Characterization of the RNA-binding properties of the triple-gene-block protein 2 of Bamboo mosaic virus

The triple-gene-block protein 2 (TGBp2) of Bamboo mosaic virus (BaMV) is a transmembrane protein which was proposed to be involved in viral RNA binding during virus transport. Here, we report on the RNA-binding properties of TGBp2. Using tyrosine fluorescence spectroscopy and UV-crosslinking assays, the TGBp2 solubilized with Triton X-100 was found to interact with viral RNA in a non-specific manner. These results raise the possibility that TGBp2 facilitates intracellular delivery of viral RNA through non-specific protein-RNA interaction

Change in insulin resistance according to virological response during antiviral treatment for hepatitis C virus infection

SummaryBackgroundHepatitis C virus (HCV) infection can lead to increased insulin resistance, but the dynamics of insulin resistance in HCV-infected patients receiving pegylated interferon plus ribavirin remain elusive.MethodsThis prospective study enrolled HCV-infected patients who received pegylated interferon plus ribavirin. Patients were classified according to the attainment of sustained virological response (SVR). Insulin resistance was measured using homeostatic model assessment-insulin resistance (HOMA-IR). The change in HOMA-IR at baseline, the end of treatment, and 24 weeks after the end of treatment was compared in patients who achieved SVR and those who did not.ResultsA total of 65 patients participated in this study, of which 46 (71%) achieved SVR. Overall, The HOMA-IR changed significantly during antiviral therapy, with the median values [interquartile range (IQR)] of 3.7 (1.6–10.0) prior to the treatment, 1.5 (0.8–2.9) at the end, and 1.6 (0.9–3.1) at 24 weeks after completion of therapy. However, only patients who achieved SVR had significant off-therapy reduction of HOMA-IR, with median values of 1.3 (IQR, 0.7–2.6) at 24 weeks off therapy and 3.6 (IQR, 1.5–9.9) at baseline (p < 0.0001). In those without SVR, the HOMA-IR measured 24 weeks after treatment completion (median, 2.2; IQR, 1.9–4.7) did not differ from baseline values (median, 3.9; IQR, 2.2–10.0; p = 0.5).ConclusionDual therapy with pegylated interferon plus ribavirin ameliorated IR in HCV-infected patients, but the off-therapy improvement of IR was limited to those who attained SVR

The Stable Association of Virion with the Triple-geneblockProtein 3-based Complex of Bamboo mosaic virus

The triple-gene-block protein 3 (TGBp3) of Bamboo mosaic virus (BaMV) is an integral endoplasmic reticulum (ER) membraneprotein which is assumed to form a membrane complex to deliver the virus intracellularly. However, the virus entity that isdelivered to plasmodesmata (PD) and its association with TGBp3-based complexes are not known. Results from chemicalextraction and partial proteolysis of TGBp3 in membrane vesicles revealed that TGBp3 has a right-side-out membranetopology; i.e., TGBp3 has its C-terminal tail exposed to the outer surface of ER. Analyses of the TGBp3-specificimmunoprecipitate of Sarkosyl-extracted TGBp3-based complex revealed that TGBp1, TGBp2, TGBp3, capsid protein (CP),replicase and viral RNA are potential constituents of virus movement complex. Substantial co-fractionation of TGBp2, TGBp3and CP, but not TGBp1, in the early eluted gel filtration fractions in which virions were detected after TGBp3-specificimmunoprecipitation suggested that the TGBp2- and TGBp3-based complex is able to stably associate with the virion. Thisnotion was confirmed by immunogold-labeling transmission electron microscopy (TEM) of the purified virions. In addition,mutational and confocal microscopy analyses revealed that TGBp3 plays a key role in virus cell-to-cell movement byenhancing the TGBp2- and TGBp3-dependent PD localization of TGBp1. Taken together, our results suggested that the cellto-cell movement of potexvirus requires stable association of the virion cargo with the TGBp2- and TGBp3-based membranecomplex and recruitment of TGBp1 to the PD by this complex

Periodontal pathogens are a risk factor of oral cavity squamous cell carcinoma, independent of tobacco and alcohol and human papillomavirus

Over the past decade, there has been a change in the epidemiology of oral cavity squamous cell cancer (OC-SCC). Many new cases of OC-SCC lack the recognized risk factors of smoking, alcohol and human papilloma virus. The aim of this study was to determine if the oral microbiome may be associated with OC-SCC in nonsmoking HPV negative patients. We compared the oral microbiome of HPV-negative nonsmoker OC-SCC(n = 18), premalignant lesions(PML) (n = 8) and normal control patients (n = 12). Their oral microbiome was sampled by oral wash and defined by 16S rRNA gene sequencing. We report that the periodontal pathogens Fusobacterium, Prevotella, Alloprevotella were enriched while commensal Streptococcus depleted in OC-SCC. Based on the four genera plus a marker genus Veillonella for PML, we classified the oral microbiome into two types. Gene/pathway analysis revealed a progressive increase of genes encoding HSP90 and ligands for TLRs 1, 2 and 4 along the controls→PML → OC-SCC progression sequence. Our findings suggest an association between periodontal pathogens and OC-SCC in non smoking HPV negative patients

2-Deoxy-D-glucose enhances TRAIL-induced apoptosis in human melanoma cells through XBP-1-mediated up-regulation of TRAIL-R2

Background: Past studies have shown that sensitivity of melanoma cells to TRAIL-induced apoptosis is largely correlated with the expression levels of TRAIL death receptors on the cell surface. However, fresh melanoma isolates and melanoma tissue sections express generally low levels of death receptors for TRAIL. The clinical potential of TRAIL in the treatment of melanoma may therefore be limited unless given with agents that increase the cell surface expression of TRAIL death receptors. 2-Deoxy-D-glucose (2-DG) is a synthetic glucose analogue that inhibits glycolysis and glycosylation and blocks cell growth. It has been in clinical evaluation for its potential use as an anticancer agent. In this study, we have examined whether 2-DG and TRAIL interact to enhance their cytotoxicity towards melanoma cells. Results: 2-DG did not kill melanoma cells, but enhanced TRAIL-induced apoptosis in cultured melanoma cells and fresh melanoma isolates. This was associated with increased activation of the caspase cascade and mitochondrial apoptotic pathway, and was blocked by inhibition of TRAIL-R2, and to a lesser extent, inhibition of TRAIL-R1. Treatment with 2-DG up-regulated TRAIL death receptors, in particular, TRAIL-R2, on the melanoma cell surface. Up-regulation of TRAIL-R2 was due to increased transcription that was not dependent on the transcription factors, p53 and CHOP. Instead, the IRE1α and ATF6 pathways of the unfolded protein response that were activated by 2-DG appeared to be involved. Moreover, XBP-1, which is known to be transcriptionally regulated by ATF6 and functionally activated by IRE1α, was found to play an important role in 2-DG-mediated transcriptional up-regulation of TRAIL-R2 in melanoma cells. Conclusion: These results indicate that 2-DG sensitizes human melanoma cells to TRAIL-induced apoptosis by up-regulation of TRAIL-2 via the ATF6/IRE1α/XBP-1 axis of the unfolded protein response. They suggest that 2-DG is a promising agent to increase the therapeutic response to TRAIL in melanoma

Binding of ATP to the CBS domains in the C-terminal region of CLC-1

The common gating of CLC-1 has been shown to be inhibited by intracellular adenosine triphosphate (ATP) in acidic pH conditions. Such modulation is thought to be mediated by direct binding of ATP to the cystathionine β-synthase (CBS) domains at the C-terminal cytoplasmic region of CLC-1. Guided by the crystal structure of the C-terminal domain of CLC-5, we constructed a homology model of CLC-1’s C terminus and mutated critical amino acid residues lining the potential ATP-binding site. The CLC-1 mutations V634A and E865A completely abolished the ATP inhibition of CLC-1, consistent with the loss of ATP binding seen with the corresponding mutations in CLC-5. Mutating two other residues, V613 and V860, also disrupted the ATP modulation of CLC-1. However, placing aromatic amino acids at position 634 increases the apparent ATP affinity. Mutant cycle analyses showed that the modulation effects of ATP and cytidine triphosphate on wild-type CLC-1 and the V634F mutant were nonadditive, suggesting that the side chain of amino acid at position 634 interacts with the base moiety of the nucleotide. The mutation effects of V634F and V613A on the ATP modulation were also nonadditive, which is consistent with the assertion suggested from the homology model that these two residues may both interact with the bound nucleotide. These results provide evidence for a direct ATP binding for modulating the function of CLC-1 and suggest an overall conserved architecture of the ATP-binding sites in CLC-1 and CLC-5. This study also demonstrates that CLC-1 is a convenient experimental model for studying the interaction of nucleotides/nucleosides with the CBS domain