イイダコ(Octopus ocellatus)卵由来の赤血球凝集素について

Hemagglutinating activity was found in extract from Octopus ocellatus eggs. The hemagglutinin was partially purified by ammonium sulfate precipitation and DEAE anion exchange chromatography. DT300, a 300 mM NaCl-eluted fraction from DEAE column, possessed Ca^-dependent hemagglutinating activity on rabbit erythrocytes at concentrations from 0.47 to 30 μg/mL. Protein bands over 200 kDa were observed in DT300 on sodium dodecyl sulfate polyacrylamide gel electrophoresis. On the other hand, ruthenium red staining gave an obvious single band on a cellulose acetate membrane. The protein and carbohydrate contents of DT300 were 24% and 2%, respectively. DT300-induced hemagglutination was inhibited by fetuin, asialofetuin, heparin, and DNA but not by heparan sulfate and mono- or oligosaccharides tested. This activity was resistant to heat and protease digestion. These results indicate that the active component having C-type lectin-like activity from octopus eggs may not be composed of protein

Viral-mediated stabilization of AU-rich element containing mRNA contributes to cell transformation

E4orf6 is one of the oncogene products of adenovirus and it also plays an important role for transportation of cellular and viral mRNA during the late phase of virus infection. We previously revealed that E4orf6 controls the fate of AU-rich element (ARE) containing mRNA by perturbing the CRM1-dependent export mechanism. Here, we show that E4orf6 stabilizes ARE-mRNA through the region required for its oncogenic activity and ubiquitin E3 ligase assembly. Cells that failed to stabilize ARE-mRNA after HuR knockdown were unable to produce colonies in soft-agar, even when E4orf6 was expressed. Furthermore, the stabilized ARE-mRNA induced the transformation of rodent immortalized cells. These findings indicate that stabilized ARE-mRNA is necessary, if not all, for the oncogenic activity of E4orf6 and has the potential to transform cells at least under a certain condition

Oncolytic potential of an E4-deficient adenovirus that can recognize the stabilization of AU-rich element containing mRNA in cancer cells

AU-rich elements (AREs) are RNA elements that enhance the rapid decay of mRNA. The fate of ARE-mRNA is controlled by ARE-binding proteins. HuR, a member of the embryonic lethal abnormal vision (ELAV) family of RNA-binding proteins, is involved in the export and stabilization of ARE-mRNA. In the vast majority of cancer cells, HuR constitutively relocates to the cytoplasm, resulting in the stabilization of ARE-mRNA. Previously, we described that the adenovirus gene product, E4orf6, which is necessary for virus replication, participates in ARE-mRNA export and stabilization. In the present study, we showed the oncolytic potential of E4orf6-deleted adenovirus dl355, which is expected to be replicated selectively in cancer cells. Virus production and cytolytic activity of dl355 were higher in cancer cells than in normal cells. HuR-depletion downregulated dl355 replication, demonstrating that ARE-mRNA stabilization is required for the production of this virus. Tumor growth was inhibited in nude mice by an intratumoral injection of dl355. Furthermore, dl355 had a stronger oncolytic effect than E1B55k-deleted adenovirus. These results indicate that dl355 has potential as an oncolytic adenovirus for a large number of cancers where ARE-mRNA is stabilized

Conditionally Replicative Adenovirus Controlled by the Stabilization System of AU-Rich Elements Containing mRNA

AU-rich elements (AREs) are RNA elements that enhance the rapid decay of mRNAs, including those of genes required for cell growth and proliferation. HuR, a member of the embryonic lethal abnormal vision (ELAV) family of RNA-binding proteins, is involved in the stabilization of ARE-mRNA. The level of HuR in the cytoplasm is up-regulated in most cancer cells, resulting in the stabilization of ARE-mRNA. We developed the adenoviruses AdARET and AdAREF, which include the ARE of TNF-alpha and c-fos genes in the 3 ' -untranslated regions of the E1A gene, respectively. The expression of the E1A protein was higher in cancer cells than in normal cells, and virus production and cytolytic activities were also higher in many types of cancer cells. The inhibition of ARE-mRNA stabilization resulted in a reduction in viral replication, demonstrating that the stabilization system was required for production of the virus. The growth of human tumors that formed in nude mice was inhibited by an intratumoral injection of AdARET and AdAREF. These results indicate that these viruses have potential as oncolytic adenoviruses in the vast majority of cancers in which ARE-mRNA is stabilized