SENP3-mediated host defense response contains HBV replication and restores protein synthesis

TRIM28 functions as SUMO ligase to SUMOylate TRAF6 and regulate NF-κB activation in HBV-replicating cells

BACKGROUND

Hepatitis B virus (HBV) is a pathogen that poses a serious threat to human health. The interaction between HBV and host has made great progress in recent years. SUMOylation is involved in virus-related cancer progression, but there are fewer studies on the mechanism of SUMOylation on HBV replication and antiviral defense. Tumor necrosis factor receptor-associated factor 6 (TRAF6) is a critical adaptor of the NF-κB pathways. Here, we focus on the roles of TRIM28 in regulating TRAF6 SUMOylation in HBV-replicating cells.

METHODS

The SUMO1-modified TRAF6 proteins were enriched from total cellular proteins by immunoprecipitation with anti-SUMO1 antibody, then the SUMOylated TRAF6 was detected by western blot using an anti-TRAF6 antibody. The interaction between TRAF6 and TRIM28 was identified by immunoprecipitation and LC-MS/MS. The modification sites of TRAF6 SUMOylation were identified by amino acid site mutation. Expression and localization of TRAF6 and TRIM28 were assessed by immunohistochemistry and immunofluorescence. The hydrodynamic injection HBV mouse model was used to determine the function of TRIM28-mediated TRAF6 SUMOylation in vivo.

RESULTS

The results show that the levels of SUMO1-modified TRAF6 are elevated in HBV-replicating cells. Lys453 is a major SUMO1 modification site of TRAF6. There is an antagonistic interaction between SUMOylation and ubiquitination of TRAF6 protein. The SUMO ligase TRIM28 is responsible for catalyzing TRAF6 SUMOylation. Compared to the wild-type TRAF6, its SUMO site mutant TRAF6K453R promotes NF-κB activation. Moreover, TRIM28 overexpression attenuates TRAF6-mediated NF-κB activation, thereby inhibiting HBV replication in vivo.

CONCLUSIONS

Our findings demonstrate that SUMO ligase TRIM28 affects the ability of TRAF6 on NF-κB activation, nucleocytoplasmic shuttling and HBV replication-related indicators. Our data reveal that TRIM28-mediated SUMOylation of TRAF6 is a novel mechanism to regulate the inflammatory response, which may pave the way for new strategies to control anti-HBV.

SENP3: Cancers and diseases

SUMOylation is a protein modification process that involves the covalent attachment of a small ubiquitin-like modifier (SUMO) to a specific lysine residue on the target protein. This modification can influence the function, localization, stability, and interactions of proteins, thereby regulating various cellular processes. Altering the SUMOylation of certain proteins is expected to be a potential approach for treating specific cancers and diseases. Among these, SENP3 can affect target proteins by regulating the deSUMOylation process, which in turn influences the transcriptional activity of downstream genes, playing a role in either promoting or inhibiting cancer. SENP3 regulates the SUMO status of proteins in numerous signaling pathways, modulating the activity of specific signaling molecules to impact cellular responses and tumor progression. Additionally, SENP3 promotes cell growth and division by deSUMOylating key cyclins. In the context of DNA repair, SENP3 regulates the activity of proteins associated with DNA repair by deSUMOylating repair factors, thereby enhancing DNA repair and maintaining genome stability. Furthermore, SENP3 has specific functions in various other diseases. The complex roles of SENP3 indicate its potential as both a therapeutic target and a biomarker.

Identification of Host Proteins Involved in Hepatitis B Virus Genome Packaging

A critical part of the hepatitis B virus (HBV) life cycle is the packaging of the pregenomic RNA (pgRNA) into nucleocapsids. While this process is known to involve several viral elements, much less is known about the identities and roles of host proteins in this process. To better understand the role of host proteins, we isolated pgRNA and characterized its protein interactome in cells expressing either packaging-competent or packaging-incompetent HBV genomes. We identified over 250 host proteins preferentially associated with pgRNA from the packaging-competent version of the virus. These included proteins already known to support capsid formation, enhance viral gene expression, catalyze nucleocapsid dephosphorylation, and bind to the viral genome, demonstrating the ability of the approach to effectively reveal functionally significant host-virus interactors. Three of these host proteins, AURKA, YTHDF2, and ATR, were selected for follow-up analysis. RNA immunoprecipitation qPCR (RIP-qPCR) confirmed pgRNA-protein association in cells, and siRNA knockdown of the proteins showed decreased encapsidation efficiency. This study provides a template for the use of comparative RNA-protein interactome analysis in conjunction with virus engineering to reveal functionally significant host-virus interactions.

The role and mechanism of SUMO modification in liver disease

Liver disease affects millions of people in the world, and China has the highest prevalence of liver disease in the world. Small ubiquitin-related modifier (SUMO) modification is a highly conserved post-translational modification of proteins. They are widely expressed in a variety of tissues, including the heart, liver, kidney and lung. SUMOylation of protein plays a key role in the occurrence and development of liver disease. Therefore, this study reviewed the effects of SUMO protein on non-alcoholic fatty liver disease (NAFLD), alcoholic liver disease (ALD), viral hepatitis, hepatic fibrosis (HF), hepatocellular carcinoma (HCC), and other liver diseases to provide novel strategies for targeted treatment of liver disease.

Abnormal protein SUMOylation in liver disease: novel target for therapy

SUMOylation is an important protein post-translational modification (PTM) process, in which the small ubiquitin-like modifier (SUMO) protein covalently binds to the target protein and regulates stability, subcellular localization, and protein-protein interaction of the target protein. Protein SUMOylation exerts crucial regulatory function in the liver, and its abnormalities are associated with various liver-related disease processes. This review focuses on the biological functions of protein SUMOylation in liver-related diseases in recent years, summarizes the molecular mechanisms of SUMOylation in the replication of hepatitis viruses and the occurrence of hepatocellular carcinoma, and discusses the significance of SUMOylation in liver-related disorders, which is essential for understanding liver biological processes and formulating therapeutic strategies.

SUMOylation in Viral Replication and Antiviral Defense

SUMOylation is a ubiquitination-like post-translational modification that plays an essential role in the regulation of protein function. Recent studies have shown that proteins from both RNA and DNA virus families can be modified by SUMO conjugation, which facilitates viral replication. Viruses can manipulate the entire process of SUMOylation through interplay with the SUMO pathway. By contrast, SUMOylation can eliminate viral infection by regulating host antiviral immune components. A deeper understanding of how SUMOylation regulates viral proteins and cellular antiviral components is necessary for the development of effective antiviral therapies. In the present review, the regulatory mechanism of SUMOylation in viral replication and infection and the antiviral immune response, and the consequences of this regulation for viral replication and engagement with antiviral innate immunity are summarized. The potential therapeutic applications of SUMOylation in diseases caused by viruses are also discussed.

Epigenetic basis of oncogenic-Kras-mediated epithelial-cellular proliferation and plasticity

Oncogenic Kras induces a hyper-proliferative state that permits cells to progress to neoplasms in diverse epithelial tissues. Depending on the cell of origin, this also involves lineage transformation. Although a multitude of downstream factors have been implicated in these processes, the precise chronology of molecular events controlling them remains elusive. Using mouse models, primary human tissues, and cell lines, we show that, in Kras-mutant alveolar type II cells (AEC2), FOSL1-based AP-1 factor guides the mSWI/SNF complex to increase chromatin accessibility at genomic loci controlling the expression of genes necessary for neoplastic transformation. We identified two orthogonal processes in Kras-mutant distal airway club cells. The first promoted their transdifferentiation into an AEC2-like state through NKX2.1, and the second controlled oncogenic transformation through the AP-1 complex. Our results suggest that neoplasms retain an epigenetic memory of their cell of origin through cell-type-specific transcription factors. Our analysis showed that a cross-tissue-conserved AP-1-dependent chromatin remodeling program regulates carcinogenesis.

The Role of Protein SUMOylation in Human Hepatocellular Carcinoma: A Potential Target of New Drug Discovery and Development

Small ubiquitin-like modifier (SUMO) is a highly conserved post-translational modification protein, mainly found in eukaryotes. They are widely expressed in different tissues, including the liver. As an essential post-translational modification, SUMOylation is involved in many necessary regulations in cells. It plays a vital role in DNA repair, transcription regulation, protein stability and cell cycle progression. Increasing shreds of evidence show that SUMOylation is closely related to Hepatocellular carcinoma (HCC). The high expression of SUMOs in the inflammatory hepatic tissue may lead to the carcinogenesis of HCC. At the same time, SUMOs will upregulate the proliferation and survival of HCC, migration, invasion and metastasis of HCC, tumour microenvironment as well as drug resistance. This study reviewed the role of SUMOylation in liver cancer. In addition, it also discussed natural compounds that modulate SUMO and target SUMO drugs in clinical trials. Considering the critical role of SUMO protein in the occurrence of HCC, the drug regulation of SUMOylation may become a potential target for treatment, prognostic monitoring and adjuvant chemotherapy of HCC.

Deneddylation by SENP8 restricts hepatitis B virus propagation

Proteins newly synthesized from messenger RNA undergo Posttranslational modifications (PTMs) such as phosphorylation, glycosylation, methylation, and ubiquitination. These PTMs have important roles in protein stability, localization, and conformation and have been reported to be involved in hepatitis B virus (HBV) propagation. Although ubiquitination plays an essential role in HBV life cycles, the involvement of ubiquitin-like proteins (UBLs) in HBV life cycles has been understudied. Through comprehensive gain- and loss-of-function screening of UBLs, we observed that neddylation, a PTM in which neural precursor cell, expressed developmentally downregulated 8 (NEDD8) is conjugated to substrate proteins, was required for efficient HBV propagation. We also found that overexpression of sentrin-specific protease 8 (SENP8), which cleaves conjugated NEDD8, suppressed HBV propagation. Further, the catalytic activity of SENP8 was required for the suppression of HBV propagation. These results indicated that the reduction of neddylation negatively regulated HBV propagation. In addition, we demonstrated that suppression of HBV propagation via SENP8 overexpression was independent of hepatitis B protein X (HBx) and HBV promoter activity. Therefore, our data suggested that neddylation plays an important role in the late stages of HBV life cycles.

Combined identification of ARID1A, CSMD1, and SENP3 as effective prognostic biomarkers for hepatocellular carcinoma

Background: The current study aimed to understand the genetic landscape and investigate the diagnostic and prognostic biomarkers of primary hepatocellular carcinoma (HCC).

Methods: A cohort of 36 Chinese HCC samples with hepatitis B virus (HBV) infection was examined by whole-exome sequencing (WES). Prognosis-related alterations were identified and further verified in the TCGA database and GSE65372 profiles in the GEO database. A Chinese replication cohort of 180 HCC samples with HBV infection was collected to evaluate the candidate genes by immunohistochemical analysis. A receiver operating characteristic (ROC) curve analysis evaluated the prognostic power of candidate genes. Finally, EdU and transwell invasion assay were performed to detect the function of candidate genes.

Results: A total of 11 novel genes showed a significant association with HCC in the discovery cohort. The data were verified using the GEO and TCGA databases, and the expression of ARID1A, CSMD1, and SENP was evaluated in the replication cohort. Furthermore, ARID1A, CSMD1, and SENP3 are effective prognostic biomarkers for HCC patients in the replication population.

Conclusions: Molecular heterogeneity was detected in HCC patients, and ARID1A, CSMD1, and SENP3 were identified as effective HCC prognosis biomarkers. CSMD1 prevents HCC by suppressing cell invasion.

The Critical Roles of the SUMO-Specific Protease SENP3 in Human Diseases and Clinical Implications

Post-translational modification by SUMO (small ubiquitin-like modifier) proteins has been shown to regulate a variety of functions of proteins, including protein stability, chromatin organization, transcription, DNA repair, subcellular localization, protein–protein interactions, and protein homeostasis. SENP (sentrin/SUMO-specific protease) regulates precursor processing and deconjugation of SUMO to control cellular mechanisms. SENP3, which is one of the SENP family members, deconjugates target proteins to alter protein modification. The effect of modification via SUMO and SENP3 is crucial to maintain the balance of SUMOylation and guarantee normal protein function and cellular activities. SENP3 acts as an oxidative stress-responsive molecule under physiological conditions. Under pathological conditions, if the SUMOylation process of proteins is affected by variations in SENP3 levels, it will cause a cellular reaction and ultimately lead to abnormal cellular activities and the occurrence and development of human diseases, including cardiovascular diseases, neurological diseases, and various cancers. In this review, we summarized the most recent advances concerning the critical roles of SENP3 in normal physiological and pathological conditions as well as the potential clinical implications in various diseases. Targeting SENP3 alone or in combination with current therapies might provide powerful targeted therapeutic strategies for the treatment of these diseases.

Sumoylation in liver disease

Small ubiquitin-like modifiers (SUMO) are highly conserved post-translational modification proteins that are present in eukaryotic cells. They are extensively expressed in diverse tissues, including the heart, liver, kidney, and lungs. SUMOylation, a crucial post-translational modification, exhibits a strong effect on DNA repair, transcriptional regulation, protein stability and cell cycle progression. Increasing evidence has demonstrated that SUMOylation is closely related to the development of liver disease. Therefore, the effects of SUMOylation in liver diseases, such as Hepatocellular carcinoma (HCC), viral hepatitis, non-alcoholic fatty liver disease (NAFLD), cirrhosis and primary biliary cirrhosis (PBC) were reviewed in this study. Specifically, SUMO1 was found to promote the invasion and metastasis of HCC and may promote hypoxia-mediated P65 nuclear transport while accelerating the progression of HCC. In addition, SUMO1-modified centrosomal P4.1-associated protein (CAPA) was observed to be overexpressed in Hepatitis B virus (HBV)-related HCC in response to TNF-α stimulation. Furthermore, SUMOylated CAPA was found to induce HBX-triggered NF-κB activation. Considering the diversity and significance of SUMOylation, targeting of the SUMOylation pathway may serve as an effective approach in the treatment of liver diseases.