Hepatic expression of proteasome subunit alpha type-6 is upregulated during viral hepatitis and putatively regulates the expression of ISG15 ubiquitin-like modifier, a proviral host gene in hepatitis C virus infection

Thioredoxin Domain Containing 5 (TXNDC5): Friend or Foe?

This review focuses on the thioredoxin domain containing 5 (TXNDC5), also known as endoplasmic reticulum protein 46 (ERp46), a member of the protein disulfide isomerase (PDI) family with a dual role in multiple diseases. TXNDC5 is highly expressed in endothelial cells, fibroblasts, pancreatic β-cells, liver cells, and hypoxic tissues, such as cancer endothelial cells and atherosclerotic plaques. TXNDC5 plays a crucial role in regulating cell proliferation, apoptosis, migration, and antioxidative stress. Its potential significance in cancer warrants further investigation, given the altered and highly adaptable metabolism of tumor cells. It has been reported that both high and low levels of TXNDC5 expression are associated with multiple diseases, such as arthritis, cancer, diabetes, brain diseases, and infections, as well as worse prognoses. TXNDC5 has been attributed to both oncogenic and tumor-suppressive features. It has been concluded that in cancer, TXNDC5 acts as a foe and responds to metabolic and cellular stress signals to promote the survival of tumor cells against apoptosis. Conversely, in normal cells, TXNDC5 acts as a friend to safeguard cells against oxidative and endoplasmic reticulum stress. Therefore, TXNDC5 could serve as a viable biomarker or even a potential pharmacological target.

Organizing training workshops on gene literature retrieval, profiling, and visualization for early career researchers

Early-career researchers must acquire the skills necessary to effectively search and extract information from biomedical literature. This ability is for instance crucial for evaluating the novelty of experimental results, and assessing potential publishing opportunities. Given the rapidly growing volume of publications in the field of biomedical research, new systematic approaches need to be devised and adopted for the retrieval and curation of literature relevant to a specific theme. In this context, we present a hands-on training curriculum aimed at retrieval, profiling, and visualization of literature associated with a given topic. The curriculum was implemented in a workshop in January 2021. Here we provide supporting material and step-by-step implementation guidelines with the ISG15 gene literature serving as an illustrative use case. Workshop participants can learn several skills, including: 1) building and troubleshoot PubMed queries in order to retrieve the literature associated with a gene of interest; 2) identifying key concepts relevant to given themes (such as cell types, diseases, and biological processes); 3) measuring the prevalence of these concepts in the gene literature; 4) extracting key information from relevant articles, and 5) developing a background section or summary on the basis of this information. Finally, trainees can learn to consolidate the structured information captured through this process for presentation via an interactive web application.

PSMB4 Degrades the Porcine Reproductive and Respiratory Syndrome Virus Nsp1α Protein via the Autolysosome Pathway and Induces the Production of Type I Interferon

Porcine reproductive and respiratory syndrome virus (PRRSV) causes respiratory disease in pigs of all ages and reproductive failure in sows, resulting in great economic losses to the swine industry. In this work, we identified the interaction between PSMB4 and PRRSV Nsp1α by yeast two-hybrid screening. The PSMB4-Nsp1α interaction was further confirmed by coimmunoprecipitation, glutathione S-transferase (GST) pulldown, and laser confocal experiments. The PCPα domain (amino acids 66 to 166) of Nsp1α and the C-terminal domain (amino acids 250 to 264) of PSMB4 were shown to be critical for the PSMB4-Nsp1α interaction. PSMB4 overexpression reduced PRRSV replication, whereas PSMB4 knockdown elicited opposing effects. Mechanistically, PSMB4 targeted K169 in Nsp1α for K63-linked ubiquitination and targeted Nsp1α for autolysosomal degradation by interacting with LC3 to enhance the activation of the lysosomal pathway. Meanwhile, we found that PSMB4 activated the NF-κB signaling pathway to produce type I interferons by downregulating the expression of IκBα and p-IκBα. In conclusion, our data revealed a new mechanism of PSMB4-mediated restriction of PRRSV replication, whereby PSMB4 was found to induce Nsp1α degradation and type I interferon expression, in order to impede the replication of PRRSV. IMPORTANCE In the swine industry, PRRSV is a continuous threat, and the current vaccines are not effective enough to block it. This study determined that PSMB4 plays an antiviral role against PRRSV. PSMB4 was found to interact with PRRSV Nsp1α, mediate K63-linked ubiquitination of Nsp1α at K169, and thus trigger its degradation via the lysosomal pathway. Additionally, PSMB4 activated the NF-κB signaling pathway to produce type I interferons by downregulating the expression of IκBα and p-IκBα. This study extends our understanding of the proteasome subunit PSMB4 against PRRSV replication and will contribute to the development of new antiviral strategies.

Organizing gene literature retrieval, profiling, and visualization training workshops for early career researchers

Developing the skills needed to effectively search and extract information from biomedical literature is essential for early-career researchers. It is, for instance, on this basis that the novelty of experimental results, and therefore publishing opportunities, can be evaluated. Given the unprecedented volume of publications in the field of biomedical research, new systematic approaches need to be devised and adopted for the retrieval and curation of literature relevant to a specific theme. Here we describe a hands-on training curriculum aimed at retrieval, profiling, and visualization of literature associated with a given topic. This curriculum was implemented in a workshop in January 2021. We provide supporting material and step-by-step implementation guidelines with the ISG15 gene literature serving as an illustrative use case. Through participation in such a workshop, trainees can learn: 1) to build and troubleshoot PubMed queries in order to retrieve the literature associated with a gene of interest; 2) to identify key concepts relevant to given themes (such as cell types, diseases, and biological processes); 3) to measure the prevalence of these concepts in the gene literature; 4) to extract key information from relevant articles, and 5) to develop a background section or summary on the basis of this information. Finally, trainees can learn to consolidate the structured information captured through this process for presentation via an interactive web application.

Interferon-stimulated gene 15 in hepatitis B-related liver diseases

This study investigates the association of Interferon-stimulated gene 15 (ISG15) polymorphisms, ISG15 serum levels and expression with HBV-related liver diseases. The ISG15 promoter and the two exons of the gene were screened for polymorphisms in 766 HBV-infected patients and in 223 controls. Soluble ISG15 levels were measured by ELISA. ISG15 mRNA expression was quantified by qRT-PCR in 36 tumor and adjacent non-tumor tissues. The exon 2 allele rs1921A was found associated with decreased progression of HBV-related liver diseases (LC vs. CHB: OR = 0.6, 95%CI = 0.4-0.8, adjusted P = 0.003; HCC vs. CHB: OR = 0.6, 95%CI = 0.4-0.9, adjusted P = 0.005). The rs1921AA genotype was associated with low levels of AST, ALT and total bilirubin, but with high prothrombin levels (P < 0.05). ISG15 serum levels were higher among HBV patients compared to controls (P < 0.0001) and positively associated with HBV-related liver diseases, with highest levels among LC patients. ISG15 levels were correlated with HBV-DNA loads (P = 0.001). In non-tumor tissues from HCC patients, ISG15 mRNA expression was increased in HBV compared to non-HBV infection (P = 0.016). The ISG15 rs1921 variant and ISG15 expression are associated with HBV-related liver diseases. Taken together, ISG15 appears to be a proviral factor involved in HBV replication and triggering progression of HBV-related liver diseases.

Regulatory responses of hepatocytes, macrophages and vascular endothelial cells to magnesium deficiency

The liver is the organ that responds to nutritional disturbances including magnesium deficiency. The present study evaluated cellular responses to magnesium deficiency using model cells of the liver, namely, HepG2 cells as hepatocytes, RAW264.7 cells as Kupffer cells and human umbilical vein endothelial cells (HUVECs) as vascular endothelial cells; we examined effects of culture with magnesium deficient medium on cell responses in individual types of cells as well as interactive responses among cells. Metabolomic analyses indicated that magnesium deficiency differentially affected the cellular content of metabolites among HepG2 cells, RAW264.7 cells and HUVECs. The cellular content of the metabolites in HepG2 cells and HUVECs was also affected by the conditioned medium from RAW264.7 cells cultured with the magnesium-deficient media. The changes in HUVECs partly resembled those of the livers of magnesium-deficient rats previously described. RNA-seq analyses indicated that magnesium deficiency modulated the expression levels of molecules related to the ubiquitin-proteasome pathway and oxidative stress/antioxidant response in HepG2 cells and RAW264.7 cells, respectively. Furthermore, when HUVECs were co-cultured with RAW264.7 cells, lipopolysaccharide-induced expression of interleukin (IL)-1β and IL-6 was enhanced by magnesium deficiency, depending on the presence of RAW264.7 cells. The present study reveals that magnesium deficiency affects cellular metabolism in HepG2 liver cells, RAW264.7 macrophages and HUVECs, and that the modulation of cellular responses to extracellular magnesium deficiency in HUVECs depends on the presence of RAW264.7 cells. The complex responses in individual cells and through cell interactions partly explain the regulatory reaction to magnesium deficiency in the liver.

Transcriptome profiling and expression analysis of immune responsive genes in the liver of Golden mahseer (Tor putitora) challenged with Aeromonas hydrophila

Transcriptome profiling has been used to decipher the novel mechanisms behind immune responses of the fishes. However, the molecular mechanism underlining immune response in mahseer is not studied so far. Fishes are greatly affected by bacterial pathogens such as Aeromonas hydrophila. In this study, transcriptome response of golden mahseer (Tor putitora) infected with A. hydrophila was examined using paired end Illumina sequencing of liver tissue to understand the immune response of the fish. The de novo assembly generated 61,042 unigenes ranging from 200 to 9322 bp in length and an average length of 463 bp. The gene ontology annotations resulted a total of 131,826 term assignments to the annotated transcriptome including 60,846 (46.16%) allocations from the biological process; 21,603 (16.39%) from molecular function and 49,377 (37.46%) from cellular components. Differential gene expression analysis of the transcriptome data from challenged and control group revealed 1104 upregulated and 1304 down-regulated unigenes. The differentially expressed genes were mainly involved in the pathways including cell surface receptor signaling, TH1 and TH2 cell differentiation, pathogen recognition, and immune system process/defense response especially complement cascade. Twelve unigenes including ankyrin, serum amyloid, hsp4b, STAT3, complement factor c3 and c7 were validated using qPCR and found differentially expressed in accordance with in silico expression analysis. The results obtained in this study will provide the first and crucial information on the molecular mechanism of mahseer fishes against bacterial infection.

Elevated Expression of Chemokine CXCL13 in Chronic Hepatitis B Patients Links to Immune Control during Antiviral Therapy

C–X–C-chemokine ligand 13 (CXCL13), the ligand for C–X–C chemokine receptor type 5 (CXCR5), is a major regulator of B-cell trafficking and plays an integral role in age-dependent clearance of hepatitis B virus (HBV) in the mouse model. However, the expression and function of CXCL13 in patients with chronic hepatitis B (CHB) remain unknown. By use of liver cell subpopulations isolated from CHB patients, we found that CXCL13 mRNA was abundantly expressed in Kupffer cells (KCs), but not in primary hepatocytes, liver sinusoidal endothelial cells, and hepatic stellate cells. Interestingly, KC isolated from HBV-positive liver had much higher level of CXCL13 expression than non-HBV-infected controls. And its expression was induced by toll-like receptor 3 ligand poly I:C stimulation. Moreover, intense expression of CXCL13 protein and accumulation of CD4⁺ T and B cells were evident in follicular-like structures in the liver tissue of CHB patients, which indicated its chemotactic effect on CXCR5⁺ CD4⁺ cells and B cells. Consistently, the levels of serum CXCL13 were significantly higher in the CHB patients than in healthy controls. Furthermore, CXCL13 concentration was increased in the complete response (CR) group during weeks 0–12 and did not change significantly during the course of telbivudine treatment, compared with the patients who didn’t achieve CR. In conclusion, the HBV-related increase of CXCL13 production in KC and serum CXCL13 level during telbivudine treatment might be associated with immune control of chronic HBV infection.