Inhibition of ESCRT-independent extracellular vesicles biogenesis suppresses enterovirus 71 replication and pathogenesis in mice.

Enterovirus 71 (EV71) causes hand-foot-and-mouth disease (HFMD), neurological complications, and even fatalities in infants. Clinically, the increase of extracellular vesicles (EVs) in EV71 patients' serum was highly associated with the severity of HFMD. EV71 boosts EVs biogenesis in an endosomal sorting complex required for transport (ESCRT)-dependent manner to facilitate viral replication. Yet, the impact of EVs-derived from ESCRT-independent pathway on EV71 replication and pathogenesis is highly concerned. Here, we assessed the effects of EV71-induced EVs from ESCRT-independent pathway on viral replication and pathogenesis by GW4869, a neutral sphingomyelinase inhibitor. Detailly, in EV71-infected mice, blockade of the biogenesis of tissue-derived EVs in the presence of GW4869 restored body weight loss, attenuated clinical scores, and improved survival rates. Furthermore, GW4869 dampens EVs biogenesis to reduce viral load and pathogenesis in multiple tissues of EV71-infected mice. Consistently, GW4869 treatment in a human intestinal epithelial HT29 cells decreased the biogenesis of EVs, in which the progeny EV71 particle was cloaked, leading to the reduction of viral infection and replication. Collectively, GW4869 inhibits EV71-induced EVs in an ESCRT-independent pathway and ultimately suppresses EV71 replication and pathogenesis. Our study provides a novel strategy for the development of therapeutic agents in the treatment for EV71-associated HFMD.

Palmitoylation landscapes across human cancers reveal a role of palmitoylation in tumorigenesis.

BACKGROUND: Protein palmitoylation, which is catalyzed by palmitoyl-transferase and de-palmitoyl-transferase, plays a crucial role in various biological processes. However, the landscape and dynamics of protein palmitoylation in human cancers are not well understood. METHODS: We utilized 23 palmitoyl-acyltransferases and seven de-palmitoyl-acyltransferases as palmitoylation-related genes for protein palmitoylation analysis. Multiple publicly available datasets were employed to conduct pan-cancer analysis, examining the transcriptome, genomic alterations, clinical outcomes, and correlation with c-Myc (Myc) for palmitoylation-related genes. Real-time quantitative PCR and immunoblotting were performed to assess the expression of palmitoylation-related genes and global protein palmitoylation levels in cancer cells treated with Myc depletion or small molecule inhibitors. Protein docking and drug sensitivity analyses were employed to predict small molecules that target palmitoylation-related genes. RESULTS: We identified associations between palmitoylation and cancer subtype, stage, and patient survival. We discovered that abnormal DNA methylation and oncogenic Myc-driven transcriptional regulation synergistically contribute to the dysregulation of palmitoylation-related genes. This dysregulation of palmitoylation was closely correlated with immune infiltration in the tumor microenvironment and the response to immunotherapy. Importantly, dysregulated palmitoylation was found to modulate canonical cancer-related pathways, thus influencing tumorigenesis. To support our findings, we performed a proof-of-concept experiment showing that depletion of Myc led to reduced expression of most palmitoylation-related genes, resulting in decreased global protein palmitoylation levels. Through mass spectrometry and enrichment analyses, we also identified palmitoyl-acyltransferases ZDHHC7 and ZDHHC23 as significant contributors to mTOR signaling, DNA repair, and immune pathways, highlighting their potential roles in tumorigenesis. Additionally, our study explored the potential of three small molecular (BI-2531, etoposide, and piperlongumine) to modulate palmitoylation by targeting the expression or activity of palmitoylation-related genes or enzymes. CONCLUSIONS: Overall, our findings underscore the critical role of dysregulated palmitoylation in tumorigenesis and the response to immunotherapy, mediated through classical cancer-related pathways and immune cell infiltration. Additionally, we propose that the aforementioned three small molecule hold promise as potential therapeutics for modulating palmitoylation, thereby offering novel avenues for cancer therapy.

Zika virus non-structural protein 4B interacts with DHCR7 to facilitate viral infection.

Zika virus (ZIKV) evolves non-structural proteins to evade immune response and ensure efficient replication in the host cells. Cholesterol metabolic enzyme 7-dehydrocholesterol reductase (DHCR7) was recently reported to impact innate immune responses in ZIKV infection. However, the vital non-structural protein and mechanisms involved in DHCR7-mediated viral evasion are not well elucidated. In this study, we demonstrated that ZIKV infection facilitated DHCR7 expression. Notably, the upregulated DHCR7 in turn facilitated ZIKV infection and blocking DHCR7 suppressed ZIKV infection. Mechanically, ZIKV non-structural protein 4B (NS4B) interacted with DHCR7 to induce DHCR7 expression. Moreover, DHCR7 inhibited TANK-binding kinase 1 (TBK1) and interferon regulatory factor 3 (IRF3) phosphorylation, which resulted in the reduction of interferon-beta (IFN-ß) and interferon-stimulated genes (ISGs) productions. Therefore, we propose that ZIKV NS4B binds to DHCR7 to repress TBK1 and IRF3 activation, which in turn inhibits IFN-ß and ISGs, and thereby facilitating ZIKV evasion. This study broadens the insights on how viral non-structural proteins antagonize innate immunity to facilitate viral infection via cholesterol metabolic enzymes and intermediates.