HSP90 inhibitors 17-AAG and VER-82576 inhibit porcine deltacoronavirus replication in vitro

Novel interacting proteins identified by tandem affinity purification and mass spectrometry associated with IFITM3 protein during PDCoV infection

Interferon-induced transmembrane 3 (IFITM3) is a membrane-associated protein that exhibits antiviral activities against a wide range of viruses through interactions with other cellular and viral proteins. However, knowledge of the mechanisms of IFITM3 in Porcine deltacoronavirus (PDCoV) infection has been lacking. In this study, we demonstrate that IFN-α treatment induces the upregulation of IFITM3 activity and thus attenuates PDCoV infection. PDCoV replication is inhibited in a dose-dependent manner by IFITM3 overexpression. To clarify the novel roles of IFITM3 during PDCoV infection, proteins that interact with IFITM3 were screened by TAP/MS in an ST cell line stably expressing IFITM3 via a lentivirus. We identified known and novel candidate IFITM3-binding proteins and analyzed the protein complexes using GO annotation, KEGG pathway analysis, and protein interaction network analysis. A total of 362 cellular proteins associate with IFITM3 during the first 24 h post-infection. Of these proteins, the relationship between IFITM3 and Rab9a was evaluated by immunofluorescence colocalization analysis using confocal microscopy. IFITM3 partially colocalized with Rab9a and Rab9a exhibited enhanced colocalization following PDCoV infection. We also demonstrated that IFITM3 interacts specifically with Rab9a. Our results considerably expand the protein networks of IFITM3, suggesting that IFITM3 participates in multiple cellular processes during PDCoV infection.

Heat shock protein 90: biological functions, diseases, and therapeutic targets

Heat shock protein 90 (Hsp90) is a predominant member among Heat shock proteins (HSPs), playing a central role in cellular protection and maintenance by aiding in the folding, stabilization, and modification of diverse protein substrates. It collaborates with various co-chaperones to manage ATPase-driven conformational changes in its dimer during client protein processing. Hsp90 is critical in cellular function, supporting the proper operation of numerous proteins, many of which are linked to diseases such as cancer, Alzheimer's, neurodegenerative conditions, and infectious diseases. Recognizing the significance of these client proteins across diverse diseases, there is a growing interest in targeting Hsp90 and its co-chaperones for potential therapeutic strategies. This review described biological background of HSPs and the structural characteristics of HSP90. Additionally, it discusses the regulatory role of heat shock factor-1 (HSF-1) in modulating HSP90 and sheds light on the dynamic chaperone cycle of HSP90. Furthermore, the review discusses the specific contributions of HSP90 in various disease contexts, especially in cancer. It also summarizes HSP90 inhibitors for cancer treatment, offering a thoughtful analysis of their strengths and limitations. These advancements in research expand our understanding of HSP90 and open up new avenues for considering HSP90 as a promising target for therapeutic intervention in a range of diseases.

HSP90AB1 is a host factor that promotes porcine deltacoronavirus replication

Porcine deltacoronavirus (PDCoV) is an emerging enteropathogenic coronavirus. It causes mortality in neonatal piglets and is of growing concern because of its broad host range, including humans. To date, the mechanism of PDCoV infection remains poorly understood. Here, based on a genome-wide CRISPR screen of PDCoV-infected cells, we found that HSP90AB1 (heat shock protein 90 alpha family class B1) promotes PDCoV infection. Knockdown or KO of HSP90AB1 in LLC-PK cells resulted in a significantly suppressed PDCoV infection. Infected cells treated with HSP90 inhibitors 17-AAG and VER-82576 also showed a significantly suppressed PDCoV infection, although KW-2478, which does not affect the ATPase activity of HSP90AB1, had no effect on PDCoV infection. We found that HSP90AB1 interacts with the N, NS7, and NSP10 proteins of PDCoV. We further evaluated the interaction between N and HSP90AB1 and found that the C-tail domain of the N protein is the HSP90AB1-interacting domain. Further studies showed that HSP90AB1 protects N protein from degradation via the proteasome pathway. In summary, our results reveal a key role for HSP90AB1 in the mechanism of PDCoV infection and contribute to provide new host targets for PDCoV antiviral research.

HSP90AB1 Is a Host Factor Required for Transmissible Gastroenteritis Virus Infection

Transmissible gastroenteritis virus (TGEV) is an important swine enteric coronavirus causing viral diarrhea in pigs of all ages. Currently, the development of antiviral agents targeting host proteins to combat viral infection has received great attention. The heat shock protein 90 (HSP90) is a critical host factor and has important regulatory effects on the infection of various viruses. However, its roles in porcine coronavirus infection remain unclear. In this study, the effect of HSP90 on TGEV infection was evaluated. In addition, the influence of its inhibitor VER-82576 on proinflammatory cytokine (IL-6, IL-12, TNF-α, CXCL10, and CXCL11) production induced by TGEV infection was further analyzed. The results showed that the knockdown of HSP90AB1 and HSP90 inhibitor VER-82576 treatment resulted in a reduction in TGEV M gene mRNA levels, the N protein level, and virus titers in a dose-dependent manner, while the knockdown of HSP90AA1 and KW-2478 treatment had no significant effect on TGEV infection. A time-of-addition assay indicated that the inhibitory effect of VER-82576 on TGEV infection mainly occurred at the early stage of viral replication. Moreover, the TGEV-induced upregulation of proinflammatory cytokine (IL-6, IL-12, TNF-α, CXCL10, and CXCL11) expression was significantly inhibited by VER-82576. In summary, these findings indicated that HSP90AB1 is a host factor enhancing TGEV infection, and the HSP90 inhibitor VER-82576 could reduce TGEV infection and proinflammatory cytokine production, providing a new perspective for TGEV antiviral drug target design.

Host cell stress response as a predictor of COVID-19 infectivity and disease progression

The coronavirus disease (COVID-19) caused by a coronavirus identified in December 2019 has caused a global pandemic. COVID-19 was declared a pandemic in March 2020 and has led to more than 6.3 million deaths. The pandemic has disrupted world travel, economies, and lifestyles worldwide. Although vaccination has been an effective tool to reduce the severity and spread of the disease there is a need for more concerted approaches to fighting the disease. COVID-19 is characterised as a severe acute respiratory syndrome . The severity of the disease is associated with a battery of comorbidities such as cardiovascular diseases, cancer, chronic lung disease, and renal disease. These underlying diseases are associated with general cellular stress. Thus, COVID-19 exacerbates outcomes of the underlying conditions. Consequently, coronavirus infection and the various underlying conditions converge to present a combined strain on the cellular response. While the host response to the stress is primarily intended to be of benefit, the outcomes are occasionally unpredictable because the cellular stress response is a function of complex factors. This review discusses the role of the host stress response as a convergent point for COVID-19 and several non-communicable diseases. We further discuss the merits of targeting the host stress response to manage the clinical outcomes of COVID-19.

A Comparative Transcriptomic Analysis Reveals That HSP90AB1 Is Involved in the Immune and Inflammatory Responses to Porcine Deltacoronavirus Infection

PDCoV is an emerging enteropathogenic coronavirus that mainly causes acute diarrhea in piglets, seriously affecting pig breeding industries worldwide. To date, the molecular mechanisms of PDCoV-induced immune and inflammatory responses or host responses in LLC-PK cells in vitro are not well understood. HSP90 plays important roles in various viral infections. In this study, HSP90AB1 knockout cells (HSP90AB1^KO) were constructed and a comparative transcriptomic analysis between PDCoV-infected HSP90AB1^WT and HSP90AB1^KO cells was conducted using RNA sequencing to explore the effect of HSP90AB1 on PDCoV infection. A total of 1295 and 3746 differentially expressed genes (DEGs) were identified in PDCoV-infected HSP90AB1^WT and HSP90AB1^KO cells, respectively. Moreover, most of the significantly enriched pathways were related to immune and inflammatory response-associated pathways upon PDCoV infection. The DEGs enriched in NF-κB pathways were specifically detected in HSP90AB1^WT cells, and NF-κB inhibitors JSH-23, SC75741 and QNZ treatment reduced PDCoV infection. Further research revealed most cytokines associated with immune and inflammatory responses were upregulated during PDCoV infection. Knockout of HSP90AB1 altered the upregulated levels of some cytokines. Taken together, our findings provide new insights into the host response to PDCoV infection from the transcriptome perspective, which will contribute to illustrating the molecular basis of the interaction between PDCoV and HSP90AB1.