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De Simone F.,Ecole Polytechnique Federale de Lausanne | Gertsch J.,Institute of Biochemistry and Molecular Medicine | Waser J.,Ecole Polytechnique Federale de Lausanne
Angewandte Chemie - International Edition | Year: 2010

(Figure Presented) Mild control: Selective cyclization of aminocyclopropanes at either the N1 or C3 position of an indole ring was achieved by tuning the reaction conditions (see scheme). This strategy was applied to the formal synthesis of aspidospermidine and the total synthesis of goniomitine, which demonstrated significant cytotoxicity against several tumor cell lines (IC50 = 150-400 nM). Cbz = benzyloxycarbonyl, Ts = 4-toluenesulfonyl. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Leonti M.,University of Cagliari | Casu L.,University of Cagliari | Solinas M.N.,University of Cagliari | Cottiglia F.,University of Cagliari | And 4 more authors.
Natural Product Communications | Year: 2010

Chemical investigation of the stems of Seseli praecox (Gamisans) Gamisans, an endemic Apiaceae from Sardinia, afforded an isopropenylated chromone (5-hydroxy-6-(2-Z-butenyl-3-hydroxymethyl)-7-methoxy-2-methylchromone), along with four known linear furocoumarins and their natural precursor. For biological characterization the new compound was screened against four cancer cell lines in vitro and showed differential μM antiproliferative effects between suspension and adherent cells. Source

Tamborrini M.,Swiss Tropical and Public Health Institute | Tamborrini M.,University of Basel | Bauer M.,Swiss Tropical and Public Health Institute | Bauer M.,University of Basel | And 16 more authors.
Journal of Bacteriology | Year: 2011

The surfaces of Bacillus anthracis endospores expose a pentasaccharide containing the monosaccharide anthrose, which has been considered for use as a vaccine or target for specific detection of the spores. In this study B. anthracis strains isolated from cattle carcasses in African countries where anthrax is endemic were tested for their cross-reactivity with monoclonal antibodies (MAbs) specific for anthrose-containing oligosaccharides. Unexpectedly, none of the isolates collected in Chad, Cameroon, and Mali were recognized by the MAbs. Sequencing of the four-gene operon encoding anthrose biosynthetic enzymes revealed the presence of premature stop codons in the aminotransferase and glycosyltransferase genes in all isolates from Chad, Cameroon, and Mali. Both immunological and genetic findings suggest that the West African isolates are unable to produce anthrose. The anthrose-deficient strains from West Africa belong to a particular genetic lineage. Immunization of cattle in Chad with a locally produced vaccine based on anthrose-positive spores of the B. anthracis strain Sterne elicited an anti-carbohydrate IgG response specific for a synthetic anthrosecontaining tetrasaccharide as demonstrated by glycan microarray analysis. Competition immunoblots with synthetic pentasaccharide derivatives suggested an immunodominant role of the anthrose-containing carbohydrate in cattle. In West Africa anthrax is highly endemic. Massive vaccination of livestock in this area has taken place over long periods of time using spores of the anthrose-positive vaccine strain Sterne. The spread of anthrose-deficient strains in this region may represent an escape strategy of B. anthracis. © 2011, American Society for Microbiology. Source

Simonin A.,University of Bern | Simonin A.,Institute of Biochemistry and Molecular Medicine | Fuster D.,University of Bern | Fuster D.,Institute of Biochemistry and Molecular Medicine
Journal of Biological Chemistry | Year: 2010

The ubiquitously expressed mammalian Na+/H+ exchanger 1 (NHE1) controls cell volume and pH but is also critically involved in complex biological processes like cell adhesion, cell migration, cell proliferation, and mechanosensation. Pathways controlling NHE1 turnover at the plasma membrane, however, are currently unclear. Here, we demonstrate that NHE1 undergoes ubiquitylation at the plasma membrane by a process that is unprecedented for a mammalian ion transport protein. This process requires the adapter protein β-arrestin-1 that interacts with both the E3 ubiquitin ligase Nedd4-1 and the NHE1 C terminus. Truncation of NHE1 C terminus to amino acid 550 abolishes binding to β-arrestin-1 and NHE1 ubiquitylation. Overexpression of β-arrestin-1 or of wild type but not ligase-dead Nedd4-1 increases NHE1 ubiquitylation. siRNA-mediated knockdown of Nedd4-1 or β-arrestin-1 reduces NHE1 ubiquitylation and endocytosis leading to increased NHE1 surface levels. Fibroblasts derived from β-arrestin-1 and Nedd4-1 knock-out mice show loss of NHE1 ubiquitylation, increased plasmalemmal NHE1 levels and greatly enhanced NHE1 transport compared with wild-type fibroblasts. These findings reveal Nedd4-1 and β-arrestin-1 as key regulators of NHE1 ubiquitylation, endocytosis, and function. Our data suggest a broader role for β-arrestins in the regulation of membrane ion transport proteins than currently known. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc. Source

Baumann M.,Institute of Biochemistry and Molecular Medicine | Baumann M.,University of Bern | Korner M.,University of Bern | Huang X.,Institute of Biochemistry and Molecular Medicine | And 6 more authors.
Placenta | Year: 2013

Introduction Transplacental feto-maternal lipid exchange through the ATP-binding cassette transporters ABCA1 and ABCG1 is important for normal fetal development. However, only scarce and conflicting data exist on the involvement of these transporters in gestational disease. Methods Placenta samples (n = 72) derived from common gestational diseases, including pre-eclampsia (PE), HELLP, intrauterine growth restriction (IUGR), intrahepatic cholestasis of pregnancy and gestational diabetes, were assessed for their ABCA1 and ABCG1 expression levels and compared to age-matched control placentas with qRT-PCR and immunohistochemistry. ABCA1 expression was additionally investigated with immunoblot in placental membrane vesicles. Furthermore, placental cholesterol and phospholipid contents were assessed. Results ABCA1 mRNA levels differed significantly between preterm and term control placentas (p = 0.0013). They were down-regulated in isolated PE and PE with IUGR (p = 0.0006 and p = 0.0012, respectively), but unchanged in isolated IUGR, isolated HELLP and other gestational diseases compared to gestational age-matched controls. Correspondingly, in PE, ABCA1 protein expression was significantly reduced in the apical membrane of the villous syncytiotrophoblast (p = 0.011) and in villous fetal endothelial cells (p = 0.036). Furthermore, in PE there was a significant increase in the placental content of total and individual classes of phospholipids which were partially correlated with diminished ABCA1 expression. Conversely, ABCG1 mRNA and protein levels were stable in the investigated conditions. Conclusions In gestational disease, there is a specific down-regulation of placental ABCA1 expression at sites of feto-maternal lipid exchange in PE. At a functional level, the increase in placental lipid concentrations provides indirect evidence of an impaired transport capacity of ABCA1 in this disease. © 2013 Elsevier Ltd. All rights reserved. Source

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