Description: One-half of the genes in the human genome contain alternative promoters, some of which generate products with opposing functions. Aberrant silencing or activation of such alternative promoters is associated with multiple diseases, including cancer, but little is known regarding the molecular mechanisms that control alternative promoter choice. The SHC1 gene encodes p46 Shc /p52 Shc and p66 Shc , proteins oppositely regulating anchorage-independent growth that are produced by transcription initiated from the upstream and downstream tandem promoters of SHC1 , respectively. Here we demonstrate that activation of these promoters is mutually exclusive on separate alleles in single primary endothelial cells in a heritable fashion, ensuring expression of both transcripts by the cell. Peripheral blood lymphocytes that do not transcribe p66 Shc transcribed p52 Shc biallelically. This distinct monoallelic transcription pattern is established by allele-specific chromosomal looping between tandem promoters, which silences the upstream promoter. Our results reveal a new mechanism to control alternative promoter usage through higher-order chromatin structure.

Description: IL-17, a major inflammatory cytokine plays a critical role in the pathogenesis of many autoimmune inflammatory diseases. In this study, we report a new function of RNA-binding protein HuR in IL-17–induced Act1-mediated chemokine mRNA stabilization. HuR deficiency markedly reduced IL-17–induced chemokine expression due to increased mRNA decay. Act1-mediated HuR polyubiquitination was required for the binding of HuR to CXCL1 mRNA, leading to mRNA stabilization. Although IL-17 induced the coshift of Act1 and HuR to the polysomal fractions in a sucrose gradient, HuR deficiency reduced the ratio of translation-active/translation-inactive IL-17–induced chemokine mRNAs. Furthermore, HuR deletion in distal lung epithelium attenuated IL-17–induced neutrophilia. In summary, HuR functions to couple receptor-proximal signaling to posttranscriptional machinery, contributing to IL-17–induced inflammation.

Description: Due to enzootic infections in poultry and persistent human infections in China, influenza A (H7N9) virus has remained a public health threat. The Yangtze River Delta region, which is located in eastern China, is well recognized as the original source for H7N9 outbreaks. Based on the evolutionary analysis of H7N9 viruses from all three outbreak waves since 2013, we identified the Pearl River Delta region as an additional H7N9 outbreak source. H7N9 viruses are repeatedly introduced from these two sources to the other areas, and the persistent circulation of H7N9 viruses occurs in poultry, causing continuous outbreak waves. Poultry movements may contribute to the geographic expansion of the virus. In addition, the AnH1 genotype, which was predominant during wave 1, was replaced by JS537, JS18828, and AnH1887 genotypes during waves 2 and 3. The establishment of a new source and the continuous evolution of the virus hamper the elimination of H7N9 viruses, thus posing a long-term threat of H7N9 infection in humans. Therefore, both surveillance of H7N9 viruses in humans and poultry and supervision of poultry movements should be strengthened. IMPORTANCE Since its occurrence in humans in eastern China in spring 2013, the avian H7N9 viruses have been demonstrating the continuing pandemic threat posed by the current influenza ecosystem in China. As the viruses are silently circulated in poultry, with potentially severe outcomes in humans, H7N9 virus activity in humans in China is very important to understand. In this study, we identified a newly emerged H7N9 outbreak source in the Pearl River Delta region. Both sources in the Yangtze River Delta region and the Pearl River Delta region have been established and found to be responsible for the H7N9 outbreaks in mainland China.

Description: Epstein-Barr virus (EBV) is a ubiquitous gammaherpesvirus that is highly prevalent in almost all human populations and is associated with many human cancers, such as nasopharyngeal carcinoma (NPC), Hodgkin's disease, and gastric carcinoma. However, in these EBV-associated cancers, only NPC exhibits remarkable ethnic and geographic distribution. We hypothesized that EBV genomic variations might contribute to the pathogenesis of different human cancers in different geographic areas. In this study, we collected 18 NPC biopsy specimens from the Hunan Province in southern China and de novo assembled 18 NPC biopsy specimen-derived EBV (NPC-EBV) genomes, designated HN1 to HN18. This was achieved through target enrichment of EBV DNA by hybridization, followed by next-generation sequencing, to reveal sequence diversity. These EBV genomes harbored 20,570 variations totally, including 20,328 substitutions, 88 insertions, and 154 deletions, compared to the EBV reference genome. Phylogenetic analysis revealed that all NPC-EBV genomes were distinct from other EBV genomes. Furthermore, HN1 to HN18 had some nonsynonymous variations in EBV genes including genes encoding latent, early lytic, and tegument proteins, such as substitutions within transmembrane domains 1 and 3 of LMP1, FoP_duplication, and zf-AD domains of ENBA1, in addition to aberrations in noncoding regions, especially in BamHI A rightward transcript microRNAs. These variations might have potential biological significance. In conclusion, we reported a genome-wide view of sequence variation in EBV isolated from primary NPC biopsy specimens obtained from the Hunan Province. This might contribute to further understanding of how genomic variations contribute to carcinogenesis, which would impact the treatment of EBV-associated cancer. IMPORTANCE Nasopharyngeal carcinoma (NPC) is highly associated with Epstein-Barr virus (EBV) infection and exhibits remarkable ethnic and geographic distribution. Hunan Province in southern China has a high incidence rate of NPCs. Here, we report 18 novel EBV genome sequences from viruses isolated from primary NPC biopsy specimens in this region, revealing whole-genome sequence diversity.

Description: Infectious bursal disease (IBD) is an acute, highly contagious, and immunosuppressive avian disease caused by IBD virus (IBDV). Although IBDV-induced immunosuppression has been well established, the underlying exact molecular mechanism for such induction is not very clear. We report here the identification of IBDV VP4 as an interferon suppressor by interaction with the glucocorticoid-induced leucine zipper (GILZ) in host cells. We found that VP4 suppressed the expression of type I interferon in HEK293T cells after tumor necrosis factor alpha (TNF-α) treatment or Sendai virus (SeV) infection and in DF-1 cells after poly(I·C) stimulation. In addition, the VP4-induced suppression of type I interferon could be completely abolished by knockdown of GILZ by small interfering RNA (siRNA). Furthermore, knockdown of GILZ significantly inhibited IBDV growth in host cells, and this inhibition could be markedly mitigated by anti-alpha/beta interferon antibodies in the cell cultures ( P 〈 0.001). Thus, VP4-induced suppression of type I interferon is mediated by interaction with GILZ, a protein that appears to inhibit cell responses to viral infection.

Description: Pneumonia is one of the most prevalent Staphylococcus aureus -mediated diseases, and the treatment of this infection is becoming challenging due to the emergence of multidrug-resistant S. aureus , especially methicillin-resistant S. aureus (MRSA) strains. It has been reported that LysGH15, the lysin derived from phage GH15, displays high efficiency and a broad lytic spectrum against MRSA and that apigenin can markedly diminish the alpha-hemolysin of S. aureus . In this study, the combination therapy of LysGH15 and apigenin was evaluated in vitro and in a mouse S. aureus pneumonia model. No mutual adverse influence was detected between LysGH15 and apigenin in vitro . In animal experiments, the combination therapy showed a more effective treatment effect than LysGH15 or apigenin monotherapy ( P 〈 0.05). The bacterial load in the lungs of mice administered the combination therapy was 1.5 log units within 24 h after challenge, whereas the loads in unprotected mice or mice treated with apigenin or LysGH15 alone were 10.2, 4.7, and 2.6 log units, respectively. The combination therapy group showed the best health status, the lowest ratio of wet tissue to dry tissue of the lungs, the smallest amount of total protein and cells in the lung, the fewest pathological manifestations, and the lowest cytokine level compared with the other groups ( P 〈 0.05). With regard to its better protective efficacy, the combination therapy of LysGH15 and apigenin exhibits therapeutic potential for treating pneumonia caused by MRSA. This paper reports the combination therapy of lysin and natural products derived from traditional Chinese medicine.

Description: Inorganic arsenic is a well-documented human carcinogen associated with cancers of the skin, lung, liver, and bladder. However, the underlying mechanisms explaining the tumorigenic role of arsenic are not well understood. The present study explored a potential mechanism of cell transformation induced by arsenic exposure. Exposure to a low dose (0.5 μm) of arsenic trioxide (As2O3) caused transformation of BALB/c 3T3 cells. In addition, in a xenograft mouse model, tumor growth of the arsenic-induced transformed cells was dramatically increased. In arsenic-induced transformed cells, polycomb group (PcG) proteins, including BMI1 and SUZ12, were activated resulting in enhanced histone H3K27 tri-methylation levels. On the other hand, tumor suppressor p16INK4a and p19ARF mRNA and protein expression were dramatically suppressed. Introduction of small hairpin (sh) RNA-BMI1 or -SUZ12 into BALB/c 3T3 cells resulted in suppression of arsenic-induced transformation. Histone H3K27 tri-methylation returned to normal in BMI1- or SUZ12-knockdown BALB/c 3T3 cells compared with BMI1- or SUZ12-wildtype cells after arsenic exposure. As a consequence, the expression of p16INK4a and p19ARF was recovered in arsenic-treated BMI1- or SUZ12-knockdown cells. Thus, arsenic-induced cell transformation was blocked by inhibition of PcG function. Taken together, these results strongly suggest that the polycomb proteins, BMI1 and SUZ12 are required for cell transformation induced by organic arsenic exposure.

Description: BMP2 (bone morphogenetic protein 2) is known to activate unfolded protein response signaling molecules, including XBP1S and ATF6. However, the influence on XBP1S and ATF6 in BMP2-induced chondrocyte differentiation has not yet been elucidated. In this study, we demonstrate that BMP2 mediates mild endoplasmic reticulum stress-activated ATF6 and directly regulates XBP1S splicing in the course of chondrogenesis. XBP1S is differentially expressed during BMP2-stimulated chondrocyte differentiation and exhibits prominent expression in growth plate chondrocytes. This expression is probably due to the activation of the XBP1 gene by ATF6 and splicing by IRE1a. ATF6 directly binds to the 5′-flanking regulatory region of the XBP1 gene at its consensus binding elements. Overexpression of XBP1S accelerates chondrocyte hypertrophy, as revealed by enhanced expression of type II collagen, type X collagen, and RUNX2; however, knockdown of XBP1S via the RNAi approach abolishes hypertrophic chondrocyte differentiation. In addition, XBP1S associates with RUNX2 and enhances RUNX2-induced chondrocyte hypertrophy. Altered expression of XBP1S in chondrocyte hypertrophy was accompanied by altered levels of IHH (Indian hedgehog) and PTHrP (parathyroid hormone-related peptide). Collectively, XBP1S may be a novel regulator of hypertrophic chondrocyte differentiation by 1) acting as a cofactor of RUNX2 and 2) affecting IHH/PTHrP signaling.

Description: The human ether-a-go-go-related gene (hERG) encodes the rapidly activating delayed rectifier potassium channel (IKr) which plays an important role in cardiac repolarization. A reduction or increase in hERG current can cause long or short QT syndrome, respectively, leading to fatal cardiac arrhythmias. The channel density in the plasma membrane is a key determinant of the whole cell current amplitude. To gain insight into the molecular mechanisms for the regulation of hERG density at the plasma membrane, we used whole cell voltage clamp, Western blotting, and immunocytochemical methods to investigate the effects of an integral membrane protein, caveolin-3 (Cav3) on hERG expression levels. Our data demonstrate that Cav3, hERG, and ubiquitin-ligase Nedd4-2 interact with each other and form a complex. Expression of Cav3 thus enhances the hERG-Nedd4-2 interaction, leading to an increased ubiquitination and degradation of mature, plasma-membrane localized hERG channels. Disrupting Nedd4-2 interaction with hERG by mutations eliminates the effects of Cav3 on hERG channels. Knockdown of endogenous Cav3 or Nedd4-2 in cultured neonatal rat ventricular myocytes using siRNA led to an increase in native IKr. Our data demonstrate that hERG expression in the plasma membrane is regulated by Cav3 via Nedd4-2. These findings extend our understanding of the regulation of hERG channels and cardiac electrophysiology.

Description: A/duck/Shanghai/28-1/2009(H4N2) (DK28) was isolated from a live poultry market in Shanghai, China. Using PCR and sequencing analysis, we obtained the complete genome sequences of the DK28 virus. The sequence analysis demonstrated that this H4N2 virus was a novel multiple-gene reassortant avian influenza virus (AIV) whose genes originated from H1N1, H1N3, H3N3, H4N2, and H4N6. Knowledge regarding the complete genome sequences of the DK28 virus will be useful for epidemiological surveillance.