bims-mevinf 2023-05-28 papers

Issue of 2023‒05‒28
five papers selected by
Alexander Ivanov

EMBO J. 2023 May 23. e112542

Coronaviral ORF6 protein mediates inter-organelle contacts and modulates host cell lipid flux for virus production.

Mengzhen Yue, Bing Hu, Jiajia Li, Ruifeng Chen, Zhen Yuan, Hurong Xiao, Haishuang Chang, Yaming Jiu, Kun Cai, Binbin Ding.

Lipid droplets (LDs) form inter-organelle contacts with the endoplasmic reticulum (ER) that promote their biogenesis, while LD contacts with mitochondria enhance β-oxidation of contained fatty acids. Viruses have been shown to take advantage of lipid droplets to promote viral production, but it remains unclear whether they also modulate the interactions between LDs and other organelles. Here, we showed that coronavirus ORF6 protein targets LDs and is localized to the mitochondria-LD and ER-LD contact sites, where it regulates LD biogenesis and lipolysis. At the molecular level, we find that ORF6 inserts into the LD lipid monolayer via its two amphipathic helices. ORF6 further interacts with ER membrane proteins BAP31 and USE1 to mediate ER-LDs contact formation. Additionally, ORF6 interacts with the SAM complex in the mitochondrial outer membrane to link mitochondria to LDs. In doing so, ORF6 promotes cellular lipolysis and LD biogenesis to reprogram host cell lipid flux and facilitate viral production.

Keywords: ORF6; endoplasmic reticulum; lipid droplets; mitochondria; organelle interaction

DOI: https://doi.org/10.15252/embj.2022112542

Int J Mol Sci. 2023 May 15. pii: 8781. [Epub ahead of print]24(10):

PEMT Mediates Hepatitis C Virus-Induced Steatosis, Explains Genotype-Specific Phenotypes and Supports Virus Replication.

Mosleh Abomughaid, Enoch S E Tay, Russell Pickford, Chandra Malladi, Scott A Read, Jens R Coorssen, Brian S Gloss, Jacob George, Mark W Douglas.

The hepatitis C virus (HCV) relies on cellular lipid pathways for virus replication and also induces liver steatosis, but the mechanisms involved are not clear. We performed a quantitative lipidomics analysis of virus-infected cells by combining high-performance thin-layer chromatography (HPTLC) and mass spectrometry, using an established HCV cell culture model and subcellular fractionation. Neutral lipid and phospholipids were increased in the HCV-infected cells; in the endoplasmic reticulum there was an ~four-fold increase in free cholesterol and an ~three-fold increase in phosphatidyl choline (p < 0.05). The increase in phosphatidyl choline was due to the induction of a non-canonical synthesis pathway involving phosphatidyl ethanolamine transferase (PEMT). An HCV infection induced expression of PEMT while knocking down PEMT with siRNA inhibited virus replication. As well as supporting virus replication, PEMT mediates steatosis. Consistently, HCV induced the expression of the pro-lipogenic genes SREBP 1c and DGAT1 while inhibiting the expression of MTP, promoting lipid accumulation. Knocking down PEMT reversed these changes and reduced the lipid content in virus-infected cells. Interestingly, PEMT expression was over 50% higher in liver biopsies from people infected with the HCV genotype 3 than 1, and three times higher than in people with chronic hepatitis B, suggesting that this may account for genotype-dependent differences in the prevalence of hepatic steatosis. PEMT is a key enzyme for promoting the accumulation of lipids in HCV-infected cells and supports virus replication. The induction of PEMT may account for virus genotype specific differences in hepatic steatosis.

Keywords: PEMT; hepatitis C virus; lipid metabolism; lipidomics; phosphatidyl choline; steatosis

DOI: https://doi.org/10.3390/ijms24108781

Rev Assoc Med Bras (1992). 2023 ;pii: S0104-42302023000500606. [Epub ahead of print]69(5): e20221163

Effects of hepatitis C virus genotypes and viral load on glucose and lipid metabolism after sustained virological response with direct-acting antivirals.

Jucéli Márcia Hendges Sparvoli, Antonio Cardoso Sparvoli, Afonso Alexandre Pereira, Ana Luisa Machado de Paula, Laís Garcia, Carla Vitola Gonçalves.

OBJECTIVE: The objective of this study, carried out at the university hospital of the Federal University of Rio Grande, was to assess whether the treatment of chronic hepatitis C with direct-acting antivirals and the sustained virological response will affect the metabolic influences of the hepatitis C virus and whether these effects will vary according to genotypes and virus load.METHODS: This is an intervention pre-post study, carried out from March 2018 to December 2019, evaluating 273 hepatitis C virus patients treated with direct-acting antivirals. Inclusion criteria included being monoinfected with hepatitis C virus and achieving sustained virological response . Exclusion criteria included the presence of decompensated cirrhosis or co-infected with hepatitis B virus or human immunodeficiency virus. Genotypes, genotype 1 subtypes, and hepatitis C virus viral load were analyzed. Glucose metabolism was evaluated by the Homeostasis Model Assessment-insulin resistance indices: Homeostasis Model Assessment-β, TyG, and HbA1c, measured at the beginning of treatment and in sustained virological response. Statistical analysis with a T test by paired comparison of the means of the variables in the pretreatment and in the sustained virological response.
RESULTS: Homeostasis Model Assessment-insulin resistance analysis: there were no significant differences between pretreatment and sustained virological response. Homeostasis Model Assessment-β analysis: significant increase in genotype 1 patients (p<0.028). TyG index analysis: significant increase in genotype 1b (p<0.017), genotype 3 (p<0.024), and genotype non-1 with low viral load (p<0.039). HbA1c analysis: significant decrease in genotype 3 (p<0.001) and genotype non-1 patients with low viral load (p<0.005).
CONCLUSION: We detected significant metabolic influences after sustained virological response: impairment in lipid profile and improvements in the glucose metabolism. We found significant differences in genotype dependence, genotype 1 subtypes, and viral load.

DOI: https://doi.org/10.1590/1806-9282.20221163

Viruses. 2023 May 18. pii: 1191. [Epub ahead of print]15(5):

Micro-CT Features of Lung Consolidation, Collagen Deposition and Inflammation in Experimental RSV Infection Are Aggravated in the Absence of Nrf2.

Teodora Ivanciuc, Igor Patrikeev, Yue Qu, Massoud Motamedi, Yava Jones-Hall, Antonella Casola, Roberto P Garofalo.

Severe respiratory syncytial virus (RSV) infections in early life have been linked to the development of chronic airway disease. RSV triggers the production of reactive oxygen species (ROS), which contributes to inflammation and enhanced clinical disease. NF-E2-related factor 2 (Nrf2) is an important redox-responsive protein that helps to protect cells and whole organisms from oxidative stress and injury. The role of Nrf2 in the context of viral-mediated chronic lung injury is not known. Herein, we show that RSV experimental infection of adult Nrf2-deficient BALB/c mice (Nrf2-/-; Nrf2 KO) is characterized by enhanced disease, increased inflammatory cell recruitment to the bronchoalveolar compartment and a more robust upregulation of innate and inflammatory genes and proteins, compared to wild-type Nrf2+/+ competent mice (WT). These events that occur at very early time points lead to increased peak RSV replication in Nrf2 KO compared to WT mice (day 5). To evaluate longitudinal changes in the lung architecture, mice were scanned weekly via high-resolution micro-computed tomography (micro-CT) imaging up to 28 days after initial viral inoculation. Based on micro-CT qualitative 2D imaging and quantitative reconstructed histogram-based analysis of lung volume and density, we found that RSV-infected Nrf2 KO mice developed significantly greater and prolonged fibrosis compared to WT mice. The results of this study underscore the critical role of Nrf2-mediated protection from oxidative injury, not only in the acute pathogenesis of RSV infection but also in the long-term consequences of chronic airway injury.

Keywords: Nrf2; airway remodeling; collagen; micro-CT; respiratory syncytial virus

DOI: https://doi.org/10.3390/v15051191

Biomolecules. 2023 May 09. pii: 803. [Epub ahead of print]13(5):

The Role of Spermidine and Its Key Metabolites in Important, Pathogenic Human Viruses and in Parasitic Infections Caused by Plasmodium falciparum and Trypanosoma brucei.

Annette Kaiser.

The triamine spermidine is a key metabolite of the polyamine pathway. It plays a crucial role in many infectious diseases caused by viral or parasitic infections. Spermidine and its metabolizing enzymes, i.e., spermidine/spermine-N1-acetyltransferase, spermine oxidase, acetyl polyamine oxidase, and deoxyhypusine synthase, fulfill common functions during infection in parasitic protozoa and viruses which are obligate, intracellular parasites. The competition for this important polyamine between the infected host cell and the pathogen determines the severity of infection in disabling human parasites and pathogenic viruses. Here, we review the impact of spermidine and its metabolites in disease development of the most important, pathogenic human viruses such as SARS-CoV-2, HIV, Ebola, and in the human parasites Plasmodium and Trypanosomes. Moreover, state-of-the-art translational approaches to manipulate spermidine metabolism in the host and the pathogen are discussed to accelerate drug development against these threatful, infectious human diseases.

Keywords: drug development; spermidine; viral and parasitic infections

DOI: https://doi.org/10.3390/biom13050803