte; deoxyribonuclease I; enzyme mechanism; expression cloning; genetically modified animals; laboratory mouse; mitochondria; molecular cloning; natural killer cells; pore forming protein; serine proteinases; stress proteins

DESCRIPTION (provided by applicant): Cytotoxic T lymphocytes (CTL) and natural killer (NK) cells exocytose cytotoxic granules to induce apoptosis of virally infected or tumor targets. Cytotoxic granules contain perforin, a pore-forming protein, and a group of serine proteases, called granzymes (Gzm), in a proteoglycan matrix. Perforin and either GzmA or GzmB is sufficient for granule-mediated lysis by CTL, but mice deficient in either Gzm may be impaired in defense against some viral infections. GzmB activates a ubiquitous apoptotic cascade induced by cleavage of caspases and can also directly cleave some key caspase pathway substrates. However, CTL granule mediated cytolysis is virtually unimpaired in the setting of complete caspase blockade. GzmA, the most abundant Gzm, activates a novel caspase-independent apoptotic pathway. The goal of this proposal is to continue to unravel the mechanism of action of GzmA, building on the research accomplished during the previous funding. GzmA, delivered into target cells via perforin, induces single-stranded DNA damage as Nell as apoptotic morphology and loss of cell membrane integrity. A special target of the GzmA cell death pathway is a 270-440 kDa endoplasmic reticulum-associated complex, called the SET complex, which contains three GzmA substrates, the nucleosome assembly protein SET, the DNA bending protein HMG-2 and the apurinic endonuclease (Ape1) in base excision repair (BER). GzmA cleavage of Ape1 makes target cell repair of GzmA-induced damage unlikely. The SET complex also contains the GzmA-activated DNase, NM23-H1, which is activated when GzmA cleaves its specific inhibitor, the SET protein. The competing renewal of this grant will investigate the kinetics of GzmA-mediated damage within target cells; determine the mitochondrial effects of GzmA; identify the remaining components of the SET complex and seek to understand further the role of the SET complex in normal cellular function and in GzmA-mediated cell death; and investigate the effect of GzmA on other DNA repair pathways, besides BER.

描述（由申请人提供）：细胞毒性T淋巴细胞（CTL）和天然杀伤（NK）细胞胞囊细胞毒性颗粒诱导病毒感染或肿瘤靶标的细胞凋亡。细胞毒性颗粒中含有孔子蛋白，孔形成蛋白质和一组丝氨酸蛋白酶，称为颗粒蛋白酶（GZM），在蛋白聚糖基质中。 Perforin和GZMA或GZMB足以容纳CTL颗粒介导的裂解，但是在防御某些病毒感染的防御时，缺乏任何GZM的小鼠可能会​​受到损害。 GZMB激活caspase裂解引起的无处不在的凋亡级联反应，也可以直接裂解一些关键的caspase途径。然而，在完全caspase阻塞的情况下，CTL颗粒介导的胞解介导的细胞解析实际上没有受损。 GZMA是最丰富的GZM，它激活了一种新型的与caspase无关的凋亡途径。该提案的目的是继续揭示GZMA的作用机理，这是基于上一次资助期间所完成的研究的基础。 GZMA通过穿孔蛋白传递到靶细胞中，诱导单链DNA损伤，如凋亡形态和细胞膜完整性的丧失。 GZMA细胞死亡的特殊目标 途径是一种270-440 kDa内质网相关的复合物，称为SET复合物，其中包含三个GZMA底物，即核小体组装蛋白套件，DNA弯曲蛋白HMG-2和阿椎骨内核酸内核酶（APE1）在基础基cecepision Repair（Ber）中。 APE1的GZMA切割使GZMA诱导的损伤的靶细胞修复不可能。该集合复合物还包含GZMA激活的DNase NM23-H1，当GZMA裂解其特异性抑制剂（固定蛋白）时，它被激活。该赠款的竞争更新将研究靶细胞内GZMA介导的损伤的动力学；确定GZMA的线粒体效应；确定集合复合物的剩余成分，并试图进一步了解集合复合物在正常细胞功能和GZMA介导的细胞死亡中的作用；并研究GZMA对其他DNA修复途径的影响。