Cleavage of Bcl-xL by Caspases contributes to cell death in vivo

Caspases 对 Bcl-xL 的裂解导致体内细胞死亡

基本信息

批准号：
9050122
负责人：
Jason Huska
金额：
$ 4.36万
依托单位：
JOHNS HOPKINS UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-01-01 至 2017-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9050122
关键词：
Address Affect Affinity Age Aging Animals Apoptosis Apoptotic Architecture Atrophic Autoimmune Diseases BCL-2 Protein BCL2 gene Binding Body Weight decreased Bone Marrow CD8B1 gene Caspase Cell Death Cell Death Process Cells Cellularity Cessation of life Chimera organism Cleaved cell Communicable Diseases Cues Cytotoxic T-Lymphocytes Data Development Elderly Event Failure Family member Generations Goals Granzyme Immune response Immunity Influenza Knock-in Mouse Life Maintenance Malignant Neoplasms Mediating Mus Mutate Pattern Population Positioning Attribute Production Protein Family Proteins Resistance Role Signal Transduction Site Surface T cell response T-Cell Development T-Cell Receptor T-Lymphocyte Testing Thymocyte Development Thymocyte Selection Thymus Gland Transgenic Mice Tyrosine Virus aged base burden of illness cell killing cell mediated lymphocytolysis test immunosenescence in vivo influenzavirus inhibitor/antagonist insight killings knockin animal mortality mouse model neglect perforin prevent public health relevance response thymocyte

项目摘要

DESCRIPTION (provided by applicant): The goal for this project is to determine how cleavage of Bcl-xL by caspases contributes to cell death in vivo. Caspase cleavage of cellular substrates is a key event in mediating apoptosis. The Bcl-2 family member Bcl-xL is an inhibitor of apoptotic cell death, and can also be a substrate of caspases. Cleavage of Bcl-xL [not only abolishes its anti-death activity] but also convert Bcl-xL from a potent anti-apoptotic protein to potent pro-death molecule. Cells transfected with the N-terminally truncated Bcl-xL cleavage fragment (ΔN-Bcl-xL) display accelerated cell death. To probe the in vivo effects of Bcl-xL cleavage, a caspase-uncleavable Bcl-xL knock-in mouse was generated by mutating the two caspase cleavage sites within Bcl-xL. Interestingly, caspase-resistant Bcl-xL mice retain a healthy thymus in old age suggesting that cleavage of Bcl-xL leads to cell death that results in thymic atrophy. My preliminary data suggest that these mice may have defective positive selection (generation of a viable T-cell receptor). Therefore, we will explore the possibility that caspase-cleavage of Bcl-xL kills developing thymocytes that fail the positive selection checkpoint. By doing so, we will provide mechanistic insights into what is termed "death by neglect", the failure of thymocytes to receive survival cues. Because these mice maintain a morphologically normal thymus throughout life, I will determine if they also maintain normal immune responses to influenza virus. Influenza particularly affects the elderly, who display poor T-cell responses to the virus. This is presumed to be because of immunosenescence, in part attributed to thymic atrophy. A long-standing assumption is that thymic atrophy contributes to waning immune responses due to decreased T-cell production, but mouse models to definitively test this hypothesis have been lacking. Therefore, we are in a unique position to determine if preserved thymic function also confers protection from influenza infection in aged animals. We will critically evaluate whether thymic atrophy compromises the immune responses needed to control influenza. These studies will also address the role of thymic selection and T-cell contributions to influenza virus immunity.

描述（由申请人提供）：该项目的目标是确定半胱天冬酶对 Bcl-xL 的裂解如何导致体内细胞死亡。半胱天冬酶对细胞底物的裂解是介导细胞凋亡的关键事件。 -xL 是凋亡细胞死亡的抑制剂，也可以是 Bcl-xL 的底物 [不仅废除其作用。抗死亡活性]，而且还将 Bcl-xL 从有效的抗凋亡蛋白转化为有效的促死亡分子。用 N 末端截短的 Bcl-xL 切割片段 (ΔN-Bcl-xL) 转染的细胞显示出加速的细胞死亡。为了探究 Bcl-xL 裂解的体内效应，通过突变这两种蛋白，生成了 caspase 不可裂解的 Bcl-xL 敲入小鼠。 Bcl-xL 内的 caspase 裂解位点不同意，caspase 抗性 Bcl-xL 小鼠在老年时仍保留健康的胸腺，这表明 Bcl-xL 的裂解导致细胞死亡，从而导致胸腺萎缩。因此，我们将探讨有缺陷的阳性选择（产生可行的 T 细胞受体）。 Bcl-xL 的半胱天冬酶裂解会杀死无法通过正选择检查点的正在发育的胸腺细胞，通过这样做，我们将为所谓的“忽视死亡”（胸腺细胞无法接受生存线索）提供机制见解。一生中胸腺形态正常，我将确定它们是否也保持对流感病毒的正常免疫反应。流感特别影响老年人，他们对病毒的 T 细胞反应较差。推测是由于免疫衰老，部分归因于胸腺萎缩。长期以来的一个假设是，胸腺萎缩会导致 T 细胞产生减少，导致免疫反应减弱，但缺乏明确检验这一假设的小鼠模型。我们处于独特的地位，可以确定保留的胸腺功能是否也能保护老年动物免受流感感染。我们将严格评估胸腺萎缩是否会损害控制流感所需的免疫反应。胸腺选择和 T 细胞对流感病毒免疫的贡献。