bims-mevinf 2023-06-04 papers

Issue of 2023‒06‒04
six papers selected by
Alexander Ivanov
Engelhardt Institute of Molecular Biology

Virol J. 2023 May 31. 20(1): 108

2-Deoxy-D-glucose inhibits lymphocytic choriomeningitis virus propagation by targeting glycoprotein N-glycosylation.

Lucia Baďurová, Katarína Polčicová, Božena Omasta, Ingrid Ovečková, Eva Kocianová, Jana Tomášková.

BACKGROUND: Increased glucose uptake and utilization via aerobic glycolysis are among the most prominent hallmarks of tumor cell metabolism. Accumulating evidence suggests that similar metabolic changes are also triggered in many virus-infected cells. Viral propagation, like highly proliferative tumor cells, increases the demand for energy and macromolecular synthesis, leading to high bioenergetic and biosynthetic requirements. Although significant progress has been made in understanding the metabolic changes induced by viruses, the interaction between host cell metabolism and arenavirus infection remains unclear. Our study sheds light on these processes during lymphocytic choriomeningitis virus (LCMV) infection, a model representative of the Arenaviridae family.METHODS: The impact of LCMV on glucose metabolism in MRC-5 cells was studied using reverse transcription-quantitative PCR and biochemical assays. A focus-forming assay and western blot analysis were used to determine the effects of glucose deficiency and glycolysis inhibition on the production of infectious LCMV particles.
RESULTS: Despite changes in the expression of glucose transporters and glycolytic enzymes, LCMV infection did not result in increased glucose uptake or lactate excretion. Accordingly, depriving LCMV-infected cells of extracellular glucose or inhibiting lactate production had no impact on viral propagation. However, treatment with the commonly used glycolytic inhibitor 2-deoxy-D-glucose (2-DG) profoundly reduced the production of infectious LCMV particles. This effect of 2-DG was further shown to be the result of suppressed N-linked glycosylation of the viral glycoprotein.
CONCLUSIONS: Although our results showed that the LCMV life cycle is not dependent on glucose supply or utilization, they did confirm the importance of N-glycosylation of LCMV GP-C. 2-DG potently reduces LCMV propagation not by disrupting glycolytic flux but by inhibiting N-linked protein glycosylation. These findings highlight the potential for developing new, targeted antiviral therapies that could be relevant to a wider range of arenaviruses.

Keywords: 2-Deoxy-D-glucose; Antiviral therapy; Arenavirus; Cell metabolism; Glycolysis; Glycoprotein; LCMV; N-linked glycosylation; Virus-host interaction

DOI: https://doi.org/10.1186/s12985-023-02082-3

Front Cell Infect Microbiol. 2023 ;13 1189417

Metabolomics in viral hepatitis: advances and review.

Jiajia Yang, Dawei Wang, Yuancheng Li, Hongmei Wang, Qiang Hu, Ying Wang.

Viral hepatitis is a major worldwide public health issue, affecting hundreds of millions of people and causing substantial morbidity and mortality. The majority of the worldwide burden of viral hepatitis is caused by five biologically unrelated hepatotropic viruses: hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis D virus (HDV), and hepatitis E virus (HEV). Metabolomics is an emerging technology that uses qualitative and quantitative analysis of easily accessible samples to provide information of the metabolic levels of biological systems and changes in metabolic and related regulatory pathways. Alterations in glucose, lipid, and amino acid levels are involved in glycolysis, the tricarboxylic acid cycle, the pentose phosphate pathway, and amino acid metabolism. These changes in metabolites and metabolic pathways are associated with the pathogenesis and medication mechanism of viral hepatitis and related diseases. Additionally, differential metabolites can be utilized as biomarkers for diagnosis, prognosis, and therapeutic responses. In this review, we present a thorough overview of developments in metabolomics for viral hepatitis.

Keywords: biomarkers; metabolomics; pathogenesis; treatment; viral hepatitis

DOI: https://doi.org/10.3389/fcimb.2023.1189417

Redox Biol. 2023 May 23. pii: S2213-2317(23)00153-2. [Epub ahead of print]63 102752

SARS-CoV-2 ORF3a sensitizes cells to ferroptosis via Keap1-NRF2 axis.

Lihong Liu, Jie Du, Sidi Yang, Birong Zheng, Jian Shen, Jiacheng Huang, Liu Cao, Siyao Huang, Xue Liu, Liping Guo, Chunmei Li, Changwen Ke, Xiaofang Peng, Deyin Guo, Hong Peng.

Viral infection-induced cell death has long been considered as a double-edged sword in the inhibition or exacerbation of viral infections. Patients with severe Coronavirus Disease 2019 (COVID-19) are characterized by multiple organ dysfunction syndrome and cytokine storm, which may result from SARS-CoV-2-induced cell death. Previous studies have observed enhanced ROS level and signs of ferroptosis in SARS-CoV-2 infected cells or specimens of patients with COVID-19, but the exact mechanism is not clear yet. Here, we find SARS-CoV-2 ORF3a sensitizes cells to ferroptosis via Keap1-NRF2 axis. SARS-CoV-2 ORF3a promotes the degradation of NRF2 through recruiting Keap1, thereby attenuating cellular resistance to oxidative stress and facilitated cells to ferroptotic cell death. Our study uncovers that SARS-CoV-2 ORF3a functions as a positive regulator of ferroptosis, which might explain SARS-CoV-2-induced damage in multiple organs in COVID-19 patients and imply the potential of ferroptosis inhibition in COVID-19 treatment.

Keywords: Ferroptosis; Keap1; NRF2; ORF3a; SARS-CoV-2

DOI: https://doi.org/10.1016/j.redox.2023.102752

J Virol. 2023 May 31. 97(5): e0036423

The Small GTPase Rab14 Regulates the Trafficking of Ceramide from Endoplasmic Reticulum to Golgi Apparatus and Facilitates Classical Swine Fever Virus Assembly.

Ya-Yun Liu, Ji Shan Bai, Chun-Chun Liu, Jiang-Fei Zhou, Jing Chen, Yan Cheng, Bin Zhou.

Classical swine fever virus (CSFV) is a highly pathogenic RNA virus belonging to the Flaviviridae family that can cause deadly classical swine fever (CSF) in pigs. However, the molecular details of virus replication in the host are still unclear. Our previous studies have reported that several Rab proteins mediate CSFV entry into host cells, but it is unknown whether CSFV hijacks other Rab proteins for effective viral infection. Here, we systematically studied the role of Rab14 protein in regulating lipid metabolism for promoting viral assembly. First, Rab14 knockdown and overexpression significantly affected CSFV replication, indicating the essential role of Rab14 in CSFV infection. Interestingly, Rab14 could significantly affect virus replication in the late stage of infection. Mechanistically, CSFV NS5A recruited Rab14 to the ER, followed by ceramide transportation to the Golgi apparatus, where sphingomyelin was synthesized. The experimental data of small molecule inhibitors, RNA interference, and replenishment assay showed that the phosphatidylinositol-3-kinase (PI3K)/AKT/AS160 signaling pathway regulated the function of Rab14 to affect the transport of ceramide. More importantly, sphingomyelin on the Golgi apparatus contributed to the assembly of viral particles. Blockage of the Rab14 regulatory pathway induced the reduction of the content of sphingomyelin on the Golgi apparatus, impairing the assembly of virus particles. Our study clarifies that Rab14 regulates lipid metabolism and promotes CSFV replication, which provides insight into a novel function of Rab14 in regulating vesicles to transport lipids to the viral assembly factory. IMPORTANCE The Rab protein family members participate in the viral replication of multiple viruses and play important roles in the virus infection cycle. Our previous research focused on Rab5/7/11, which regulated the trafficking of vesicles in the early stage of CSFV infection, especially in viral endocytosis. However, the role of other Rab proteins in CSFV replication is unclear and needs further clarification. Strikingly, we screened some Rabs and found the important role of Rab14 in CSFV infection. Virus infection mobilized Rab14 to regulate the vesicle to transport ceramide from the ER to the Golgi apparatus, further promoting the synthesis of sphingomyelin and facilitating virus assembly. The treatment of inhibitors showed that the lipid transport mediated by Rab14 was regulated by the PI3K/AKT/AS160 signaling pathway. Knockdown of Rab14 or the treatment with PI3K/AKT/AS160 inhibitors reduced the ceramide content in infected cells and hindered virus assembly. Our study is the first to explain that vesicular lipid transport regulated by Rab promotes CSFV assembly, which is conducive to the development of antiviral drugs.

Keywords: Rab; ceramide; classical swine fever virus; viral replication

DOI: https://doi.org/10.1128/jvi.00364-23

J Exp Bot. 2023 May 29. pii: erad202. [Epub ahead of print]

Nonspecific lipid transfer protein 1 enhances immunity against tobacco mosaic virus in tobacco.

Feng Zhu, Meng-Yao Cao, Peng-Xiang Zhu, Qi-Ping Zhang, Hon-Ming Lam.

Plant non-specific lipid transfer proteins (nsLTPs) are small, cysteine-rich proteins that play significant roles in biotic and abiotic stress responses. However, the molecular mechanism of their functions against viral infections remains unclear. Here a type-I nsLTP, NbLTP1, was functionally analyzed in the immunity against tobacco mosaic virus (TMV) in Nicotiana benthamiana using virus-induced gene silencing (VIGS) and transgenic technology. NbLTP1 was inducible by TMV infection, and its silencing increased TMV-induced oxidative damage and reactive oxygen species (ROS) production, compromised local and systemic resistance to TMV, and inactivated salicylic acid (SA) biosynthesis and its downstream signaling pathway. The effects of NbLTP1-silencing were partially restored by exogenous SA. Overexpressing NbLTP1 activated ROS scavenging-related genes to increase cell membrane stability and maintain redox homeostasis, confirming that an early ROS burst followed by ROS suppression at the later phases of pathogenesis is essential for resistance to TMV infection. The cell-wall localization of NbLTP1 was beneficial to viral resistance. Overall, our results showed that NbLTP1 positively regulates the plant immunity against viral infection through upregulating SA biosynthesis and its downstream signaling component, Nonexpressor of Pathogenesis-Related 1 (NPR1) which in turn activates pathogenesis-related genes, and by suppressing ROS accumulation at the later phases of viral pathogenesis.

Keywords: Nicotiana benthamiana ; nonspecific lipid transfer proteins (nsLTPs); plant immunity; reactive oxygen species (ROS); salicylic acid; tobacco mosaic virus

DOI: https://doi.org/10.1093/jxb/erad202

J Cell Sci. 2021 Aug 01. pii: jcs252981. [Epub ahead of print]134(15):

TFEB - at the crossroads of host-pathogen interactions.

Keerti, Aarti Pant, Ravi Manjithaya.

The existence of constantly evolving dynamic interactions between the host and the pathogen determines their fate in this continuous arms race. Hence, identifying the molecular basis of processes that reinforce host defensive strategies to eliminate intracellular pathogens is of utmost significance. Pathogenic intrusion activates autophagy and phagocytic pathways that culminate in the lysosome, a vital organelle responsible for pathogen clearance. The transcription factor TFEB plays a pivotal role in autophagy-lysosomal function. Although TFEB is an emerging transcription factor in the field of immune signaling pathways, its role in infectious diseases remains contentious. Recent evidence suggests that infection with certain bacterial and viral pathogens causes TFEB, which is normally located in the cytoplasm, to translocate to the nucleus. There, it activates the transcription of genes that trigger the autophagy-lysosomal and inflammatory pathways to target intracellular pathogens. It is known that some pathogens modulate TFEB to establish themselves inside the host; in some cases, pathogens restrict TFEB to the cytoplasm, whereas in others, functional TFEB fuels pathogen survival and replication. However, the key regulators and molecular mechanisms that decide the outcome of TFEB function during intracellular infection are not clear. In this Review, we attempt to dissect the complex functions of TFEB in host-pathogen interactions and explore the suitability of TFEB as a therapeutic target of clinical relevance.

Keywords: Autophagy; Host-directed therapy; Infection; Inflammatory; Innate immunity; Lysosome; Nuclear translocation; TFEB; Therapeutics

DOI: https://doi.org/10.1242/jcs.252981