ER stress-related molecules induced by Hantaan virus infection in differentiated THP-1 cells

摘要

Endoplasmic reticulum stress (ER stress) can be induced by virus infection. In this part, we explored whether Hantaan virus (HTNV) infection could induce ER stress in differentiated THP-1 (dTHP-1) cells. It showed that the mRNA and protein levels of ER stress-related 78 kDa glucose-regulated protein (GRP78, HSPA5) and mRNA levels of X box-binding protein 1 (XBP-1), activating transcription factor 6(ATF6) and PKR-like ER kinase (PERK) after HTNV infection, were significantly higher than that in uninfected control group. However, the mRNA levels of C/EBP homologous protein (CHOP), glucose-regulated protein 94 (GRP94, HSPC4), and inositol-requiring enzyme1 (IRE1) were not significantly different between the infected group and the untreated group in 2 h after virus infection. It is unusual in activating GRP78 but not GRP94. Meanwhile, dTHP-1 cells infected with HTNV at 12 h did not show obvious apoptosis. These results indicated that the HTNV infection could induce the unfolded protein response (UPR) in dTHP-1 cells, without directly leading to cell apoptosis during 12 h after virus infection. Keywords: Hantaan virus (HTNV), Hemorrhagic fever with renal syndrome (HFRS), Endoplasmic reticulum stress (ER stress), 78 kDa glucose-regulated protein (GRP78, HSPA5), dTHP-1IntroductionEndoplasmic reticulum stress (ER stress) is the stress response to the accumulation of a large number of unfolded proteins in the endoplasmic reticulum. Cells respond to ER stress through unfolded protein reaction, autophagy, and apoptosis (Mehrbod et al. 2019 ). Previous studies have found that many viruses cause ER stress after they infect cells, such as hepatitis B virus (HBV), hepatitis C virus, human immunodeficiency virus (HIV), rhinovirus, and Newcastle disease virus (Bhoola and Kramvis 2017; Medvedev et al. 2017; Fan and He 2016; Liu et al. 2017; Bu et al. 2016; Sepulveda-Salinas and Ramos-Castaneda 2017; Johnston and McCormick 2020). However, due to the different types of viruses, time of infection, and number of cells, the fate of the cells is different. For example, the expression of 78 kDa glucose-regulated protein (GRP78) in HepG2 cells induced by HBV infection inhibited the replication of HBV via the interferon beta1-2 ' ,5 ' -oligoadenylate synthetase-RNase L pathway to balance the stress caused by HBV to protect the cells. Induction of hepatic GRP78 may provide a novel therapeutic approach in treating HBV infection (Ma et al. 2009). Triggering the unfolded protein response by 2-deoxy-D-glucose (2-DG) inhibits porcine epidemic diarrhea virus propagation. The result supports the therapeutic potential of using 2-DG or glucose/mannose analogs to induce the UPR to block virus replication (Wang et al. 2014). The mechanism of HBV inhibition by the compound p-hydroxyacetophenone (PHAP) might involve the regulation of viral surface gene expression and may block virion secretion by interference with the ER stress signaling pathway. The 2.4 kb preS RNA of viral surface gene increased significantly relative to the 2.1 kb S RNA with PHAP. Promoter activity analysis demonstrated that PHAP had a potent effect on augmenting the viral preS promoter activity. The subsequent increase in the large surface protein induced endoplasmic reticulum (ER) stress (Huang et al. 2014). Moreover, the influenza A virus and Crimean-Congo hemorrhagic fever virus (CCHFV) could cause hepatocyte cell apoptosis by endoplasmic reticulum and mitochondrial pathways (Roberson et al. 2012; Rodrigues et al. 2012). The results can explain the pathogenesis of the both viruses .Hantaan virus (HTNV) is a kind of virus belonging to the Hantavirus (HTV) genus of Bunyaviridae family (Mir 2010; Schmaljohn and Dalrymple 1983). Hemorrhagic fever with renal syndrome (HFRS) caused by Hantavirus (HTV) is an acute infectious disease characterized by fever, hemorrhage, and acute renal impairment (Jonsson et al. 2010). After HTV invades the human body, it directly acts on the whole body capillaries and small blood vessels, causing extensive vascular wall damage (Gorbunova et al. 2013; Gavrilovskaya et al. 2012; Jiang et al. 2016; Hepojoki et al. 2014). Li XD et al. have reported that Tula hantavirus could?trigger pro-apoptotic signals of ER stress in Vero E6 cells (Li et al. 2005). Studies showed that HTNV infection could induce TNF-related apoptosis-inducing ligand (TRAIL) expression in primary human umbilical vein endothelial cells (HUVECs) and sensitize host cells toward TRAIL-mediated apoptosis (Chen et al. 2020). Nevertheless, Hardestam et al. argued that hantaviruses coundn’t?induce apoptosis in confluent Vero-E6 and A549 cells and may induce a very low level of apoptosis in dividing cells (Hardestam et al. 2005). Ontiveros et al. showed that the cellular apoptotic responses were?inhibited by exogenous-expressing HTNV N protein in Hela cells (Ontiveros et al. 2010). However, after HTNV infects mononuclear macrophages, the effect of ER stress and subsequent cell fate are not c