Potent and selective inhibition of angiotensin AT1 receptor signaling by RGS2: roles of its N-terminal domain

Emerging evidence indicates that R4/B subfamily RGS (regulator of G protein signaling) proteins play roles in functional regulation in the cardiovascular system. In this study, we compared effects of three R4/B subfamily proteins, RGS2, RGS4 and RGS5 on angiotensin AT1 receptor signaling, and investigated roles of the N-terminus of RGS2. In HEK293T cells expressing AT1 receptor stably, intracellular Ca²⁺ responses induced by angiotensin II were much more strongly attenuated by RGS2 than by RGS4 and RGS5. N-terminally deleted RGS2 proteins lost this potent inhibitory effect. Replacement of the N-terminal residues 1-71 of RGS2 with the corresponding residues (1-51) of RGS5 decreased significantly the inhibitory effect. On the other hand, replacement of the residues 1-51 of RGS5 with the residues 1-71 of RGS2 increased the inhibitory effect dramatically. Furthermore, we investigated functional contribution of N-terminal subdomains of RGS2, namely, an N-terminal region (residues 16-55) with an amphipathic α helix domain (the subdomain N1), a probable non-specific membrane-targeting subdomain, and another region (residues 56-71) between the α helix and the RGS box (the subdomain N2), a probable GPCR-recognizing subdomain. RGS2 chimera proteins with the residues 1-33 or 34-52 of RGS5 showed weak inhibitory activity, and either of RGS5 chimera proteins with residues 1-55 or 56-71 of RGS2 showed strong inhibitory effects on AT1 receptor signaling. The present study indicates the essential roles of both N-terminal subdomains for the potent inhibitory activity of RGS2 on AT1 receptor signaling.     

Characterisation of source-separated household waste intended for composting

Large-scale composting of source-separated household waste has expanded in recent years in the Nordic countries. One problem can be low pH at the start of the process. Incoming biowaste at four composting plants was characterised chemically, physically and microbiologically. The pH of food waste ranged from 4.7 to 6.1 and organic acid concentration from 24 to 81 mmol kg(-1). The bacterial diversity in the waste samples was high, with all samples dominated by Gammaproteobacteria, particularly Pseudomonas and Enterobacteria (Escherichia coli, Klebsiella, Enterobacter). Lactic acid bacteria were also numerically important and are known to negatively affect the composting process because the lactic acid they produce lowers the pH, inhibiting other bacteria. The bacterial groups needed for efficient composting, i.e. Bacillales and Actinobacteria, were present in appreciable amounts. The results indicated that start-up problems in the composting process can be prevented by recycling bulk material and compost.     

Plasma free amino acid kinetics in rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>) using a bolus injection of <Superscript>15</Superscript>N-labeled amino acids

To gain insight into the metabolic design of the amino acid carrier systems in fish, we injected a bolus of ¹⁵N amino acids into the dorsal aorta in mature rainbow trout (Oncorhynchus mykiss). The plasma kinetic parameters including concentration, pool size, rate of disappearance (R _d), half-life and turnover rate were determined for 15 amino acids. When corrected for metabolic rate, the R _d values obtained for trout for most amino acids were largely comparable to human values, with the exception of glutamine (which was lower) and threonine (which was higher). R _d values ranged from 0.9 μmol 100 g⁻¹ h⁻¹ (lysine) to 22.1 μmol 100 g⁻¹ h⁻¹ (threonine) with most values falling between 2 and 6 μmol 100 g⁻¹ h⁻¹. There was a significant correlation between R _d and the molar proportion of amino acids in rainbow trout whole body protein hydrolysate. Other kinetic parameters did not correlate significantly with whole body amino acid composition. This indicates that an important design feature of the plasma-free amino acids system involves proportional delivery of amino acids to tissues for protein synthesis.     

Renin inhibitors for the treatment of hypertension: design and optimization of a novel series of tertiary alcohol-bearing piperidines

The design and optimization of a novel series of renin inhibitor is described herein. Strategically, by committing the necessary resources to the development of synthetic sequences and scaffolds that were most amenable for late stage structural diversification, even as the focus of the SAR campaign moved from one end of the molecule to another, highly potent renin inhibitors could be rapidly identified and profiled.     

Renin inhibitors for the treatment of hypertension: design and optimization of a novel series of spirocyclic piperidines

The discovery and SAR of a novel series of spirocyclic renin inhibitors are described herein. It was found that by restricting the northern aromatic plate to the bioactive conformation through spirocyclization, increase in renin potency and decrease in hERG affinity could both be realized. When early members of this series were found to be potent time-dependent CYP3A4 inhibitors, two distinct strategies to address this liability were explored and this effort culminated in the identification of compound 31 as an optimized renin inhibitor.     

Structure-based parallel medicinal chemistry approach to improve metabolic stability of benzopyran COX-2 inhibitors

Combination of the structure-based design and solid-phase parallel synthesis provided an integrated approach to rapidly develop the structure-activity relationship of benzopyran COX-2 inhibitors. Binding free energies predicted by free energy perturbation theory yielded good agreement with experimental results. New potent and selective lead compounds with improved metabolic properties were identified.     

Divergent strategies for controlling the nuclear membrane satisfy geometric constraints during nuclear division

Eukaryotes segregate chromosomes in "open" or "closed" mitosis, depending on whether their nuclear envelopes (NEs) break down or remain intact. Here we show that the control of the nuclear surface area may determine the choice between these two modes. The dividing nucleus does not expand its surface in the fission yeast Schizosaccharomyces japonicus, confining the mitotic spindle and causing it to?buckle. The NE ruptures in anaphase, releasing the compressive stress and allowing chromosome segregation.?Blocking the NE expansion in the related species Schizosaccharomyces pombe that undergoes closed mitosis induces spindle buckling and collapse in the absence of an intrinsic NE rupture mechanism. We propose that scaling considerations could have shaped the evolution of eukaryotic mitosis by necessitating either nuclear surface expansion or the NE breakdown.     

Synthesis and in vitro anti-hepatitis B virus activity of six-membered azanucleoside analogues

Fifteen novel six-membered azanucleoside derivatives were prepared and evaluated for their anti-hepatitis B virus (HBV) activity and cytotoxicity in human hepatoblastoma-derived liver Hep-G2 cells. The most potent compound 16b with an IC(50) value of 2.74μg/mL (lower than 3TC) and a SI value of 13.5 was disclosed. The key synthetic steps involved the rearrangement of lactones (which were readily obtained from monosaccharides) and the Lewis acid-catalyzed condensation of nucleobases with azasugar donors. Using the versatile acetylated azasugar donors, azanucleosides covering three types of azasugars and four types of natural nucleobases were successfully obtained. The experimental results showed that some six-membered azanucleosides may find applications in the discovery of new anti-viral agents.