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: 6883217
• 负责人: Judy Lieberman
• 金额: $ 53.98万
• 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/6883217
• 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）和自然杀伤细胞（NK）分泌细胞毒性颗粒，诱导病毒感染或肿瘤目标细胞凋亡。细胞毒性颗粒在蛋白聚糖基质中含有穿孔素，一种成孔蛋白和一组丝氨酸蛋白酶，称为颗粒酶（Gzm）。穿孔素和GzmA或GzmB中的任何一种都足以通过CTL进行颗粒介导的裂解，但Gzm缺乏的小鼠对某些病毒感染的防御能力可能受损。GzmB激活了由caspase切割引起的普遍的凋亡级联反应，也可以直接切割一些关键的caspase途径底物。然而，在完全阻断半胱天冬酶的情况下，CTL颗粒介导的细胞溶解几乎没有受损。GzmA是最丰富的Gzm，激活一种新的不依赖于caspase的凋亡途径。本提案的目标是在之前资助期间完成的研究基础上，继续揭示GzmA的作用机制。GzmA通过穿孔素进入靶细胞，诱导单链DNA损伤、细胞凋亡形态和细胞膜完整性丧失。GzmA细胞死亡的特殊靶点