Heat shock-induced apoptosis

热休克诱导细胞凋亡

• 批准号: 7466018
• 负责人: Shawn B Bratton
• 金额: $ 30.13万
• 依托单位: UNIVERSITY OF TEXAS AT AUSTIN
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-08 至 2013-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7466018
• 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; Endoplasmic Reticulum; Environment; Family member; Fever; Fibroblasts; Future; Gene Combinations; Grant; 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; Outer Mitochondrial Membrane; Pathway interactions; Pharmaceutical Preparations; Phase; Phosphotransferases; Process; Protein Overexpression; Proteins; Protons; Public Health; 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; TRAF2 gene; Testing; Tumor Necrosis Factor Receptor; Tumor Necrosis Factor-alpha; Tumor Necrosis Factors; Work; aposome; base; caspase-2; caspase-3; cell killing; cellular targeting; chemotherapy; human TNF protein; hyperthermia treatment; improved; inhibitor/antagonist; insight; interest; novel; prevent; pro-caspase-3; response; stress-activated protein kinase 1

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期临床试验中使用，可以单独使用，也可以与放疗或化疗联合使用，用于治疗各种癌症。不幸的是，尽管强烈的热休克诱导细胞凋亡，其潜在的机制仍然存在争议和不清楚。我们最近的研究表明，热休克不需要任何已知的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，部分原因是通过刺激快速内溶酶体膜渗透（ELMP），这与细胞质酸化和组织蛋白酶释放到细胞质中相一致，这两者都参与procaspase-3和促凋亡的BH3-only蛋白Bid的加工。重要的是，热休克诱导的线粒体外膜透性（MOMP）对细胞死亡至关重要，因为过度表达Bcl-2或缺乏Bid或促凋亡的Bcl-2家族成员Bax和bak的细胞对细胞死亡具有抗性。MOMP对细胞死亡至关重要，很可能是因为它促进了凋亡抑制剂（IAP）拮抗剂的释放，进而促进了半胱天冬酶的活性。值得注意的是，热休克还需要c-Jun n -末端激酶（JNKs）来诱导MOMP，我们发现JNKs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”（SGs）的形成。我们假设SGs的形成是通过RNA结合蛋白TIA-1的热诱导聚集开始的，并且SGs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1 （TAK1）依赖途径激活JNKs。我们进一步推测，JNKs通过激活额外的BH3-only蛋白（如Bim）和/或抑制特定的抗凋亡Bcl-2家族成员（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，我们提出(1)确定ELMP是否引发细胞质酸化，并确定ELMP如何受到热休克蛋白70 （Hsp70）的调节，(2)确定组织蛋白酶在procaspase-3和Bid激活中的作用，以及(3)表征独特的SG-TRAF2-TAK1-MAPKK-JNK途径，Hsp70对其的调节，以及JNK在热休克后的下游靶点。总之，这项拨款提案将确定热休克诱导细胞凋亡的基本机制，这与热疗作为临床有效治疗选择的新兴趣高度相关。公共卫生相关性：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，既可以单独使用，也可以作为化疗或放疗的辅助手段，用于治疗各种癌症。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，热休克诱导细胞死亡的机制与其他类型的刺激非常不同。因此，预计本文提出的工作将显著提高我们对临床热休克如何起作用的理解，并可能揭示未来可用于治疗的新途径。