Heat shock-induced apoptosis

热休克诱导细胞凋亡

基本信息

批准号：
8017397
负责人：
Shawn B Bratton
金额：
$ 29.23万
依托单位：
UNIVERSITY OF TEXAS AT AUSTIN
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-04-08 至 2011-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8017397
关键词：
Address Alkalinization Apoptosis Apoptosis Inhibitor Apoptotic Applications Grants Area Attenuated Caspase Cathepsins Cathepsins B Cell Death Cells Cleaved cell Clinic Clinical Trials Complex Convulsive therapy Cytoplasm Cytoplasmic Granules Cytosol Data Embryo Environment Family member Fever Fibroblasts Future Gene Combinations Grant Health Heat shock proteins Heat-Shock Proteins 70 Heat-Shock Response Heating Imidazole Investigation Lead Light MAP Kinase Kinase Kinase Malignant Neoplasms Mediating Membrane Mitochondria Mitogen-Activated Protein Kinase Kinases Modeling Mus N-terminal Outer Mitochondrial Membrane Pathway interactions Pharmaceutical Preparations Phase Phosphotransferases Process Proteins Protons Publications RNA Interference RNA-Binding Proteins Radiation Radiation therapy Regulation Reporting Resistance Role Signal Transduction Stimulus Stream Stress TNF Receptor-Associated Factors TNF receptor-associated factor 2 Testing Tumor Necrosis Factor Receptor Work aposome base caspase-2 caspase-3 cell killing cellular targeting chemotherapy endoplasmic reticulum stress improved inhibitor/antagonist insight interest novel overexpression prevent pro-caspase-3 response stress-activated protein kinase 1

项目摘要

DESCRIPTION (provided by applicant): Hyperthermia or heat shock therapy is currently being utilized in phase II/III clinical trials, either alone or in combination with radiation or chemotherapy, for the treatment of various cancers. Unfortunately, though intense heat shock induces apoptosis, the underlying mechanisms remain controversial and unclear. We have recently shown that heat shock does not require any of the known initiator caspases or their activating complexes to induce apoptosis. We now hypothesize that heat shock induces cell death, in part by stimulating rapid endo-lysosomal membrane permeabilization (ELMP), which coincides with cytosolic acidification and release of cathepsins into the cytoplasm, both of which participate in the processing of procaspase-3 and the proapoptotic BH3-only protein Bid. Importantly, heat shock-induced mitochondrial outer membrane permeabilization (MOMP) is essential for cell death, as cells that overexpress Bcl-2-or are deficient in Bid or the proapoptotic Bcl-2 family members Bax and Bak-are resistant to cell death. MOMP is critical for cell death most likely because it facilitates the release of inhibitor of apoptosis (IAP) antagonists, which in turn promote caspase activity. Remarkably, heat shock also requires c-Jun N-terminal kinases (JNKs) to induce MOMP, and we find that JNKs are activated through a highly novel pathway involving the formation of so-called cytoplasmic "stress granules" (SGs). We hypothesize that formation of SGs is initiated through heat-induced aggregation of the RNA binding protein TIA-1, and that SGs in turn activate JNKs through a tumor necrosis factor (TNF) receptor-associated factor 2 (TRAF2) and TGF2- activating kinase 1 (TAK1)-dependent pathway. We further speculate that JNKs sensitize cells to heat shock-induced MOMP by activating additional BH3-only proteins, such as Bim, and/or by inhibiting specific antiapoptotic Bcl-2 family members, such as Bcl-xL or Mcl-1. In the following three specific aims, we propose (1) to determine if ELMP elicits cytosolic acidification and to determine how ELMP is regulated by heat shock protein 70 (Hsp70), (2) to establish the roles of cathepsins in the activation of procaspase-3 and Bid, and (3) to characterize the unique SG-TRAF2-TAK1-MAPKK-JNK pathway, its regulation by Hsp70, and the downstream targets of JNK following heat shock. In summary, this grant proposal would determine the basic mechanisms of heat shock-induced apoptosis, which are highly relevant given the renewed interest in hyperthermia as a clinically useful treatment option. PUBLIC HEALTH RELEVANCE: The focus of this grant project is to unravel the cellular mechanisms that mediate heat shock-induced cell death. Heat shock, or hyperthermia, is currently being used in clinical trials, either alone or as an adjunct to chemo- or radiotherapy for the treatment of various cancers. Unfortunately, very little is known about how heat shock kills cells. Our preliminary work in this area suggests that heat shock induces cell death through mechanisms that are very different from other types of stimuli. Thus, it is anticipated that the work proposed herein will significantly improve our understanding of how heat shock works in the clinic and may shed light on new pathways that can be exploited therapeutically in the future.

描述（由申请人提供）：热疗或热休克疗法目前正在 II/III 期临床试验中单独使用或与放疗或化疗联合使用，用于治疗各种癌症。不幸的是，尽管强烈的热休克会诱导细胞凋亡，但其潜在机制仍然存在争议和不清楚。我们最近表明，热休克不需要任何已知的起始半胱天冬酶或其激活复合物来诱导细胞凋亡。我们现在假设热休克诱导细胞死亡，部分是通过刺激快速内溶酶体膜透化（ELMP），这与胞质酸化和组织蛋白酶释放到细胞质中同时发生，两者都参与 procaspase-3 和仅促凋亡 BH3 蛋白 Bid。重要的是，热休克诱导的线粒体外膜透化 (MOMP) 对于细胞死亡至关重要，因为过度表达 Bcl-2- 或 Bid 缺陷或促凋亡 Bcl-2 家族成员 Bax 和 Bak- 的细胞能够抵抗细胞死亡。 MOMP 对于细胞死亡至关重要，很可能是因为它促进细胞凋亡抑制剂 (IAP) 拮抗剂的释放，从而促进 caspase 活性。值得注意的是，热休克还需要 c-Jun N 末端激酶 (JNK) 来诱导 MOMP，我们发现 JNK 通过一种高度新颖的途径被激活，该途径涉及所谓的细胞质“应激颗粒”(SG) 的形成。我们假设 SG 的形成是通过热诱导 RNA 结合蛋白 TIA-1 的聚集启动的，并且 SG 反过来通过肿瘤坏死因子 (TNF) 受体相关因子 2 (TRAF2) 和 TGF2 激活激酶激活 JNK 1 (TAK1) 依赖性途径。我们进一步推测，JNK 通过激活额外的 BH3-only 蛋白（例如 Bim）和/或通过抑制特定的抗凋亡 Bcl-2 家族成员（例如 Bcl-xL 或 Mcl-1）使细胞对热休克诱导的 MOMP 敏感。在以下三个具体目标中，我们建议 (1) 确定 ELMP 是否引起胞质酸化，并确定 ELMP 如何受热休克蛋白 70 (Hsp70) 调节，(2) 确定组织蛋白酶在激活天冬氨酸前体中的作用3 和 Bid，以及 (3) 表征独特的 SG-TRAF2-TAK1-MAPKK-JNK 通路、其受 Hsp70 的调节以及下游靶标JNK 热休克后。总之，这项拨款提案将确定热休克诱导的细胞凋亡的基本机制，鉴于人们对热疗作为临床上有用的治疗选择重新产生兴趣，这一机制具有高度的相关性。公共健康相关性：该资助项目的重点是揭示介导热休克诱导的细胞死亡的细胞机制。热休克或热疗目前正在临床试验中使用，可以单独使用，也可以作为化疗或放疗的辅助疗法来治疗各种癌症。不幸的是，人们对热休克如何杀死细胞知之甚少。我们在这一领域的初步工作表明，热休克通过与其他类型的刺激非常不同的机制诱导细胞死亡。因此，预计本文提出的工作将显着提高我们对热休克在临床中如何发挥作用的理解，并可能揭示未来可用于治疗的新途径。