Bredahlboye1635

Viruses have evolved diverse strategies to hijack the cellular gene expression system for their replication. The poly(A) binding proteins (PABPs), a family of critical gene expression factors, are viruses' common targets. PABPs act not only as a translation factor but also as a key factor of mRNA metabolism. During viral infections, the activities of PABPs are manipulated by various viruses, subverting the host translation machinery or evading the cellular antiviral defense mechanism. Viruses harness PABPs by modifying their stability, complex formation with other translation initiation factors, or subcellular localization to promote viral mRNAs translation while shutting off or competing with host protein synthesis. For the past decade, many studies have demonstrated the PABPs' roles during viral infection. This review summarizes a comprehensive perspective of PABPs' roles during viral infection and how viruses evade host antiviral defense through the manipulations of PABPs.Kobuviruses are an unusual and poorly characterized genus within the picornavirus family and can cause gastrointestinal enteric disease in humans, livestock, and pets. The human kobuvirus Aichi virus (AiV) can cause severe gastroenteritis and deaths in children below the age of 5 years; however, this is a very rare occurrence. During the assembly of most picornaviruses (e.g., poliovirus, rhinovirus, and foot-and-mouth disease virus), the capsid precursor protein VP0 is cleaved into VP4 and VP2. However, kobuviruses retain an uncleaved VP0. From studies with other picornaviruses, it is known that VP4 performs the essential function of pore formation in membranes, which facilitates transfer of the viral genome across the endosomal membrane and into the cytoplasm for replication. Here, we employ genome exposure and membrane interaction assays to demonstrate that pH plays a critical role in AiV uncoating and membrane interactions. We demonstrate that incubation at low pH alters the exposure of hydrophobic residuerange their capsids and induce membrane permeability in the absence of VP4. Here, we have used Aichi virus as a model VP0 virus to test for conservation of function between VP0 and VP4. This could enhance understanding of pore function and lead to development of novel therapeutic agents that block entry.Spleen tyrosine kinase (Syk) has recently come forth as a critical regulator of innate immune response. Previous studies identify Syk as a key kinase for STAT1 activation at the early stage of influenza A virus (IAV) infection that is involved in initial antiviral immunity. However, the involvement of Syk in host antiviral immunity during the late phase of IAV infection and its effect on pathogenesis of the virus remain unknown. Here, we found through time course studies that Syk restrained antiviral immune response at the late stage of IAV infection, thereby promoting viral replication. Depletion of Syk suppressed IAV replication in vitro, whereas ectopic expression of Syk facilitated viral replication. Moreover, Syk-deficient mice were employed, and we observed that knockout of Syk rendered mice more resistant to IAV infection, as evidenced by a lower degree of lung injury, slower body weight loss, and an increased survival rate of Syk knockout mice challenged with IAV. Furthermore, we revealed that Syk repd the expression of type I and III interferons, inhibited IAV replication, and rendered mice more resistant to IAV infection. Syk impaired innate immune signaling through impeding TBK1 activation. These data reveal that Syk participates in the initiation of antiviral defense against IAV infection and simultaneously contributes to the restriction of innate immunity at the late stage of viral infection, suggesting that Syk serves a dual function in regulating antiviral responses. This finding provides new insights into complicated mechanisms underlying interaction between virus and host immune system.The propagation of the hepatitis C virus (HCV) is regulated in part by the phosphorylation of its nonstructural protein NS5A that undergoes sequential phosphorylation on several highly conserved serine residues and switches from a hypo- to a hyperphosphorylated state. Previous studies have shown that NS5A sequential phosphorylation requires NS3 encoded on the same NS3-NS4A-NS4B-NS5A polyprotein. Subtle mutations in NS3 without affecting its protease activity could affect NS5A phosphorylation. Given the ATPase domain in the NS3 COOH terminus, we tested whether NS3 participates in NS5A phosphorylation similarly to the nucleoside diphosphate kinase-like activity of the rotavirus NSP2 nucleoside triphosphatase (NTPase). Mutations in the NS3 ATP-binding motifs blunted NS5A hyperphosphorylation and phosphorylation at serines 225, 232, and 235, whereas a mutation in the RNA-binding domain did not. The phosphorylation events were not rescued with wild-type NS3 provided in trans. When provided with an NS3 ATPase-compaein kinase Iα is a very potent kinase responsible for NS5A phosphorylation at serines 225, 232, and 235. Our data suggest that ATP binding by NS3 probably results in conformational changes that recruit casein kinase Iα to phosphorylate NS5A, initially at S225 and subsequently at S232 and S235. Our discovery reveals intricate requirements of the structural integrity of NS3 for NS5A hyperphosphorylation and HCV replication.The "shock and kill" strategy for HIV-1 cure incorporates latency-reversing agents (LRA) in combination with interventions that aid the host immune system in clearing virally reactivated cells. LRAs have not yet been investigated in pediatric clinical or preclinical studies. Here, we evaluated an inhibitor of apoptosis protein (IAP) inhibitor (IAPi), AZD5582, that activates the noncanonical NF-κB (ncNF-κB) signaling pathway to reverse latency. Ten weekly doses of AZD5582 were intravenously administered at 0.1 mg/kg to rhesus macaque (RM) infants orally infected with SIVmac251 at 4 weeks of age and treated with a triple ART regimen for over 1 year. During AZD5582 treatment, on-ART viremia above the limit of detection (LOD, 60 copies/mL) was observed in 5/8 infant RMs starting at 3 days post-dose 4 and peaking at 771 copies/mL. Of the 135 measurements during AZD5582 treatment in these 5 RM infants, only 8 were above the LOD (6%), lower than the 46% we have previously reported in adult RMs. Pharmacokinetic analyvaluate AZD5582, identified as a potent latency-reversing agent in adult macaques, in the controlled setting of daily ART. We demonstrated the safety of the IAPi AZD5582 and evaluate the pharmacokinetics and pharmacodynamics of repeated dosing. The response to AZD5582 in macaque infants differed from what we previously showed in adult macaques with weaker latency reversal in infants, likely due to altered pharmacokinetics and less inducibility of infant CD4+ T cells. These data supported the contention that HIV-1 cure strategies for children are best evaluated using pediatric model systems.Colorectal cancer (CRC) is a common malignant tumor with high morbidity and mortality, and significant heterogeneity among patients. In this study, we aimed to explore the role and mechanism of CLK2 in CRC, a kinase that phosphorylates SR proteins involved in splicing. Based on the analysis from The Cancer Genome Atlas (TCGA) dataset and tissue microarray, we found that CLK2 was upregulated in CRC tissues and associated with a higher tumor stage and poorer overall survival. Consistent with the bioinformatics analysis, the functional experiments validated that CLK2 acted as a tumor-promoting factor in CRC progression. CLK2 knockdown suppressed aggressive cell proliferation, migration, and invasion in vitro, as well as restrained tumor growth in vivo. In terms of mechanism, we found that the Wnt/β-catenin signaling pathway was responsible for the CLK2-induced CRC progression, based on the results of pathway enrichment analysis and subsequent experimental validation. Thus, our study, for the first time, identified the role of CLK2 in CRC development and provided a compelling biomarker for targeted therapy in CRC treatment.Colon cancer is a common cause of death in the world, and its main cause of therapy failure is chemoresistance. Apoptosis is de-regulated in colon cancer and is one key mechanism of cancer treatment. We recently reported that reduced expression of ARHGAP17, a Rho GTPase activating protein, correlated with a poor prognosis of colon cancer patients. Here we investigated the role of ARHGAP17 in apoptosis induced by 5-fluorouracil (5-FU) in human colon cancer cells and in mouse xenograft tumor model. We observed a decreased protein level of ARHGAP17 in 5-FU resistant colon cancer cells (HCT116/5-FU and HCT8/5-FU). While ARHGAP17 knockdown attenuated apoptosis upon 5-FU treatment in HCT116 and HCT8, and ARHGAP17 overexpression in HCT116/5-FU and HCT8/5-FU cells increased apoptosis induced by 5-FU. We also found that ARHGAP17 knockdown led to a high level of active Rac1 in HCT116 and HCT8, but ARHGAP17 overexpression reduced active Rac1 in HCT116/5-FU and HCT8/5-FU cells. However, Rac1 inhibitor abolished the effect of ARHGAP17 knockdown, and Rac1 overexpression diminished the effect of ARHGAP17 overexpression on apoptosis induced by 5-FU. check details Apoptosis was also confirmed by cleaved Caspase-3 and cleaved PARP. Further, we observed that overexpression of ARHGAP17 promoted 5-FU-induced apoptosis and attenuated tumor growth in vivo. Collectively, our data indicate that ARHGAP17 sensitizes chemotherapy-resistant colon cancer cells to apoptosis induced by 5-FU, which is in part through suppressing Rac1.CMTM6 is a major regulator of PD-L1 expression. Aberrant Wnt pathway signaling occurs in most sporadic colorectal cancers (CRC). However, the significance and correlation of β-catenin, CMTM6, and PD-L1 immunohistochemical expression in CRC is still unknown and need to be further verified. We evaluated the expression levels of β-catenin, CMTM6, PD-L1, and MMR (mismatch repair) proteins by immunohistochemistry in CRC tissue microarray (TMA), and evaluated the association among β-catenin, CMTM6, PD-L1 expression, MMR status, and clinicopathological features in 704 CRC patients. Positive expression of PD-L1 in tumor cells (TC) is associated with more frequent dMMR (mismatch repair deficient) status, CMTM6 expression, right colon, and younger CRC patients. The expression of PD-L1 in tumor-infiltrating immune cells (IC) is associated with a higher frequency of adenocarcinoma, β-catenin, and CMTM6 expression. In univariate analysis, age, histological subtype, histologic grade, lymphatic metastasis, TNM stage, MMR status, and expression of PD-L1 protein in IC were significantly associated with the overall survival. In multivariate analysis, age, histologic grade, TNM stage, MMR status, and expression of PD-L1 protein in IC were independent prognostic factors. The overall survival of the adjuvant chemotherapy group was significantly higher than those non-chemotherapy in TNM stage III-IV CRC patients, but no significant overall survival improvement was found in the positive PD-L1 in TC, positive PD-L1 in IC, positive CMTM6, low β-catenin expression, or dMMR status subgroups. Expression of CMTM6 and PD-L1 in CRC are positively associated with β-catenin and reliable biomarkers for the prediction of responding to chemotherapy. The expression of β-catenin/CMTM6/PD-L1 and MMR status may be valuable biomarkers for guiding different treatment strategies in CRC patients.