Programmed necrosis in Immune Responses

描述（申请人提供）：程序性坏死细胞死亡在形态和机制上不同于细胞凋亡。坏死细胞迅速失去质膜的完整性。内源性“危险信号”的释放会引发炎症，并影响先天和适应性免疫反应的质量和大小。从机制上讲，当半胱天冬酶被抑制时，如在编码半胱天冬酶抑制剂的病毒感染期间，最佳地诱导程序性坏死。程序性坏死的作用被确定为针对程序性坏死的病毒抑制剂，如某些病毒FLIPs （FLICE（caspase-8）样抑制剂蛋白）和小鼠巨细胞病毒（MCMV） M45蛋白。尽管程序性坏死在炎症和抗病毒免疫中的重要性，但调控程序性坏死的分子途径相对不明确。我们试图通过筛选激酶基因的小干扰RNA （siRNA）文库来了解程序性坏死的分子调控。从我们的筛选中，我们确定了受体相互作用蛋白家族的两个成员，RIP1和RIP3，作为tnf诱导的程序性坏死的关键调节因子。在本应用中，我们将研究调节RIP1/ rip3依赖性程序性坏死的分子机制。具体来说，我们将研究蛋白质磷酸化和泛素化在调节RIP1和RIP3活性中的作用。此外，我们将研究RIP1和RIP3激活程序性坏死下游效应期的机制。具体来说，我们将研究促坏死RIP1-RIP3复合体如何调节线粒体通透性过渡孔（mPTP）的功能。最后，我们将以牛痘病毒感染为模型，评估rip3依赖性程序性坏死的生理相关性。具体来说，我们将研究抑制rip3缺陷小鼠的程序性坏死如何影响病毒诱导的坏死、炎症和随后的适应性免疫反应。

DESCRIPTION (provided by applicant): Cell death by programmed necrosis is distinct from apoptosis in morphology and mechanism. Necrotic cells rapidly lose their plasma membrane integrity. The release of endogenous "danger signals" trigger inflammation and can impact the quality and magnitude of innate and adaptive immune responses. Mechanistically, programmed necrosis is optimally induced when caspases are inhibited, such as that during infections with viruses that encode caspase inhibitors. A role for programmed necrosis is bolstered by the identification of viral inhibitors against programmed necrosis, such as certain viral FLIPs (FLICE(caspase-8)-like inhibitor proteins) and the mouse cytomegalovirus (MCMV) M45 protein. Despite the importance of programmed necrosis in inflammation and anti-viral immunity, the molecular pathway that regulates programmed necrosis is relatively undefined. We sought to understand the molecular regulation of programmed necrosis by screening a small interference RNA (siRNA) library of kinase genes. From our screen, we identified two members of the receptor interacting protein family, RIP1 and RIP3, as crucial regulators for TNF-induced programmed necrosis. In this application, we will examine the molecular mechanisms that regulate RIP1/RIP3-dependent programmed necrosis. Specifically, we will examine the role of protein phosphorylation and ubiquitination in regulating RIP1 and RIP3 activity. In addition, we will examine the mechanisms by which RIP1 and RIP3 activates the downstream effector phase of programmed necrosis. Specifically, we will examine how the pro-necrotic RIP1-RIP3 complex modulates the function of the mitochondria permeability transition pore (mPTP). Finally, we will evaluate the physiological relevance of RIP3-dependent programmed necrosis using vaccinia virus infection as a model. Specifically, we will examine how inhibition of programmed necrosis in RIP3-deficient mice affects virus-induced necrosis, inflammation, and subsequent adaptive immune responses. PUBLIC HEALTH RELEVANCE: Cell death by necrosis causes inflammation and can greatly impact the quality of an immune response. In this proposal, we will study the molecular signals that control cell death by necrosis and evaluate how it impacts the efficiency of immune responses against virus infections. These studies will allow us to better understand the signals that control inflammation and to develop strategies to control it in physiological and pathological conditions.