McRae Steven, Iqbal Jawed, Sarkar-Dutta Mehuli, Lane Samantha, Nagaraj Abhiram, Ali Naushad, Waris Gulam
From the Department of Microbiology and Immunology, H. M. Bligh Cancer Research Laboratories, Rosalind Franklin University of Medicine and Science, Chicago Medical School, North Chicago, Illinois 60064 and.
the Department of Medicine, Section of Digestive Diseases and Nutrition, University of Oklahoma, Oklahoma City, Oklahoma 73104.
J Biol Chem. 2016 Feb 12;291(7):3254-67. doi: 10.1074/jbc.M115.694059. Epub 2015 Dec 23.
Hepatitis C virus (HCV) relies on host lipids and lipid droplets for replication and morphogenesis. The accumulation of lipid droplets in infected hepatocytes manifests as hepatosteatosis, a common pathology observed in chronic hepatitis C patients. One way by which HCV promotes the accumulation of intracellular lipids is through enhancing de novo lipogenesis by activating the sterol regulatory element-binding proteins (SREBPs). In general, activation of SREBPs occurs during cholesterol depletion. Interestingly, during HCV infection, the activation of SREBPs occurs under normal cholesterol levels, but the underlying mechanisms are still elusive. Our previous study has demonstrated the activation of the inflammasome complex in HCV-infected human hepatoma cells. In this study, we elucidate the potential link between chronic hepatitis C-associated inflammation and alteration of lipid homeostasis in infected cells. Our results reveal that the HCV-activated NLRP3 inflammasome is required for the up-regulation of lipogenic genes such as 3-hydroxy-3-methylglutaryl-coenzyme A synthase, fatty acid synthase, and stearoyl-CoA desaturase. Using pharmacological inhibitors and siRNA against the inflammasome components (NLRP3, apoptosis-associated speck-like protein containing a CARD, and caspase-1), we further show that the activation of the NLRP3 inflammasome plays a critical role in lipid droplet formation. NLRP3 inflammasome activation in HCV-infected cells enables caspase-1-mediated degradation of insulin-induced gene proteins. This subsequently leads to the transport of the SREBP cleavage-activating protein·SREBP complex from the endoplasmic reticulum to the Golgi, followed by proteolytic activation of SREBPs by S1P and S2P in the Golgi. Typically, inflammasome activation leads to viral clearance. Paradoxically, here we demonstrate how HCV exploits the NLRP3 inflammasome to activate SREBPs and host lipid metabolism, leading to liver disease pathogenesis associated with chronic HCV.
丙型肝炎病毒(HCV)依靠宿主脂质和脂滴进行复制和形态发生。感染的肝细胞中脂滴的积累表现为肝脂肪变性,这是在慢性丙型肝炎患者中观察到的一种常见病理现象。HCV促进细胞内脂质积累的一种方式是通过激活固醇调节元件结合蛋白(SREBPs)来增强从头脂肪生成。一般来说,SREBPs的激活发生在胆固醇耗竭期间。有趣的是,在HCV感染期间,SREBPs的激活发生在正常胆固醇水平下,但其潜在机制仍然难以捉摸。我们之前的研究已经证明了HCV感染的人肝癌细胞中炎性小体复合物的激活。在本研究中,我们阐明了慢性丙型肝炎相关炎症与感染细胞中脂质稳态改变之间的潜在联系。我们的结果表明,HCV激活的NLRP3炎性小体是上调诸如3-羟基-3-甲基戊二酰辅酶A合酶、脂肪酸合酶和硬脂酰辅酶A去饱和酶等脂肪生成基因所必需的。使用针对炎性小体成分(NLRP3、含CARD的凋亡相关斑点样蛋白和半胱天冬酶-1)的药理抑制剂和小干扰RNA,我们进一步表明NLRP3炎性小体的激活在脂滴形成中起关键作用。HCV感染细胞中NLRP3炎性小体的激活使得半胱天冬酶-1介导胰岛素诱导基因蛋白的降解。这随后导致SREBP裂解激活蛋白·SREBP复合物从内质网转运到高尔基体,随后在高尔基体中由S1P和S2P对SREBPs进行蛋白水解激活。通常,炎性小体激活会导致病毒清除。矛盾的是,我们在此证明了HCV如何利用NLRP3炎性小体激活SREBPs和宿主脂质代谢,导致与慢性HCV相关的肝脏疾病发病机制。
Microbiol Spectr. 2021-9-3
J Gen Virol. 2011-10-12
Front Pharmacol. 2024-7-30
Acta Pharmacol Sin. 2024-3
Front Cell Infect Microbiol. 2023
Front Immunol. 2020
Lipids Health Dis. 2020-3-6
Lipids Health Dis. 2019-11-4
Aging Dis. 2019-10-1
Clin Exp Hepatol. 2019-5
Trends Microbiol. 2014-10-22
PLoS One. 2014-1-6
Front Cell Infect Microbiol. 2013-11-26