Rise above the stress – ER stress and autophagy enhance the release of hepatitis B virus sub particles

Hepatology ◽  
2021 ◽  
Author(s):  
Lei Wei ◽  
Alexander Ploss
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Er Stress ◽  
B Virus

scholarly journals Activation of Hepatitis B Virus S Promoter by a Cell Type-Restricted IRE1-Dependent Pathway Induced by Endoplasmic Reticulum Stress

2005 ◽  
Vol 25 (17) ◽  
pp. 7522-7533 ◽  
Author(s):  
Zhi-Ming Huang ◽  
Thomas Tan ◽  
Hiderou Yoshida ◽  
Kazutoshi Mori ◽  
Yanjun Ma ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Er Stress ◽  
Transcriptional Activation ◽  
Active Form ◽  
Dominant Negative ◽  
Dependent Manner ◽  
Cell Type ◽  
B Virus

ABSTRACT IRE1-alpha is an integral membrane protein of the endoplasmic reticulum (ER) that is a key sensor in the cellular transcriptional response to stress in the ER. Upon induction of ER stress, IRE1-alpha is activated, resulting in the synthesis of the active form of the transcription factor XBP1 via IRE1-mediated splicing of its mRNA. In this report, we have examined the role of IRE1-alpha and XBP1 in activation of the hepatitis B virus S promoter by ER stress. Cotransfection experiments revealed that overexpression of either IRE1-alpha or XBP1 activated this promoter. Conversely, cotransfected dominant-negative IRE1-alpha or small interfering RNA directed against XBP1 decreased the activation of the S promoter by ER stress, confirming an important role for the IRE1-alpha/XBP1 signaling pathway in activation of the S promoter. However, XBP1 does not bind directly to the S promoter; rather, a novel S promoter-binding complex that does not contain XBP1 is induced in cells undergoing ER stress in an XBP1-dependent manner. This complex, as well as transcriptional activation of the S promoter, is induced by ER stress in hepatocytes but not in fibroblasts, despite the presence of active XBP1 in the latter. Thus, the hepatitis B virus S promoter responds to a novel, cell type-restricted transcriptional pathway downstream of IRE1-alpha and XBP1.

scholarly journals Pre-S2 Mutant-Induced Mammalian Target of Rapamycin Signal Pathways as Potential Therapeutic Targets for Hepatitis B Virus-Associated Hepatocellular Carcinoma

2017 ◽  
Vol 26 (3) ◽  
pp. 429-438 ◽  
Author(s):  
Chiao-Fang Teng ◽  
Han-Chieh Wu ◽  
Woei-Cherng Shyu ◽  
Long-Bin Jeng ◽  
Ih-Jen Su
Keyword(s):  
Hepatocellular Carcinoma ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Er Stress ◽  
Mammalian Target Of Rapamycin ◽  
Hbv Infection ◽  
Target Of Rapamycin ◽  
Signal Pathways ◽  
Type Ii ◽  
B Virus

Chronic hepatitis B virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC). Pre-S2 mutant represents an HBV oncoprotein that is accumulated in the endoplasmic reticulum (ER) and manifests as type II ground glass hepatocytes (GGHs). Pre-S2 mutant can induce ER stress and initiate multiple ER stress-dependent or -independent cellular signal pathways, leading to growth advantage of type II GGH. Importantly, the mammalian target of rapamycin (mTOR) signal pathways are consistently activated throughout the liver tumorigenesis in pre-S2 mutant transgenic mice and in human HCC tissues, leading to hepatocyte proliferation, metabolic disorders, and HCC tumorigenesis. In this review, we summarize the pre-S2 mutant-induced mTOR signal pathways and its implications in HBV-related HCC tumorigenesis. Clinically, the presence of pre-S2 mutant exhibits a high resistance to antiviral treatment and carries a high risk of HCC development in patients with chronic HBV infection. Targeting at pre-S2 mutant-induced mTOR signal pathways may thus provide potential strategies for the prevention or therapy of HBV-associated HCC.

scholarly journals Hepatocyte Endoplasmic Reticulum Stress Inhibits Hepatitis B Virus Secretion and Delays Intracellular Hepatitis B Virus Clearance After Entecavir Treatment

2021 ◽  
Vol 7 ◽  
Author(s):  
Huan Chen ◽  
Maoyuan Mu ◽  
Qichuan Liu ◽  
Han Hu ◽  
Caiyun Tian ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Er Stress ◽  
Western Blotting ◽  
Hbv Dna ◽  
Translation Initiation Factor ◽  
Enzyme Linked Immunosorbent Assay ◽  
Hbv Replication ◽  
B Virus

Background: The aim of this study was to explore the effects of endoplasmic reticulum (ER) stress on hepatitis B virus (HBV) replication and the antiviral effect of entecavir (ETV).Methods: Thapsigargin (TG) and stearic acid (SA) were used to induce ER stress in HepG2.2.15 cells and HepAD38 cells that contained an integrated HBV genome, while ETV was used to inhibit HBV replication. The expression levels of glucose-regulated protein 78 (GRP78) and phosphorylated eukaryotic translation initiation factor 2 subunit alpha (p-eIF2α) were measured by western blotting. Intracellular HBV DNA was determined by qPCR; HBsAg by western blotting; HBV RNA by real-time RT-qPCR; HBsAg and HBeAg in supernatants by enzyme-linked immunosorbent assay (ELISA); and HBV DNA in supernatants by qPCR.Results: TG and SA induced ER stress in HepG2.2.15 cells and HepAD38 cells from 12 to 48 h post treatment. However, 4-phenylbutyric acid (PBA) partly alleviated the TG-induced ER stress. Moreover, TG inhibited HBsAg, HBeAg, and HBV DNA secretion from 12 to 48 h, while different concentrations of SA inhibited HBsAg and HBV DNA secretion at 48 h. TG promoted intracellular HBV DNA and HBsAg accumulation and the transcription of the HBV 3.5-kb mRNA and S mRNA. PBA treatment restored the secretion of HBsAg and HBV DNA. Finally, ER stress accelerated extracellular HBV DNA clearance but delayed intracellular HBV DNA clearance after ETV treatment.Conclusions: Hepatocyte ER stress promoted intracellular HBV DNA and HBsAg accumulation by inhibiting their secretion. Our study also suggested that hepatocyte ER stress delayed intracellular HBV DNA clearance after ETV treatment.

Hepatitis B virus small envelope protein promotes HCC angiogenesis via ER stress signaling to upregulate VEGFA expression

2021 ◽  
Author(s):  
Shu-Xiang Wu ◽  
Shuang-Shuang Ye ◽  
Yu-Xiang Hong ◽  
Yan Chen ◽  
Biao Wang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Endoplasmic Reticulum ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Er Stress ◽  
Viral Protein ◽  
Unfolded Protein ◽  
B Virus ◽  
Protein Response ◽  
Hcc Cells

Hepatocellular carcinoma (HCC) is a hypervascular tumor and accumulating evidence has indicated that stimulation of angiogenesis by HBV may contribute to HCC malignancy. The small protein of hepatitis B virus surface antigen (HBsAg), SHBs, is the most abundant HBV viral protein and has a close clinical association with HCC, however, whether SHBs contributes to HCC angiogenesis remains unknown. This study reports that forced expression of SHBs in HCC cells promoted xenograft tumor growth and increased the microvessel density (MVD) within the tumors. Consistently, HBsAg was also positively correlated with MVD count in HCC patients’ specimens. The conditioned media from the SHBs-transfected HCC cells increased the capillary tube formation and migration of human umbilical vein endothelial cells (HUVECs). Intriguingly, overexpression of SHBs increased VEGFA expression at both mRNA and protein levels. A higher VEGFA expression level was also observed in the xenograft tumors transplanted with SHBs-expressing HCC cells and in HBsAg-positive HCC tumor tissues as compared to their negative controls. As expected, in the culture supernatants, the secretion of VEGFA was also significantly enhanced from HCC cells expressing SHBs, which promoted HUVECs migration and vessel formation. Furthermore, all the three unfolded protein response (UPR) sensors IRE1α, PERK and ATF6 associated with endoplasmic reticulum (ER) stress were found activated in the SHBs-expressing cells and correlated with VEGFA protein expression and secretion. Taken together, these results suggest an important role of SHBs in HCC angiogenesis and may highlight a potential target for preventive and therapeutic intervention of HBV-related HCC and its malignant progression. IMPORTANCE Chronic hepatitis B virus infection is one of the important risk factors for the development and progression of hepatocellular carcinoma (HCC). HCC is characteristic of hypervascularization even at early phases of the disease due to overexpression of angiogenic factors like vascular endothelial growth factor-A (VEGFA). However, a detailed mechanism in the HBV-induced angiogenesis remains to be established. In this study, we demonstrate for the first time that the most abundant HBV viral protein, i.e. small surface antigens (SHBs) can enhance the angiogenic capacity of HCC cells by upregulation of VEGFA expression both in vitro and in vivo . Mechanistically, SHBs induced endoplasmic reticulum (ER) stress which consequently activated unfolded protein response (UPR) signaling to increase VEGFA expression and secretion. This study suggests that SHBs plays an important pro-angiogenic role in HBV-associated HCC and may represent a potential target for anti-angiogenic therapy in the HCC.

scholarly journals Regulation of Molecular Chaperone GRP78 by Hepatitis B Virus: Control of Viral Replication and Cell Survival

2019 ◽  
Vol 40 (3) ◽  
Author(s):  
Wangqin Shu ◽  
Zhiwei Guo ◽  
Lijie Li ◽  
Zhiqi Xiong ◽  
Ziyu Wang ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Er Stress ◽  
Molecular Chaperones ◽  
Inhibitory Effect ◽  
Hbv Infection ◽  
Loss Of Function ◽  
B Virus ◽  
Underlying Mechanisms ◽  
Novel Therapeutic Strategies

ABSTRACT Chronic hepatitis B (CHB) remains a global health problem, carrying a high risk for progression into cirrhosis and liver failure. Molecular chaperones are involved in diverse pathophysiological processes including viral infection. However, the role of molecular chaperones in hepatitis B virus (HBV) infection and its underlying mechanisms remain unclear. Here, we identified GRP78 as one of the molecular chaperones most strongly induced by HBV in human hepatocytes. Gain- and loss-of-function analyses demonstrated that GRP78 exerted an inhibitory effect on HBV transcription and replication. Further study showed that GRP78 was involved in the activation of AKT/mTOR signaling in hepatocytes, which contributed to GRP78-mediated inhibition of HBV. Of note, HBV-upregulated GRP78 was found to play a crucial role in maintaining the survival of hepatocytes via facilitating a mild endoplasmic reticulum (ER) stress. Together, our findings suggest that HBV may sacrifice part of its replication for establishing a persistent infection through induction of GRP78, a master ER stress regulator. Targeting GRP78 may help develop to design novel therapeutic strategies against chronic HBV infection and the associated hepatocellular carcinoma.

scholarly journals Role of Hepatitis B Virus Large Surface Protein in Promoting Activation of Nuclear SREBPs via ER Stress: Implications for Hepatocellular Carcinoma

2019 ◽  
Vol 11 (2) ◽  
pp. 13
Author(s):  
Subir Ghosh
Keyword(s):  
Hepatocellular Carcinoma ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Er Stress ◽  
Regulatory Element ◽  
Regulatory Elements ◽  
Protein Activity ◽  
Atp Citrate Lyase ◽  
Citrate Lyase ◽  
B Virus

One of the most common fatal malignancies in the world is Hepatocellular carcinoma (HCC) and hepatitis B virus (HBV) infection has been identified as a leading risk factor for HCC. Studies have suggested that during infection the large surface viral protein of HBV (LS protein) is targeted to the endoplasmic reticulum (ER) of the host liver cell, where its accumulation causes ER stress leading to HCC. The LS protein is also believed to stimulate the lipogenic activity of the ATP citrate lyase (ACL) enzyme, leading to excessive synthesis of lipids required for the rapidly dividing liver tumor cell. Here, I propose a hypothesis linking viral LS protein-induced ER stress to generation of the mature transcriptionally active nuclear form of sterol regulatory element-binding protein (nSREBP). nSREBP translocates to the nucleus and binds to sterol regulatory elements (SRE) present in the ATP citrate lyase (ACL) gene promoter, thereby elevating ACL transcription levels and overproduction of the ACL enzyme protein. Inhibition of LS protein activity in the ER may provide a therapeutic strategy in treating HBV induced HCC.

scholarly journals Naturally Occurring Hepatitis B Virus Mutations Leading to Endoplasmic Reticulum Stress and Their Contribution to the Progression of Hepatocellular Carcinoma

2019 ◽  
Vol 20 (3) ◽  
pp. 597 ◽  
Author(s):  
Yu-Min Choi ◽  
So-Young Lee ◽  
Bum-Joon Kim
Keyword(s):  
Hepatocellular Carcinoma ◽  
Endoplasmic Reticulum ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Er Stress ◽  
Clinical Outcomes ◽  
Hbv Infection ◽  
Stress Induction ◽  
Naturally Occurring ◽  
B Virus

Hepatitis B virus (HBV) infection is a global health problem that causes a wide range of pathological outcomes, including cirrhosis and hepatocellular carcinoma (HCC). Endoplasmic reticulum (ER) stress induction by HBV infection has been implicated in liver carcinogenesis and disease progression with chronic inflammation via enhanced inflammation, oxidative stress-mediated DNA damage, and hepatocyte proliferation. In the natural course of HBV infection, the accumulation of naturally occurring mutations in the HBV genome can generate several mutant types of HBV-encoded proteins, including three different proteins in the S ORF (SHBs, MHBs, and LHBs) and HBcAg in the C ORF, which could contribute to enhanced ER stress in infected hepatocytes mainly via increased ER accumulation of mutant proteins. However, it seems that there may be distinct capacity and pathway in ER stress-induction and distinct resulting clinical outcomes between HBV variants. In addition, the role of HBxAg mutations in ER stress remains unknown. However, it has been reported that HBxAg itself could exert ER stress in infected cells, resulting in HCC generation in chronic HBV patients. To date, review papers regarding ER stress-mediated HBV mutation have been limited into a specific mutation type: preS2 deletion. So, in this review, we will discuss details about various mutation types in all four regions of the HBV genome (preS1, preS2, S, and C) related to ER stress and their distinct ER stress mechanisms and clinical outcomes in terms of mutation types.

scholarly journals Induction of hepatitis D virus large antigen translocation to the cytoplasm by hepatitis B virus surface antigens correlates with endoplasmic reticulum stress and NF-κB activation

2006 ◽  
Vol 87 (6) ◽  
pp. 1715-1723 ◽  
Author(s):  
I-Cheng Huang ◽  
Chia-Ying Chien ◽  
Chi-Ruei Huang ◽  
Szecheng J. Lo
Keyword(s):  
Endoplasmic Reticulum ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Er Stress ◽  
Nuclear Export ◽  
Signal Molecules ◽  
Hepatitis D ◽  
Small Form ◽  
Hepatitis D Virus ◽  
B Virus

It is known that hepatitis D virus (HDV) requires hepatitis B virus (HBV) for supplying envelope proteins (HBsAgs) to produce mature virions, and the HDV large antigen (LDAg) is responsible for interacting with HBsAgs. However, the signal molecules involved in the cross-talk between HBsAgs and LDAg have never been reported. It has been previously demonstrated that the small form of HBsAg can facilitate the translocation of HDV large antigen green fluorescent protein (GFP) fusion protein (GFP–LD) from the nucleus to the cytoplasm. In this study, it was confirmed that the small form of HBsAg can facilitate both GFP–LD and authentic LDAg for nuclear export. It was also shown that the three forms of HBsAgs (large, middle and small) induced various rates (from 35.4 to 57.2 %) of GFP–LD nuclear export. Since HBsAgs are localized inside the endoplasmic reticulum (ER), this suggests that ER stress possibly initiates the signal for inducing LDAg translocation. This supposition is supported by results that show that around 9 % of cells appear with GFP–LD in the cytoplasm after treatment with the ER stress inducers, brefeldin A (BFA) and tunicamycin, in the absence of HBsAg. Western blot and immunofluorescence microscopy results further showed that the activation of NF-κB is linked to the ER stress that induces GFP–LD translocation. Combining this with results showing that tumour necrosis factor alpha (TNF-α) can also induce GFP–LD translocation, it was concluded that LDAg translocation correlates with ER stress and activation of NF-κB. Nevertheless, TNF-α-induced GFP–LD translocation was independent of new protein synthesis, suggesting that a post-translational event occurs to GFP–LD to allow translocation.

scholarly journals Hepatitis B Virus Middle Protein Enhances IL-6 Production via p38 MAPK/NF-κB Pathways in an ER Stress-Dependent Manner

PLoS ONE ◽  
2016 ◽  
Vol 11 (7) ◽  
pp. e0159089 ◽  
Author(s):  
Yang-Xia Li ◽  
Yan-Li Ren ◽  
Hai-Jing Fu ◽  
Ling Zou ◽  
Ying Yang ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Er Stress ◽  
P38 Mapk ◽  
Dependent Manner ◽  
B Virus ◽  
Stress Dependent
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