TRAF7 negatively regulates the RLR signaling pathway by facilitating the K48-linked ubiquitination of TBK1

Identification of host factors affecting Chicken Infectious Anemia Virus infection and pathogenicity through RNA-seq and LC-MS

Chicken Infectious Anemia Virus (CIAV) infection causes severe anemia, hematopoietic disorders, and immunosuppression in poultry. However, the mechanisms underlying its pathogenicity remain poorly understood. In this study, RNA sequencing (RNA-seq) was employed to investigate the transcriptional response of MSB1 cells to CIAV infection at 12, 24, and 48 hours post-infection. The results revealed differential gene expression associated with immune response, inflammatory response, apoptosis, and metabolic pathways. Several immune-related factors, including IL18, TRAF1, MYD88, IRF2, and CD28, were found to be downregulated. VP1, the capsid protein of CIAV, plays a significant role in viral pathogenicity. To explore how VP1 affects CIAV replication and pathogenicity, co-immunoprecipitation (Co-IP) was used to identify host proteins interacting with VP1. Liquid chromatography-mass spectrometry (LC-MS) analysis revealed that VP1 interacts with a range of host proteins involved in metabolic pathways, the PI3K-AKT signaling pathway, and ribosomal functions. Based on RNA-seq and LC-MS findings, ANXA6 and HSP90aa1 were identified as key interacting partners, which co-localize in the cytoplasm of infected cells. Both proteins are involved in immune responses and metabolic regulation and were found to be downregulated in CIAV-infected cells. Notably, overexpression of ANXA6 or HSP90aa1 inhibited CIAV infection during the early stages of the viral lifecycle. These findings enhance our understanding of the host factors influencing CIAV infection and provide new insights into potential therapeutic targets for managing CIAV-induced diseases.

TRAF7 knockdown induces cellular senescence and synergizes with lomustine to inhibit glioma progression and recurrence

BACKGROUND

The progression and recurrence are the fatal prognostic factors in glioma patients. However, the therapeutic role and potential mechanism of TRAF7 in glioma patients remain largely unknown.

METHODS

TRAF7 RNA-seq was analysed with the TCGA and CGGA databases between glioma tissues and normal brain tissues. The expression of TRAF7, cellular senescence and cell cycle arrest pathways in glioma tissues and cell lines was detected by real-time quantitative PCR (RT-qPCR), western blotting and immunohistochemistry. The interaction between TRAF7 and KLF4 was determined by Co-immunoprecipitation (Co-IP) assays. The functions of TRAF7 combined with lomustine in glioma were assessed by both in vitro, in vivo and patient-derived primary and recurrent glioma stem cell (GSC) assays.

RESULTS

High TRAF7 expression is closely associated with a higher recurrence rate and poorer overall survival (OS). In vitro, TRAF7 knockdown significantly inhibits glioma cell proliferation, invasion, and migration. RNA-seq analysis revealed that TRAF7 inhibition activates pathways related to cellular senescence and cell cycle arrest. In both in vitro and patient-derived GSC assays, the combination of sh-TRAF7 and lomustine enhanced therapeutic efficacy by inducing senescence and G0/G1 cell cycle arrest, surpassing the effects of lomustine or TRAF7 inhibition alone. Mechanistically, TRAF7 interacts with KLF4, and a rescue assay demonstrated that KLF4 overexpression could reverse the effects of TRAF7 depletion on proliferation and cellular senescence. In vivo, TRAF7 knockdown combined with lomustine treatment effectively suppressed glioma growth.

CONCLUSION

TRAF7 could be used as a predictive biomarker and the potential therapeutic target among National Comprehensive Cancer Network (NCCN) treatment guidelines in the progression and recurrence of glioma. Lomustine, regulating cellular senescence and cell cycle could be the priority choice in glioma patients with high-level TRAF7 expression.

Molecular characterization of TRAF gene family in snakehead (Channa argus)

Tumor necrosis factor receptor-associated factors (TRAFs) act as signal transducers and are critical in many biological processes. However, in contrast to mammals, the function of TRAFs in teleost is still largely unknown. In this study, we identified and cloned eight TRAF genes in snakehead (Channa argus), namely CaTRAF2aa, CaTRAF2ab, CaTRAF2b, CaTRAF3, CaTRAF4a, CaTRAF5, CaTRAF6, and CaTRAF7. Bioinformatics analyses exhibited CaTRAF genes were evolutionarily conserved among teleost. Subcellular localization results demonstrated that eight CaTRAFs were all localized in cytoplasm. These CaTRAFs showed widespread but different expression profiles in various organs/tissues of snakehead and their expression could be induced by IHSV infection. Furthermore, almost all CaTRAFs can be impacted by poly (I:C) stimulation in HKLs. To sum up, this study provides a valuable foundation for further functional research on teleost TRAF genes.

A Pilot Study on the Role of TRAFs in the Development of SARS-CoV-2 Infection Before and After Immunization with AstraZeneca Chadox1 in Mice

The TRAF family of molecules are intracellular signaling adaptors that regulate various signaling pathways. These pathways are not only mediated by the TNFR superfamily and the Toll-like receptor/IL-1 receptor superfamily but also by unconventional cytokine receptors like IL-6 and IL-17 receptors. Overactive immune responses caused by TRAF signaling following the activation of these receptors frequently result in inflammatory and autoimmune diseases such as rheumatoid arthritis, inflammatory bowel disease, psoriasis, and autoinflammatory syndromes. Therefore, it is crucial to comprehend the signaling processes controlled by TRAFs, which have a significant influence on the determination of cell fate (life or death) and the functioning, specialization, and endurance of cells in the innate and adaptive immune systems. Our data indicate that the dysregulation of cellular expression and/or signaling of TRAFs leads to the excessive production of pro-inflammatory cytokines, hence promoting abnormal activation of immune cells. The objective of our investigation was to comprehend the function of these molecules in SARS-CoV-2 infection both prior to and during SARS-CoV-2 vaccination. Our results demonstrate a clear inactivation of the TRAF5 and TRAF6 genes when infection occurs after immunization, in contrast to infection without prior vaccination. This can bolster the belief that immunization is essential while also demonstrating the involvement of these molecules in the pathogenesis of SARS-CoV-2.

Ubiquitination of Hemocyanin Mediated by a Mitochondrial E3 Ubiquitin Ligase Regulates Immune Response in Penaeus vannamei

Ubiquitination is a critical posttranslational modification that regulates host immune responses to pathogens. In this study, we investigated the ubiquitination of hemocyanin (PvHMC [Penaeus vannamei hemocyanin]) mediated by the mitochondrial E3 ubiquitin ligase (PvMulan) in shrimp Penaeus vannamei. We characterized distinct ubiquitination patterns of PvHMC in response to different pathogen challenges, both in vitro and in vivo. Specifically, we found that Vibrio parahaemolyticus infection led to an increase in PvMulan, which resulted in K48-linked ubiquitination and subsequent proteasomal degradation of PvHMC. In contrast, PvMulan primarily enhanced the SUMOylation of PvHMC, bolstering its immune functions against white spot syndrome virus challenges. Inhibition of PvMulan-mediated PvHMC ubiquitination significantly affected the proliferation of V. parahaemolyticus and the survival rate of infected shrimps. This study sheds light on the role of hemocyanin ubiquitination in immune regulation, illustrating its dual function in response to distinct pathogens.

The Chlamydia trachomatis Inc Tri1 interacts with TRAF7 to displace native TRAF7 interacting partners

Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infections in the USA and of preventable blindness worldwide. This obligate intracellular pathogen replicates within a membrane-bound inclusion, but how it acquires nutrients from the host while avoiding detection by the innate immune system is incompletely understood. C. trachomatis accomplishes this in part through the translocation of a unique set of effectors into the inclusion membrane, the inclusion membrane proteins (Incs). Incs are ideally positioned at the host-pathogen interface to reprogram host signaling by redirecting proteins or organelles to the inclusion. Using a combination of co-affinity purification, immunofluorescence confocal imaging, and proteomics, we characterize the interaction between an early-expressed Inc of unknown function, Tri1, and tumor necrosis factor receptor-associated factor 7 (TRAF7). TRAF7 is a multi-domain protein with a RING finger ubiquitin ligase domain and a C-terminal WD40 domain. TRAF7 regulates several innate immune signaling pathways associated with C. trachomatis infection and is mutated in a subset of tumors. We demonstrate that Tri1 and TRAF7 specifically interact during infection and that TRAF7 is recruited to the inclusion. We further show that the predicted coiled-coil domain of Tri1 is necessary to interact with the TRAF7 WD40 domain. Finally, we demonstrate that Tri1 displaces the native TRAF7 binding partners, mitogen-activated protein kinase kinase kinase 2 (MEKK2), and MEKK3. Together, our results suggest that by displacing TRAF7 native binding partners, Tri1 has the capacity to alter TRAF7 signaling during C. trachomatis infection.IMPORTANCEChlamydia trachomatis is the leading cause of bacterial sexually transmitted infections in the USA and preventable blindness worldwide. Although easily treated with antibiotics, the vast majority of infections are asymptomatic and therefore go untreated, leading to infertility and blindness. This obligate intracellular pathogen evades the immune response, which contributes to these outcomes. Here, we characterize the interaction between a C. trachomatis-secreted effector, Tri1, and a host protein involved in innate immune signaling, TRAF7. We identified host proteins that bind to TRAF7 and demonstrated that Tri1 can displace these proteins upon binding to TRAF7. Remarkably, the region of TRAF7 to which these host proteins bind is often mutated in a subset of human tumors. Our work suggests a mechanism by which Tri1 may alter TRAF7 signaling and has implications not only in the pathogenesis of C. trachomatis infections but also in understanding the role of TRAF7 in cancer.

Insight into the role of IRF7 in skin and connective tissue diseases

Interferons (IFNs) are signalling proteins primarily involved in initiating innate immune responses against pathogens and promoting the maturation of immune cells. Interferon Regulatory Factor 7 (IRF7) plays a pivotal role in the IFNs signalling pathway. The activation process of IRF7 is incited by exogenous or abnormal nucleic acids, which is followed by the identification via pattern recognition receptors (PRRs) and the ensuing signalling cascades. Upon activation, IRF7 modulates the expression of both IFNs and inflammatory gene regulation. As a multifunctional transcription factor, IRF7 is mainly expressed in immune cells, yet its presence is also detected in keratinocytes, fibroblasts, and various dermal cell types. In these cells, IRF7 is critical for skin immunity, inflammation, and fibrosis. IRF7 dysregulation may lead to autoimmune and inflammatory skin conditions, including systemic scleroderma (SSc), systemic lupus erythematosus (SLE), Atopic dermatitis (AD) and Psoriasis. This comprehensive review aims to extensively elucidate the role of IRF7 and its signalling pathways in immune cells and keratinocytes, highlighting its significance in skin-related and connective tissue diseases.

The Chlamydia trachomatis Inc Tri1 interacts with TRAF7 to displace native TRAF7 interacting partners

Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infections in the US and of preventable blindness worldwide. This obligate intracellular pathogen replicates within a membrane-bound inclusion, but how it acquires nutrients from the host while avoiding detection by the innate immune system is incompletely understood. C. trachomatis accomplishes this in part through the translocation of a unique set of effectors into the inclusion membrane, the inc lusion membrane proteins (Incs). Incs are ideally positioned at the host-pathogen interface to reprogram host signaling by redirecting proteins or organelles to the inclusion. Using a combination of co-affinity purification, immunofluorescence confocal imaging, and proteomics, we characterize the interaction between an early-expressed Inc of unknown function, Tri1, and tumor necrosis factor receptor associated factor 7 (TRAF7). TRAF7 is a multi-domain protein with a RING finger ubiquitin ligase domain and a C-terminal WD40 domain. TRAF7 regulates several innate immune signaling pathways associated with C. trachomatis infection and is mutated in a subset of tumors. We demonstrate that Tri1 and TRAF7 specifically interact during infection and that TRAF7 is recruited to the inclusion. We further show that the predicted coiled-coil domain of Tri1 is necessary to interact with the TRAF7 WD40 domain. Finally, we demonstrate that Tri1 displaces the native TRAF7 binding partners, mitogen activated protein kinase kinase kinase 2 (MEKK2) and MEKK3. Together, our results suggest that by displacing TRAF7 native binding partners, Tri1 has the capacity to alter TRAF7 signaling during C. trachomatis infection.

Importance

Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infections in the US and preventable blindness worldwide. Although easily treated with antibiotics, the vast majority of infections are asymptomatic and therefore go untreated, leading to infertility and blindness. This obligate intracellular pathogen evades the immune response, which contributes to these outcomes. Here, we characterize the interaction between a C. trachomatis secreted effector, Tri1, and a host protein involved in innate immune signaling, TRAF7. We identified host proteins that bind to TRAF7 and demonstrate that Tri1 can displace these proteins upon binding to TRAF7. Remarkably, the region of TRAF7 to which these host proteins bind is often mutated in a subset of human tumors. Our work suggests a mechanism by which Tri1 may alter TRAF7 signaling and has implications not only in the pathogenesis of C. trachomatis infections, but also in understanding the role of TRAF7 in cancer.