Hideki Azuma

The conjugation of diphtheria toxin T domain to poly(ethylenimine) based vectors for enhanced endosomal escape during gene transfection

The endosomal escape is a well-known serious obstacle for non-viral gene delivery. This is because of an acidic and enzymatic degradation of the contents of the endosome/lysosome. Therefore, the internalized gene needs to be efficient released into the cytosol to obtain the efficiently transfection efficiency. On the other hand, the diphtheria toxin T domain fuses with endosome membrane by pH decrease, then enhances the endosomal escape of the diphtheria toxin C fragment. In this study, we constructed diphtheria toxin T domain-conjugated poly(ethylenimine)s (PEI) polyplex for enhancing the endosomal escape of exogenous gene. The conjugation of diphtheria toxin T domain with PEI/pDNA polyplex leads to the significant enhancement of transfection efficiency when compared with plain PEI/pDNA polyplex. The pH-responsive increase in hydrophobicity of the diphtheria toxin T domain might not only trigger the perturbation of the endocytic vesicle membrane but might also increase the membrane permeability.

Apoptotic activities of C2-ceramide and C2-dihydroceramide homologues against HL-60 cells

The apoptotic activities of non-natural ceramide homologues, C2-homo-ceramide, C2-homo-dihydroceramide, C2-bishomo-ceramide and C2-bishomo-dihydroceramide, were examined using human leukemia HL-60 cells. The apoptotic activity was in order of C2-ceramide>C2-homo-ceramide approximately C2-bishomo-ceramide and the activities of the L-erythro- and D-erythro-ceramide homologues were similar. The morphological features of the cells, DNA fragmentations, proteolytic processing of pro-caspase-3 and the cleavage of PARP as the result of treatments with these homologues indicated that cell death was induced by apoptosis.

S-Allyl cysteine improves nonalcoholic fatty liver disease in type 2 diabetes Otsuka Long-Evans Tokushima Fatty rats via regulation of hepatic lipogenesis and glucose metabolism

It is important to prevent and improve diabetes mellitus and its complications in a safe and low-cost manner. S-Allyl cysteine, an aged garlic extract with antioxidant activity, was investigated to determine whether S-allyl cysteine can improve type 2 diabetes in Otsuka Long-Evans Tokushima Fatty rats with nonalcoholic fatty liver disease. Male Otsuka Long-Evans Tokushima Fatty rats and age-matched Long-Evans Tokushima Otsuka rats were used and were divided into two groups at 29 weeks of age. S-Allyl cysteine (0.45% diet) was administered to rats for 13 weeks. Rats were killed at 43 weeks of age, and detailed analyses were performed. S-Allyl cysteine improved hemoglobinA1c, blood glucose, triglyceride, and low-density lipoprotein cholesterol levels. Furthermore, S-allyl cysteine normalized plasma insulin levels. S-Allyl cysteine activated the mRNA and protein expression of both peroxisome proliferator-activated receptor α and γ, as well as inhibiting pyruvate dehydrogenase kinase 4 in Otsuka Long-Evans Tokushima Fatty rat liver. Sterol regulatory element-binding protein 1c and forkhead box O1 proteins were normalized by S-allyl cysteine in Otsuka Long-Evans Tokushima Fatty rat liver. In conclusions, these findings support the hypothesis that S-allyl cysteine has diabetic and nonalcoholic fatty liver disease therapeutic potential as a potent regulating agent against lipogenesis and glucose metabolism.

Synthesis of novel and non-natural ceramide analogues derived from L-glutamic acid

Abstract Novel and non-natural ceramide analogues, having a different methylene spacer between the primary hydroxymethyl group and aminomethane of sphingosine backbone, have been prepared from l -glutamic acid. The key step in the preparation is the diastereoselective reduction of an enone adjacent to a Boc protected amino group by reducing agents.

Synthesis of non-natural C2-homo-ceramide and its apoptotic activity against HL-60 cells.

Non-natural ceramide analogues, C2-homo-ceramide and C2-homo-dihydroceramide, were prepared from L-aspartic acid via L-homo-serine. The apoptotic activities of the synthesized ceramide analogues were examined in HL-60 human leukemia cells. C2-homo- and C2-bishomo-ceramide indicate low but considerable apoptotic activities in comparison with C2-ceramide.

Therapeutic administration of an ingredient of aged-garlic extracts, S-allyl cysteine resolves liver fibrosis established by carbon tetrachloride in rats.

S-allyl cysteine (SAC) is the most abundant compound in aged garlic extracts (AGEs). AGE has been reported to ameliorate the oxidative damage implicated in a variety of diseases. However, the effects of SAC have not been established in liver cirrhosis. The aim of this study was to examine the effect of therapeutic administration of SAC in liver cirrhosis by chronic carbon tetrachloride (CCl4) administration in rats. SAC or other cysteine compounds were administered from 4 weeks when liver fibrosis was confirmed to be in process. CCl4 administration elevated plasma alanine aminotransferase, plasma lipid peroxidation, liver hydroxyproline, and liver transforming growth factor (TGF)-β at 12 weeks. SAC prevented these changes induced by CCl4. Furthermore, SAC improved survival in a dose-dependent manner following consecutive CCl4 administration. The inhibitory mechanisms may be associated with a decrease in the profibrogenic cytokine, TGF-β as well as the antioxidative properties of SAC.

Protein recognition of hetero-/homoleptic ruthenium(II) tris(bipyridine)s for α-chymotrypsin and cytochrome c.

We examined the relationship between the structures of hetero-/homoleptic ruthenium(II) tris(bipyridine) metal complexes (Ru(II)(bpy)(3)) and their binding properties for α-chymotrypsin (ChT) and cytochrome c (cyt c). Heteroleptic compound 1a binds to both ChT and cyt c in 1:1 ratio, whereas homoleptic 2 forms 1:2 protein complex with ChT but 1:1 complex with cyt c. These results suggest that the structure of the recognition cavity in Ru(II)(bpy)(3) can be designed for shape complementarity to the targeted proteins. In addition, Ru(II)(bpy)(3) complexes were found to be potent inhibitors of cyt c reduction and to permeate A549 cells.

Enhanced internalization and endosomal escape of dual-functionalized poly(ethyleneimine)s polyplex with diphtheria toxin T and R domains.

A new multifunctional gene delivery system was constructed with diphtheria toxins functional domains. Used functional domains are T domain for endosomal escape and R domain for efficient internalization into cell. In order to conjugate these domains into PEI polyplex, diphtheria toxin T and R domains-streptavidin fusion protein (DTRS) was prepared. The conjugation of the DTRS with biotinylated PEI polyplex (DTRS-polyplex) lead to the significant enhancement of transfection efficiency when compared with plain PEI/pDNA polyplex in CHO-K1 cell. It was demonstrated that DTRS-polyplex had high endosomal escape efficiency and internalization efficiency by several measurements, such as in vitro intracellular trafficking observation and the internalization inhibition with several inhibitors. These results suggest that this multifunctional non-viral vector may contribute to the future cancer gene therapy.

HVJ-E/importin-β hybrid vector for overcoming cytoplasmic and nuclear membranes as double barrier for non-viral gene delivery

In order to enhance the nuclear import of the transgene, we prepared plasmid DNA/importin-β conjugates consisting of biotinylated poly(ethylenimine)s and recombinant streptavidin-fused importin-β. Hemagglutinating virus of Japan-envelope vector containing the PEI polyplex/importin-β conjugate showed high transfection efficiency not only in vitro but also in vivo. We showed that novel HVJ-E/importin-β-conjugated PEI polyplex hybrid vector could overcome plasma and nuclear membrane barriers to achieve effective transfection.

cis-Diamines as active catalysts for the decarboxylation of oxalacetate

3-endo-Dimethylaminomethyl-1,7,7-trimethylnorbornan-2-endo-amine (cis-1) and 3-endo-dimethylaminomethyl-1,7,7-trimethylnorbornan-2-exo-amine (trans-1), and the related acyclic 1,3-diamines have been examined for their catalytic activities in the decarboxylation of oxalacetate. The most active catalyst was found to be cis-1 involving the Schiff base intermediate. Available evidence indicated that a neighbouring cis configuration of two amino groups has dual functions: (1) the activation of the primary amino group by lowering the pKa for the formation of the Schiff base intermediate at neutral pH, and (2) the stabilization of the Schiff base intermediate by electrostatic and/or hydrogen bonding.