Development of a novel inducer for EBV lytic therapy

Epstein-Barr virus (EBV) is a human herpesvirus that infects over 90% of the world's population that persists as a latent infection in various lymphoid and epithelial malignancies. The total number of EBV associated malignancies is estimated to exceed 200,000 new cancers per year. Current chemotherapeutic treatments of EBV-positive cancers include broad-spectrum cytotoxic drugs that ignore the EBV positive status of tumors and have limited safety and selectivity. In an effort to develop new and more efficacious molecules for inducing EBV reactivation, we have developed high-throughput screening assays to identify a class of small molecules (referred to as the C60 series) that efficiently activate the EBV lytic cycle in multiple latency types, including lymphoblastoid and nasopharyngeal carcinoma cell lines. In this paper we report our preliminary structure activity relationship studies and demonstrate reactivation of EBV in the SNU719 gastric carcinoma mouse model and the AGS-Akata gastric carcinoma mouse model.     

湛江沿海潮间带产胞外纤溶活性酶类海洋真菌的生物多样性分析

【目的】研究湛江沿海硇洲岛和徐闻珊瑚礁自然保护区潮间带产胞外纤溶酶样酶和纤溶酶原激活物海洋真菌的生物多样性,为发掘新型溶栓药物奠定基础。【方法】采用马铃薯葡萄糖琼脂(PDA)和酵母膏蛋白胨葡萄糖(YPD)培养基分离培养海洋真菌,采用真菌r DNA转录间隔区1-5.8S r DNA-转录间隔区2(ITS1-5.8S-ITS2)片段的序列分析及其系统进化树构建的方法鉴定分离培养的海洋真菌,采用脱脂牛奶马铃薯葡萄糖琼脂(SM-PDA)培养基培养法筛选产胞外蛋白酶的海洋真菌,采用海水纤维蛋白马铃薯葡萄糖琼脂(FN-PDA)培养基培养法筛选产胞外纤溶酶样酶和/或纤溶酶原激活物的海洋真菌。【结果】从湛江沿海的硇洲岛和徐闻珊瑚礁自然保护区潮间带分离、培养和鉴定了海洋真菌446株,含真菌的98个种,分布于真菌域子囊菌门(Ascomycota)和担子菌门(Basidiomycota)的6个纲、18个目、46个科、65个属;其中产胞外蛋白酶的海洋真菌有265株,61个种,分布于41个属;产胞外纤溶酶样酶的海洋真菌有67株,22个种,分布于14个属;产胞外纤溶酶原激活物的海洋真菌有84株,23种,分布于13个属;优势属为曲霉属(Aspergillus),其次为青霉属(Penicillium)。【结论】湛江沿海潮间带可分离培养的产胞外纤溶酶样酶和纤溶酶原激活物的海洋真菌物种丰富多样,是发掘新型溶栓药的丰富资源。     

Identification of a novel MTOR activator and discovery of a competing endogenous RNA regulating autophagy in vascular endothelial cells

MTOR, a central regulator of autophagy, is involved in cancer and cardiovascular and neurological diseases. Modulating the MTOR signaling balance could be of great significance for numerous diseases. No chemical activators of MTOR have been found, and the urgent challenge is to find novel MTOR downstream components. In previous studies, we found a chemical small molecule, 3-benzyl-5-((2-nitrophenoxy) methyl)–dihydrofuran-2(3H)-one (3BDO), that inhibited autophagy in human umbilical vein endothelial cells (HUVECs) and neuronal cells. Here, we found that 3BDO activated MTOR by targeting FKBP1A (FK506-binding protein 1A, 12 kDa). We next used 3BDO to detect novel factors downstream of the MTOR signaling pathway. Activation of MTOR by 3BDO increased the phosphorylation of TIA1 (TIA1 cytotoxic granule-associated RNA binding protein/T-cell-restricted intracellular antigen-1). Finally, we used gene microarray, RNA interference, RNA-ChIP assay, bioinformatics, luciferase reporter assay, and other assays and found that 3BDO greatly decreased the level of a long noncoding RNA (lncRNA) derived from the 3′ untranslated region (3′UTR) of TGFB2, known as FLJ11812. TIA1 was responsible for processing FLJ11812. Further experiments results showed that FLJ11812 could bind with MIR4459 targeting ATG13 (autophagy-related 13), and ATG13 protein level was decreased along with 3BDO-decreased FLJ11812 level. Here, we provide a new activator of MTOR, and our findings highlight the role of the lncRNA in autophagy.     

Polyamines regulate their synthesis by inducing expression and blocking degradation of ODC antizyme

Polyamines are essential organic cations with multiple cellular functions. Their synthesis is controlled by a feedback regulation whose main target is ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis. In mammals, ODC has been shown to be inhibited and targeted for ubiquitin-independent degradation by ODC antizyme (AZ). The synthesis of mammalian AZ was reported to involve a polyamine-induced ribosomal frameshifting mechanism. High levels of polyamine therefore inhibit new synthesis of polyamines by inducing ODC degradation. We identified a previously unrecognized sequence in the genome of Saccharomyces cerevisiae encoding an orthologue of mammalian AZ. We show that synthesis of yeast AZ (Oaz1) involves polyamine-regulated frameshifting as well. Degradation of yeast ODC by the proteasome depends on Oaz1. Using this novel model system for polyamine regulation, we discovered another level of its control. Oaz1 itself is subject to ubiquitin-mediated proteolysis by the proteasome. Degradation of Oaz1, however, is inhibited by polyamines. We propose a model, in which polyamines inhibit their ODC-mediated biosynthesis by two mechanisms, the control of Oaz1 synthesis and inhibition of its degradation.     

NEDD8 Ultimate Buster 1 Long (NUB1L) Protein Suppresses Atypical Neddylation and Promotes the Proteasomal Degradation of Misfolded Proteins

Neddylation is a posttranslational modification that controls diverse biological processes by covalently conjugating the ubiquitin-like protein NEDD8 to specific targets. Neddylation is commonly mediated by NEDD8-specific enzymes (typical neddylation) and, sometimes, by ubiquitin enzymes (atypical neddylation). Although typical neddylation is known to regulate protein function in many ways, the regulatory mechanisms and biological consequence of atypical neddylation remain largely unexplored. Here we report that NEDD8 conjugates were accumulated in the diseased hearts from mouse models and human patients. Proteotoxic stresses induced typical and atypical neddylation in cardiomyocytes. Loss of NUB1L exaggerated atypical neddylation, whereas NUB1L overexpression repressed atypical neddylation through promoting the degradation of NEDD8. Activation of atypical neddylation accumulated a surrogate misfolded protein, GFPu. In contrast, suppression of atypical neddylation by NUB1L overexpression enhanced GFPu degradation. Moreover, NUB1L depletion accumulated a cardiomyopathy-linked misfolded protein, CryAB^R120G, whereas NUB1L overexpression promoted its degradation through suppressing neddylation of ubiquitinated proteins in cardiomyocytes. Consequently, NUB1L protected cells from proteotoxic stress-induced cell injury. In summary, these data indicate that NUB1L suppresses atypical neddylation and promotes the degradation of misfolded proteins by the proteasome. Our findings also suggest that induction of NUB1L could potentially become a novel therapeutic strategy for diseases with increased proteotoxic stress.