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The influenza A virus (IAV) consists of 8 single-stranded, negative-sense viral RNA (vRNA) segments. After infection, vRNA is transcribed, replicated, and wrapped by viral nucleoprotein (NP) to form viral ribonucleoprotein (vRNP). The transcription, replication, and nuclear export of the viral genome are regulated by the IAV protein, NS2, which is translated from spliced mRNA transcribed from viral NS vRNA. This splicing is inefficient, explaining why NS2 is present in low abundance after IAV infection. The levels of NS2 and its subsequent accumulation are thought to influence viral RNA replication and vRNP nuclear export. Here we show that NS2 is ubiquitinated at the K64 and K88 residues by K48-linked and K63-linked polyubiquitin (polyUb) chains, leading to the degradation of NS2 by the proteasome. Additionally, we show that a host deubiquitinase, OTUB1, can remove polyUb chains conjugated to NS2, thereby stabilizing NS2. Accordingly, knock down of OTUB1 by siRNA reduces the nuclear export of vRNP, and reduces the overall production of IAV. These results collectively demonstrate that the levels of NS2 in IAV-infected cells are regulated by a ubiquitination-deubiquitination system involving OTUB1 that is necessary for optimal IAV replication. Author summary: The influenza A virus (IAV) protein, NS2, plays a critical role in virus replication, as the abundance of NS2 influences viral transcription, viral RNA (vRNA) synthesis, and viral ribonucleoprotein (vRNP) export from the nucleus. Interestingly, high levels of NS2 are known to inhibit IAV transcription yet promote vRNA synthesis. In this study, we found that ubiquitination destabilizes NS2, and a host deubiquitinase, OTUB1, was shown to deubiquitinate and stabilize NS2, thus contributing to NS2 accumulation. OTUB1 has previously been reported to be a negative regulator of host cellular antiviral defense, and its upregulation enhances virion production. Our study sheds additional light on the role of OTUB1 during IAV infection which can now be considered for the development of anti-influenza strategies. [ABSTRACT FROM AUTHOR]

A 37-kb DNA fragment, which has five fengyin synthetase genes, including fenC, fenD, fenE, fenA and fenB, was cloned and sequenced. Among these genes, fenC encodes a fengyin synthetase 2,560-amino acids long with an estimated molecular mass of 287 kDa. This protein has two amino acid activation modules, FenC1 and FenC2, which activate L-glutamic acid and L-ornithine, respectively. Primer extension, employing mRNA isolated from the log-phase cells, identified a transcription start site found 86 nucleotides upstream from the initiation codon of fenC.

In this study, a marine medicinal brown alga Sargassum cristaefolium-derived fungal strain Xylaria acuta SC1019 was isolated and identified. Column chromatography of the extracts from liquid- and solid-fermented products of the fungal strain was carried out, and led to the isolation of twenty-one compounds. Their structures were characterized by spectroscopic analysis, and the absolute configurations were further established by single X-ray diffraction analysis or modified Mosher's method as nine previously undescribed compounds, namely xylarilactones A-C (1-3), ent-gedebic acid 8-O-α-D-glucopyranoside (4), 5R-hydroxylmethylmellein 11-O-α-D-glucopyranoside (5), ent-hymatoxin E 16-O-α-D-mannopyranoside (6), 19,20-epoxycytochalasin S (7), 19,20-epoxycytochalasin T (8), and (2R)-butylitaconic acid (9), along with twelve known compounds 10-21. All the isolates were subjected to anti-inflammatory and anti-angiogenic assays. Compounds 1, 5, 7, 10, and 17 showed moderate nitric oxide production inhibitory activities in lipopolysaccharide-activated BV-2 microglial cells with IC 50 values of 19.55 ± 0.35, 16.10 ± 0.57, 15.20 ± 0.87, 11.76 ± 0.49, and 11.30 ± 0.32 μM, respectively, as compared to curcumin (IC 50 = 2.69 ± 0.34 μM) without any significant cytotoxicity. Compounds 7, 8, and 21 displayed potent anti-angiogenic activities by suppressing the growth of human endothelial progenitor cells with IC 50 values of 0.44 ± 0.01, 0.47 ± 0.03, and 0.53 ± 0.01 μM, respectively, as compared to sorafenib (IC 50 = 5.50 ± 1.50 μM).

Zta, encoded by the BZLF1 gene of Epstein-Barr virus (EBV), is a transcription factor that is expressed during the immediate-early stage of the lytic cycle. The expression of Zta is crucial to viral lytic development. Earlier studies showed that Ku80 is a binding partner of Zta in ZKO-293 cells and is co-purified with Zta. This study verifies the interaction between Ku80 and Zta by using glutathione S-transferase-pull-down and co-immunoprecipitation assays, and also by indirect immunofluorescence analysis. This investigation also reveals that Ku80 binds to Zta on Zta-response elements in the BHLF1 promoter, enhancing the promoter activity. This study also reveals that the interaction between Zta and Ku80 involves the C-terminal region of Zta and the 425 aa N-terminal region of Ku80. The interaction between these two proteins and the enhancement of transcription that is activated by Zta suggest that Ku80 is important to EBV lytic development.

The hedgehog (Hh) transcription factor Gli induces transformation of epithelial cells via induction of Snail, a repressor of E-cadherin. Epithelial-mesenchymal transition is also a determinant of the progression of tumorigenesis, following down-regulation of E-cadherin. However, the role of Hh signaling components and Snail/E-cadherin in brain tumors is not yet fully understood. We analyzed the expression of Hh signaling components and Snail/E-cadherin in 69 brain tumors by reverse transcription-polymerase chain reaction (RT-PCR). The data showed that overexpression of Smo (35/69), Ptch (50/69), Gli1 (56/69), Gli2 (29/69) and N-myc (39/69) might contribute to brain tumorigenesis. Our results also indicated that Snail and E-cadherin showed opposing expression in malignant tumors (high grade astrocytoma and metastasis). Snail and E-cadherin showed less correlation in benign brain tumors. We further investigated mutations of Gli2 and Snail by RT-PCR and direct sequencing. No mutation was observed on Gli2 but several sporadic mutations on Snail were found, including S96G, S111L, S111L/S119Y and one nonsense mutation at codon 158 (Y158*). An in vitro E-cadherin promoter assay showed that S96G, S111L, S111L/S119Y Snail mutants were decreased by 15, 25 and 50%, respectively, whereas Y158* was increased by 40% compared to wild-type. Furthermore, our data showed that wild-type Snail and S96G, S111L, S111L/S119Y translocated to the nucleus, while the Y158* mutant failed to translocate to the nucleus. Taken together, our results demonstrate that Hh signaling components, the expression and mutations of Snail and the expression of E-cadherin may play an important role in human brain tumorigenesis.

Aurora-A is involved in chromosome alignment, centrosome maturation, mitotic spindle assembly and regards to an oncogene. Aurora-A is also known to bind to several other proteins affecting its up-regulation or down-regulation and localization. However, how these different binding signals work together to regulate Aurora-A is not properly known. To explore more Aurora-A interacting proteins, the low-copy yeast two-hybrid screening using Aurora-A as bait protein was performed. One novel gene, AIBp, was demonstrated to associate with Aurora-A by the yeast two-hybrid method and in vitro GST pull-down assay. Molecular characterization showed that AIBp possessed a binding site at the C-terminal with Aurora-A (kinase domain). Interestingly, AIBp also interacts with hNinein at the N-terminal, which overlaps with a previously reported hNinein and GSK3beta binding site. Using a kinase assay, AIBp interacts with the Aurora-A kinase domain functions as a positive regulator, whereas AIBp binding to hNinein appears to block the phosphorylation of hNinein by both Aurora-A and GSK3beta. siRNA-mediated elimination of AIBp from HeLa cells, results in a doughnut-like shape, asymmetrical spindle pole and multiple spindle pole formation. We also demonstrated that both AIBp and Aurora-A are co-overexpressed in various brain tumors. These studies demonstrate that AIBp may not only be required for the dynamic movement of Aurora-A at the centrosomes and spindle apparatus during the cell cycle, but may also be important during brain tumorigenesis.