Identification of 2,3-disubstituted pyridines as potent,orally active PDE4 inhibitors

A series of 2,3-disubstituted pyridines were synthesized and evaluated for their PDE4 inhibitory activity. We successfully modified undesirable cyano group of initial lead compound 2 to 4-pyridyl group with improvement of in vitro efficacy and optimized the position of nitrogen atoms in pyridine moiety and alkylene linker. The most potent compound showed significant efficacy in animal models of asthma and inflammation.     

Correlation Analysis between Eating Quality,Rheological Property and Amylose Content of Starch

A screening was designed to isolate microorganisms having poly(γ-glutamic acid) (PGA) endohydrolase activity. Of the strains screened, TM-4222, from a soil sample, showed the highest viscosity decrement ability on PGA. It was identified to be a Myrothecium sp. The fungal production of the enzyme was slightly promoted with yeast extract and greatly promoted with· both yeast extract and PGA. The fungus was evaluated to produce PGA hydrolase of an endo-type specificity by analyzing of the reaction products.     

A Combination of Mitochondrial Oxidative Stress and Excess Fat/Calorie Intake Accelerates Steatohepatitis by Enhancing Hepatic CC Chemokine Production in Mice

Mitochondrial oxidative stress is considered as a key accelerator of fibrosis in various organs including the liver. However, the production of oxidative stress and progression of liver fibrosis may merely represent the independent consequences of hepatocellular injury caused by the primary disease. Because of a lack of appropriate experimental models to evaluate the sole effects of oxidative stress, it is virtually unknown whether this stress is causatively linked to the progression of liver fibrosis. Here, we examined the direct effects of mitochondrial reactive oxygen species (ROS) on the progression of high fat/calorie diet-induced steatohepatitis using Tet-mev-1 mice, in which a mutated succinate dehydrogenase transgene impairs the mitochondrial electron transport and generates an excess amount of ROS in response to doxycycline administration. Wild type and Tet-mev-1 mice that had been continuously given doxycycline-containing water were subsequently fed either normal chow or a cholesterol-free high-fat/high-sucrose diet for 4 months at approximately 1 or 2 years of age. Histopathological examinations indicated that neither the mitochondrial ROS induced in Tet-mev-1 mice nor the feeding of wild type animals with high-fat/high-sucrose diet alone caused significant liver fibrosis. Only when the Tet-mev-1 mice were fed a high-fat/high-sucrose diet, it induced lipid peroxidation in hepatocytes and enhanced hepatic CC chemokine expression. These events were accompanied by increased infiltration of CCR5-positive cells and activation of myofibroblasts, resulting in extensive liver fibrosis. Interestingly, this combinatorial effect of mitochondrial ROS and excess fat/calorie intake on liver fibrosis was observed only in 2-year-old Tet-mev-1 mice, not in the 1-year-old animals. Collectively, these results indicate that mitochondrial ROS in combination with excess fat/calorie intake accelerates liver fibrosis by enhancing CC chemokine production in aged animals. We have provided a good experimental model to explore how high fat/calorie intake increases the susceptibility to nonalcoholic steatohepatitis in aged individuals who have impaired mitochondrial adaptation.     

Inhibition of lipases by epsilon-polylysine

Oral administration of epsilon-polylysine to rats reduced the peak plasma triacylglycerol concentration. In vitro, epsilon-polylysine and polylysine strongly inhibited the hydrolysis, by either pancreatic lipase or carboxylester lipase, of trioleoylglycerol (TO) emulsified with phosphatidylcholine (PC) and taurocholate. The epsilon-polylysine concentration required for complete inhibition of pancreatic lipase, 10 microg/ml, is 1,000 times lower than that of BSA required for the same effect. Inhibition requires the presence of bile salt and, unlike inhibition of lipase by other proteins, is not reversed by supramicellar concentrations of bile salt. Inhibition increases with the degree of polylysine polymerization, is independent of lipase concentration, is independent of pH between 5.0 and 9.5, and is accompanied by an inhibition of lipase binding to TO-PC emulsion particles. However, epsilon-polylysine did not inhibit the hydrolysis by pancreatic lipase of TO emulsions prepared using anionic surfactants, TO hydrolysis catalyzed by lingual lipase, or the hydrolysis of a water-soluble substrate. In the presence of taurocholate, epsilon-polylysine becomes surface active and adsorbs to TO-PC monomolecular films. These results are consistent with epsilon-polylysine and taurocholate forming a surface-active complex that binds to emulsion particles, thereby retarding lipase adsorption and triacylglycerol hydrolysis both in vivo and in vitro.     

Binding and dissociation of human topoisomerase I with hairpin-loop RNAs: implications for the regulation of HIV-1 replication

Cellular topoisomerase I has been reported to be present in retroviral particles and to enhance viral cDNA synthesis; however, the mechanisms involved remain unknown. In the present study, it has been demonstrated that human topoisomerase I combines with a stem-loop RNA and that the bound topoisomerase I can be dissociated from RNA substrates in the presence of ATP. In addition, in vitro cleaved synthetic RNA bound by topoisomerase I is subsequently relegated when the topoisomerase I is dissociated by ATP. A mechanism is proposed in which human topoisomerase I is carried into virions and regulates the repair of genomic RNA by its ligation activity.     

Effects of a turmeric extract (Curcuma longa) on chronic ultraviolet B irradiation-induced skin damage in melanin-possessing hairless mice

Turmeric (the rhizomes of Curcuma longa L., Zingiberacease) is widely used as a dietary pigment and spice, and has been traditionally used for the treatment of inflammation, skin wounds and hepatic disorders in Ayurvedic, Unani and Chinese medicine. Although the topical application or oral administration of turmeric is used to improve skin trouble, there is no evidence to support this effect. The aim of this study was to clarify whether turmeric prevents chronic ultraviolet B (UVB)-irradiated skin damage. We examined the effects of a turmeric extract on skin damage including changes in skin thickness and elasticity, pigmentation and wrinkling caused by long-term, low-dose ultraviolet B irradiation in melanin-possessing hairless mice. The extract (at 300 or 1000 mg/kg, twice daily) prevented an increase in skin thickness and a reduction in skin elasticity induced by chronic UVB exposure. It also prevented the formation of wrinkles and melanin (at 1000 mg/kg, twice daily) as well as increases in the diameter and length of skin blood vessels and in the expression of matrix metalloproteinase-2 (MMP-2). Prevention of UVB-induced skin aging by turmeric may be due to the inhibition of increases in MMP-2 expression caused by chronic irradiation.     

The ADP-ribosylation factor 1 gene is indispensable for mouse embryonic development after implantation

ADP-ribosylation factor (Arf) 1 is thought to affect the morphologies of organelles, such as the Golgi apparatus, and regulate protein trafficking pathways. Mice have six Arf isoforms. In knockdown experiments with HeLa cells, no single Arf isoform among Arf1–5 is required for organelle morphologies or any membrane trafficking step. This suggests that the cooperation of two or more Arfs is a general feature. Although many cell biological and biochemical analyses have proven the importance of Arf1, the physiological roles of Arf1 in mice remain unknown. To investigate the activity of Arf1 in vivo, we established Arf1-deficient mice. Arf^−/− blastocysts were identified at the expected Mendelian ratio. The appearance of these blastocysts was indistinguishable from that of wild-type and Arf^+/− blastocysts, and they grew normally in an in vitro culture system. However, Arf^−/− embryos were degenerated at E5.5, and none survived to E12.5, suggesting that they died soon after implantation. These data establish for the first time that the Arf1 gene is indispensable for mouse embryonic development after implantation.     

Crystal structure of cyclic Lys48-linked tetraubiquitin

Lys48-linked polyubiquitin chains serve as a signal for protein degradation by 26S proteasomes through its Ile44 hydrophobic patches interactions. The individual ubiquitin units of each chain are conjugated through an isopeptide bond between Lys48 and the C-terminal Gly76 of the preceding units. The conformation of Lys48-linked tetraubiquitin has been shown to change dynamically depending on solution pH. Here we enzymatically synthesized a wild-type Lys48-linked tetraubiquitin for structural study. In the synthesis, cyclic and non-cyclic species were obtained as major and minor fractions, respectively. This enabled us to solve the crystal structure of tetraubiquitin exclusively with native Lys48-linkages at 1.85 Å resolution in low pH 4.6. The crystallographic data clearly showed that the C-terminus of the first ubiquitin is conjugated to the Lys48 residue of the fourth ubiquitin. The overall structure is quite similar to the closed form of engineered tetraubiquitin at near-neutral pH 6.7, previously reported, in which the Ile44 hydrophobic patches face each other. The structure of the second and the third ubiquitin units [Ub(2)-Ub(3)] connected through a native isopeptide bond is significantly different from the conformations of the corresponding linkage of the engineered tetraubiquitins, whereas the structures of Ub(1)-Ub(2) and Ub(3)-Ub(4) isopeptide bonds are almost identical to those of the previously reported structures. From these observations, we suggest that the flexible nature of the isopeptide linkage thus observed contributes to the structural arrangements of ubiquitin chains exemplified by the pH-dependent closed-to-open conformational transition of tetraubiquitin.