Mutant alpha-synuclein-induced degeneration is reduced by parkin in a fly model of Parkinson's disease.

Parkinson's disease (PD) patients show a characteristic loss of motor control caused by the degeneration of dopaminergic neurons. Mutations in the genes that encode alpha-synuclein and parkin have been linked to inherited forms of this disease. The parkin protein functions as a ubiquitin ligase that targets proteins for degradation. Expression of isoforms of human alpha-synuclein in the Drosophila melanogaster nervous system forms the basis of an excellent genetic model that recapitulates phenotypic and behavioural features of PD. Using this model, we analysed the effect of parkin co-expression on the climbing ability of aging flies, their life span, and their retinal degeneration. We have determined that co-expression of parkin can suppress phenotypes caused by expression of mutant alpha-synuclein. In the developing eye, parkin reduces retinal degeneration. When co-expressed in the dopaminergic neurons, the ability to climb is extended over time. If conserved in humans, we suggest that upregulation of parkin may prove a method of suppression for PD induced by mutant forms of alpha-synuclein.     

Spontaneous cytotoxicity mediated by invertebrate mononuclear cells toward normal and malignant vertebrate targets: Inhibition by defined mono- and disaccharides

Spontaneous non-antigen-dependent cytotoxicity is displayed in vitro by mononuclear cells from molluscs, annelids, and echinoderms. The cytotoxic potential of these cells appears to be independent of prior antigenic exposure, is easily demonstrated in vitro, and is temperature dependent. The specificity of these cells may be directed at cell-surface glycoproteins on the target cell surface since a variety of defined mono- and disaccharides can block killing. The ability of sugars to block is target cell and effector cell specific. This finding is exactly analogous to our previous finding that human spontaneous monocyte-mediated cytotoxicity is blocked in a target-specific fashion by different mono- and disaccharides. These data suggest that invertebrate as well as vertebrate mononuclear cells may “recognize” targets through a series of sugar-specific “lectin-like” molecules present on the effector cell surface.     

Nucleotide pyrophosphatase of rat liver. A comparative study on the enzymes solubilized and purified from plasma membrane and endoplasmic reticulum.

Studies on the subcellular distribution of rat liver nucleotide pyrophosphatase activity revealed its presence in the plasma membrane and the endoplasmic reticulum only. The enzymes from either source were solubilized specifically with trypsin without an apparent change of their catalytic properties. A 200-fold and 1600-fold purification, respectively, was achieved by a procedure including DEAE-cellulose and affinity-chromatography with AMP as ligand, gel filtration on Sephadex G-200 and gel electrophoresis. Both nucleotide pyrophosphatases were isolated as electrophoretically homogeneous soluble proteins. They were shown to contain carbohydrate moieties. The electrophoretic mobility of both enzymes in polyacrylamide gels was identical at three pH values. Dodecylsulfate gel electrophoresis indicated a molecular weight of 137 000 for both glycoproteins. The enzymes hydrolyze a variety of purine and pyrimidine nucleotides yielding a 5'-nucleoside monophosphate. Adenosine 3':5'-monophosphate, nucleic acids and phosphate monoesters are not cleaved, but p-nitrophenyl-thymidine5'-monophosphate is readily hydrolyzed. In view of their substrate and inhibitor specificities the enzymes are considered nucleotide pyrophosphatases rather than phosphodiesterases.     

Identification and design of a novel series of MGAT2 inhibitors

[Acyl CoA]monoacylglycerol acyltransferase 2 (MGAT2) is of interest as a target for therapeutic treatment of diabetes, obesity and other diseases which together constitute the metabolic syndrome. In this Letter we report our discovery and optimisation of a novel series of MGAT2 inhibitors. The development of the SAR of the series and a detailed discussion around some key parameters monitored and addressed during the lead generation phase will be given. The in vivo results from an oral lipid tolerance test (OLTT) using the MGAT2 inhibitor (S)-10, shows a significant reduction (68% inhibition relative to na?ve, p <0.01) in plasma triacylglycerol (TAG) concentration.     

Cell-associated tumor necrosis factor (TNF) as a killing mechanism of activated cytotoxic macrophages

Different macrophage populations were investigated for their abilities to secrete tumor necrosis factor (TNF) and to lyse TNF-susceptible tumor cells. In this way we could demonstrate that TNF-secretion, although a feature of all activated macrophage populations, is no absolute requirement for the killing of the TNF-sensitive Wehi 164 target. Macrophage cytotoxicity against this cell but not against the TNF-resistant P815 mastocytoma, was completely inhibitable by a specific anti-TNF serum also in the absence of measurable secreted TNF. Moreover the TNF-dependent lysis of tumor cells could also be performed by activated macrophages that had been fixed with paraformaldehyde before the addition of the target cells. In the indirect radioimmunoassay, TNF could be demonstrated on the surface of fixed effector cells. Our results must be interpreted in terms of membrane-associated TNF as the lytic principle for TNF-susceptible tumor cells.