Regulation of the Cell Death Program by DFNA5

摘要 细胞凋亡和细胞凋亡在生长、存活、稳态和先天免疫中起着关键的生理作用 所有的哺乳动物。这些通路的失调可能导致许多疾病，包括自身免疫性疾病， 炎症、动脉粥样硬化和恶性疾病。虽然细胞凋亡是一种免疫学上的“沉默”形式， 细胞凋亡是由效应子半胱天冬酶3、6和7的激活引起的程序性细胞死亡， 通过激活炎性半胱天冬酶1、4和 5在人类这些炎性半胱天冬酶切割gasdermin蛋白，GSDMD，产生一个孔- 形成N-末端片段，使质膜透化，导致细胞肿胀，渗透性 细胞溶解和细胞内内容物渗漏。如果凋亡细胞没有被清除，如图中所示， 在体外培养条件下或体内吞噬功能受损的条件下，它们进展为溶解性和炎性细胞， 称为继发性坏死。继发性坏死与焦亡有几个共同特征， 质膜透化、肿胀和溶解，因此它可能代表一种形式的焦亡。 事实上，我们最近发现，活化的半胱天冬酶-3切割gasdermin相关蛋白DFNA 5， 细胞凋亡以产生坏死的DFNA 5-N片段，其靶向质膜以使其透化， 引起继发性坏死/焦亡。有趣的是，与WT细胞不同，DFNA 5缺陷细胞不聚集 并膨胀，但广泛地分裂成小的凋亡小体，这表明DFNA 5是细胞凋亡的调节因子。 凋亡过程中的解体。由于细胞凋亡过程中的细胞解体可能会影响死亡细胞的清除 通过吞噬细胞，我们提出了一个假设，即细胞凋亡过程中DFNA 5的切割诱导了细胞内的孔， 质膜释放“找到我”和其他吞噬细胞激活信号，以清除凋亡细胞， 使凋亡细胞分解成小的凋亡小体。在本申请中，我们提出了 为了进一步了解DFNA 5在体内的生理功能，及其在自身免疫中的作用， 炎症和先天免疫。我们将研究DFNA 5缺陷小鼠中凋亡细胞的清除 并进一步评估DFNA 5缺乏在发展中的病理生理学后果， 自身免疫我们还将描述DFNA 5的另一个新功能，该功能参与调节细胞的生长。 线粒体凋亡途径以及这种活性如何影响细胞增殖和对凋亡的敏感性 刺激。最后，我们将研究DFNA 5在宿主对病毒病原体的先天免疫中的作用， 感染性休克和炎症引起的恶性肿瘤。这项研究的结果应该对以下方面产生很大影响： 增加我们对细胞凋亡过程中激活的信号通路的理解 导致细胞透化及其对组织稳态、自身免疫和炎症的影响 疾病

Abstract Apoptosis and pyroptosis play key physiological roles in growth, survival, homeostasis and innate immunity of all mammals. Disregulation of these pathways could lead to many diseases including autoimmune, inflammatory, atherosclerotic and malignant diseases. While apoptosis is an immunologically “silent” form of programmed cell death executed by activation of the effector caspases 3, 6 and 7, pyroptosis is an inflammatory form of programmed cell death executed by activation of the inflammatory caspases 1, 4, and 5 in humans. These inflammatory caspases cleave the gasdermin protein, GSDMD, to generate a pore- forming N-terminal fragment that permeabilizes the plasma membrane leading, to cellular swelling, osmotic cell lysis and leakage of intracellular contents. If apoptotic cells are not scavenged, such as seen under in vitro culture conditions or conditions of impaired phagocytosis in vivo, they progress to a lytic and inflammatory phase called secondary necrosis. Secondary necrosis shares several features with pyroptosis including plasma membrane permeabilization, swelling, and lysis, and therefore it could represent a form of pyroptosis. Indeed, we discovered recently that activated caspase-3 cleaves the gasdermin-related protein DFNA5 during apoptosis to generate a necrotic DFNA5-N fragment that targets the plasma membrane to permeabilize it and induce secondary necrosis/pyroptosis. Interestingly, unlike WT cells, DFNA5-deficient cells do not roundup and swell, but extensively fragment into small apoptotic bodies suggesting that DFNA5 is a regulator of cellular disassembly during apoptosis. As cellular disassembly during apoptosis may impact clearance of dying cells by phagocytes, we propose to test the hypothesis that DFNA5 cleavage during apoptosis induces pores in the plasma membrane to release “find me” and other phagocyte activation signals to clear apoptotic cells and to temper down disassembly of apoptotic cells into small apoptotic bodies. In this application we propose aims to gain further insight into the physiological function of DFNA5 in vivo, and its role in autoimmunity, inflammation and innate immunity. We will study the clearance of apoptotic cells in DFNA5-deficient mice and further assess the pathophysiological consequences of DFNA5 deficiency in the development of autoimmunity. We will also characterize another novel function of DFNA5 involved in the regulation of the mitochondrial apoptotic pathway and how this activity might impact cell proliferation and sensitivity to apoptotic stimuli. Finally, we will investigate the role of DFNA5 in the host innate immunity against viral pathogens, septic shock and inflammation-induced malignancy. Results from this research should have a high impact on the field and increase our understanding of the signaling pathways activated during the apoptotic program leading to cell permeabilization and their impact on tissue homeostasis, and autoimmune and inflammatory diseases.