Programmed necrosis in Immune Responses

描述(申请人提供)：程序性坏死导致的细胞死亡在形态和机制上不同于细胞凋亡。坏死细胞迅速失去其质膜的完整性。内源性“危险信号”的释放会引发炎症，并可能影响先天免疫和获得性免疫反应的质量和大小。从机制上讲，当半胱氨酸酶被抑制时，例如在感染编码半胱氨酸天冬氨酸酶抑制剂的病毒时，程序性坏死是最佳的诱导方式。程序性坏死的作用通过识别针对程序性坏死的病毒抑制物而得到支持，例如某些病毒翻转(FLICE(caspase-8)样抑制蛋白)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很重要，但调节程序性坏死的分子途径相对来说还不清楚。我们试图通过筛选一个小干扰RNA(SiRNA)的激酶基因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，它们是肿瘤坏死因子诱导的程序性坏死的关键调节因子。在这个应用中，我们将研究调控RIP1/RIP3依赖的程序性坏死的分子机制。具体地说，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，我们还将研究RIP1和RIP3激活程序性坏死下游效应阶段的机制。具体地说，我们将研究促坏死的RIP1-RIP3复合体如何调节线粒体通透性转换孔(MPTP)的功能。最后，我们将以痘苗病毒感染为模型，评估RIP3依赖的程序性坏死的生理学相关性。具体地说，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。 公共卫生相关性：细胞坏死导致的死亡会引起炎症，并可能极大地影响免疫反应的质量。在这项建议中，我们将研究通过坏死控制细胞死亡的分子信号，并评估它如何影响针对病毒感染的免疫反应的效率。这些研究将使我们能够更好地了解控制炎症的信号，并制定在生理和病理条件下控制炎症的策略。

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.