Highly selective c-Jun N-terminal kinase (JNK) 2 and 3 inhibitors with in vitro CNS-like pharmacokinetic properties prevent neurodegeneration

In this Letter, we describe the discovery of selective JNK2 and JNK3 inhibitors, such as 10, that routinely exhibit >10-fold selectivity over JNK1 and >1000-fold selectivity over related MAPKs, p38α and ERK2. Substitution of the naphthalene ring affords an isoform selective JNK3 inhibitor, 30, with approximately 10-fold selectivity over both JNK1 and JNK2. A naphthalene ring penetrates deep into the selectivity pocket accounting for the differentiation amongst the kinases. Interestingly, the gatekeeper Met146 sulfide interacts with the naphthalene ring in a sulfur-π stacking interaction. Compound 38 ameliorates neurotoxicity induced by amyloid-β in human cortical neurons. Lastly, we demonstrate how to install propitious in vitro CNS-like properties into these selective inhibitors.     

Amino-caprolactam γ-secretase inhibitors showing potential for the treatment of Alzheimer's disease

Herein we describe the structure-activity relationship (SAR) of amino-caprolactam analogs derived from amino-caprolactam benzene sulfonamide 1, highlighting affects on the potency of γ-secretase inhibition, selectivity for the inhibition of APP versus Notch processing by γ-secretase and selected pharmakokinetic properties. Amino-caprolactams that are efficacious in reducing the cortical Aβ_x-40 levels in FVB mice via a single 100 mpk IP dose are highlighted.     

NMR determination of pKa values in α-synuclein

The intrinsically unfolded protein α-synuclein has an N-terminal domain with seven imperfect KTKEGV sequence repeats and a C-terminal domain with a large proportion of acidic residues. We characterized pK(a) values for all 26 sites in the protein that ionize below pH 7 using 2D (1) H-(15) N HSQC and 3D C(CO)NH NMR experiments. The N-terminal domain shows systematically lowered pK(a) values, suggesting weak electrostatic interactions between acidic and basic residues in the KTKEGV repeats. By contrast, the C-terminal domain shows elevated pK(a) values due to electrostatic repulsion between like charges. The effects are smaller but persist at physiological salt concentrations. For α-synuclein in the membrane-like environment of sodium dodecylsulfate (SDS) micelles, we characterized the pK(a) of His50, a residue of particular interest since it is flanked within one turn of the α-helix structure by the Parkinson's disease-linked mutants E46K and A53T. The pK(a) of His50 is raised by 1.4 pH units in the micelle-bound state. Titrations of His50 in the micelle-bound states of the E46K and A53T mutants show that the pK(a) shift is primarily due to interactions between the histidine and the sulfate groups of SDS, with electrostatic interactions between His50 and Glu46 playing a much smaller role. Our results indicate that the pK(a) values of uncomplexed α-synuclein differ significantly from random coil model peptides even though the protein is intrinsically unfolded. Due to the long-range nature of electrostatic interactions, charged residues in the α-synuclein sequence may help nucleate the folding of the protein into an α-helical structure and confer protection from misfolding.     

Participation of the liver gluconeogenesis in the glibenclamide-induced hypoglycaemia in rats

We previously demonstrated an increased liver gluconeogenesis (LG) during insulin‐induced hypoglycaemia. Thus, an expected effect of sulphonylureas induced hypoglycaemia (SIH) could be the activation of LG. However, sulphonylureas infused directly in to the liver inhibits LG. Considering these opposite effects we investigated herein LG in rats submitted to SIH. For this purpose, 24 h fasted rats that received glibenclamide (10 mg kg^?1) were used (SIH group). Control group received oral saline. Glycaemia at 30, 60, 90, 120 and 150 min after oral administration of glibenclamide were evaluated. Since the lowest glycaemia was obtained 120 min after glibenclamide administration, this time was chosen to investigate LG in situ perfused livers. The gluconeogenesis from precursors that enters in this metabolic pathway before the mitochondrial step, i.e. L ‐alanine (5 mM), L ‐lactate (2 mM), pyruvate (5 mM) and L ‐glutamine were decreased (p < 0·05). However, the gluconeogenic activity using glycerol (2 mM), which enters in the gluconeogenesis after the mitochondrial step was maintained. Taken together, the results suggest that the inhibition of LG promoted by SIH overcome the activation of this metabolic pathway promoted by IIH and could be attributed, at least in part, to its effect on mitochondrial function. Copyright © 2011 John Wiley & Sons, Ltd.     

Structure and gene cluster of the O-antigen of Escherichia coli O109; chemical and genetic evidences of the presence of L-RhaN3N derivatives in the O-antigens of E. coli O109 and O119

O-antigen representing the O-polysaccharide chain of the lipopolysaccharide is the most variable constituent on the cell surface of Gram-negative bacteria and a player in their pathogenicity. The O-polysaccharide of Escherichia coli O109 was studied by sugar analysis and nuclear magnetic resonance spectroscopy and found to contain a rarely occurring monosaccharide, 2,3-diacetamido-2,3,6-trideoxy-l-mannose (l-RhaNAc3NAc). The following structure of the tetrasaccharide repeating unit of the O-polysaccharide was established, which is closely related to that of Proteus penneri O66: Ac--4-β-L-RhapNAc3NAc -->4)-α-D-Glcp-(1-->3)-α-L-6dTalp-(1-->3)-β-D-GlcpNAc-(1-->. The O-antigen gene cluster of E. coli O109 was sequenced and all 14 genes found were assigned functions based on their similarity to genes from the available databases. Putative genes for synthesis of l-RhaN3N were found in E. coli O109 and their homologues in E. coli O119, whose O-antigen has been reported earlier to contain 2-acetamido-2,3,6-trideoxy-3-formamido-d-mannose (d-RhaNAc3NFo). Analysis by GLC of the (S)-2-octyl glycosides confirmed that the absolute configuration of RhaN3N in E. coli O119 should be revised from D TO L.     

Multiple potential targets of opioids in the treatment of acute respiratory distress syndrome from COVID-19

COVID-19 can present with a variety of clinical features, ranging from asymptomatic or mild respiratory symptoms to fulminant acute respiratory distress syndrome (ARDS) depending on the host's immune responses and the extent of the associated pathologies. This implies that several measures need to be taken to limit severely impairing symptoms caused by viral-induced pathology in vital organs. Opioids are most exploited for their analgesic effects but their usage in the palliation of dyspnoea, immunomodulation and lysosomotropism may represent potential usages of opioids in COVID-19. Here, we describe the mechanisms involved in each of these potential usages, highlighting the benefits of using opioids in the treatment of ARDS from SARS-CoV-2 infection.     

Flotillin-1 stabilizes caveolin-1 in intestinal epithelial cells

Flotillins and caveolins represent two types of resident proteins associated with lipid rafts in mammalian cells, however, their possible cross-talk in regulating lipid raft functions remains poorly understood. In this report, we observed that siRNA-mediated down-regulation of flotillin-1 expression which disrupted lipid raft-mediated endocytosis of BODIPY FL C₅-lactosylceramide also substantially decreased caveolin-1 level in SK-CO15 human intestinal epithelial cells. The decrease in caveolin-1 expression appeared to be specific for flotillin-1 knock-down and was not observed after down-regulation of flotillin-2. The decrease in caveolin-1 level in flotillin-1-depleted cells was not due to suppression of its mRNA synthesis and was not mimicked by cholesterol depletion of SK-CO15 cells. Furthermore, flotillin-1 dependent down-regulation of caveolin-1 was reversed after cell exposure to lysosomal inhibitor, chloroquine but not proteosomal inhibitor, MG262. Our data suggest that flotillin-1 regulates caveolin-1 level by preventing its lysosomal degradation in intestinal epithelial cells.     

A polycystin‐2 (TRPP2) dimerization domain essential for the function of heteromeric polycystin complexes

Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in two genes, PKD1 and PKD2, which encode polycystin‐1 (PC1) and polycystin‐2 (PC2), respectively. Earlier work has shown that PC1 and PC2 assemble into a polycystin complex implicated in kidney morphogenesis. PC2 also assembles into homomers of uncertain functional significance. However, little is known about the molecular mechanisms that direct polycystin complex assembly and specify its functions. We have identified a coiled coil in the C‐terminus of PC2 that functions as a homodimerization domain essential for PC1 binding but not for its self‐oligomerization. Dimerization‐defective PC2 mutants were unable to reconstitute PC1/PC2 complexes either at the plasma membrane (PM) or at PM‐endoplasmic reticulum (ER) junctions but could still function as ER Ca²⁺‐release channels. Expression of dimerization‐defective PC2 mutants in zebrafish resulted in a cystic phenotype but had lesser effects on organ laterality. We conclude that C‐terminal dimerization of PC2 specifies the formation of polycystin complexes but not formation of ER‐localized PC2 channels. Mutations that affect PC2 C‐terminal homo‐ and heteromerization are the likely molecular basis of cyst formation in ADPKD.     

Plasmonic Enhancement of Dye Sensitized Solar Cells via a Tailored Size-Distribution of Chemically Functionalized Gold Nanoparticles

A substantial and stable increase of the current density J_sc of ruthenium (Ru) dye sensitized solar cells (DSC) of up to 16.18% and of the power efficiency of up to 25.5% is demonstrated in this article via plasmonic enhancement. The key aspect of this work is the use of a tailored bimodal size distribution of functionalized gold nanoparticles (AuNPs) that have been chemically immobilized onto the mesoporous titanium dioxide (TiO₂) layer via short, stable dithiodibutyric acid linkers. The size distribution of the AuNPs is a result of theoretical calculations that aimed at the perfection of the absorption characteristics of the complete solar cell system over a wide range of wavelengths. The functionalization of the AuNPs serves to bind them at a close but defined distance to TiO₂-particles and additionally to chemically protect them against potential corrosion by the electrolyte. Simulations of near field (enhanced absorption) and far field (scattering) contributions have been used to tailor a complex AuNPs bimodal size distribution that had subsequently demonstrated experimentally a close to optimum improvement of the absorbance over a wide wavelength range (500–675 nm) and therefore an impressive DSC efficiency enhancement. Finally, the modified DSCs are exhibiting pronounced longevity and stable performance as confirmed via long time measurements. In summary, the presented systems show increased performance compared to non plasmonic enhanced cells with otherwise identical composition, and are demonstrating a previously unpublished longevity for iodide electrolyte/AuNPs combinations.