Synthesis and evaluation of 4-triazolylflavans as new aromatase inhibitors

Aromatase is a target of pharmacological interest for the treatment of estrogen-dependent cancers. Azole derivatives such as letrozole or anastrozole have been developed for aromatase inhibition and are used for the treatment of breast tumors. In this paper, four 4-triazolylflavans were synthesized and were found to exhibit moderate to high inhibitory activity against aromatase.     

Profiling treatment-specific post-translational modifications in a complex proteome with subtractive substrate phage display

Proteolytic activation of zymogens or controlled degradation of inhibitory factors is part of a major regulatory system on the post-translational level to regulate treatment induced cellular stress responses. The identification of differential activity based substrates is thus of high interest to prioritize and validate candidate targets for drug discovery. Here we present a novel subtractive substrate phage display screening method for the selection of treatment induced post-translational peptide modifications in complex proteomes. We investigated this approach with tumor cells in response to a protease activating anticancer treatment modality using subtractive and iterative screening of cellular extracts derived from control and treated cells. Specific phage were identified that served as substrates for proteolytic activities in response to treatment related activity changes and could be distinguished from substrates for unspecific proteolytic background activities. Novel, selected peptide substrates were investigated in vitro and in vivo and showed high substrate specificity and functional biological significance.     

Nucleotide diversity of the <Emphasis Type="Italic">ZmPox3</Emphasis> maize peroxidase gene: Relationships between a MITE insertion in exon 2 and variation in forage maize digestibility

Background  

Polymorphisms were investigated within the ZmPox3 maize peroxidase gene, possibly involved in lignin biosynthesis because of its colocalization with a cluster of QTL related to lignin content and cell wall digestibility. The purpose of this study was to identify, on the basis of 37 maize lines chosen for their varying degrees of cell wall digestibility and representative of temperate regions germplasm, ZmPox3 haplotypes or individual polymorphisms possibly associated with digestibility.     

Geranylgeranyl switching regulates GDI-Rab GTPase recycling

Rab GTPases, key regulators of membrane targeting and fusion, require the covalent attachment of geranylgeranyl lipids to their C terminus for function. To elucidate the role of lipid in Rab recycling, we have determined the crystal structure of Rab guanine nucleotide dissociation inhibitor (alphaGDI) in complex with a geranylgeranyl (GG) ligand (H(2)N-Cys-(S-GG)-OMe). The lipid is bound beneath the Rab binding platform in a shallow hydrophobic groove. Mutation of the binding pocket in the brain-specific alphaGDI leads to mental retardation. Strikingly, lipid binding acts through a conserved allosteric switching mechanism to promote release of the GDI-Rab[GDP] complex from the membrane.     

Prostaglandin D2 affects the maturation of human monocyte-derived dendritic cells: consequence on the polarization of naive Th cells

Among the factors produced at inflammatory sites and those capable of modulating dendritic cell (DC) functions, PGD(2) may be important in the outcome of immune responses. The biological roles for PGD(2) are in part effected through two plasma membrane G protein-coupled receptors: the D prostanoid (DP) receptor and the chemoattractant receptor-homologous molecule expressed on Th2 lymphocytes (CRTH2). In this report, we studied the effects of PGD(2) and of its major physiological metabolite, 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)), on the functions of human monocyte-derived DC. First, we show that PGD(2) exerts in vitro chemotactic effects on monocytes via CRTH2 activation while it inhibits the chemokine-driven migration of monocyte-derived DC through DP. We also report that PGD(2) and 15d-PGJ(2) alter the LPS- and allergen-induced DC maturation and enhance the CD80/CD86 ratio on mature DC in a DP- and CRTH2-independent manner. Moreover, PGD(2) and 15d-PGJ(2) strongly reduce the secretion of the Th1 promoting cytokine IL-12 and affect the synthesis of chemokines involved in Th1 cell chemotaxis, particularly CXCL10. Inhibition of cytokine/chemokine secretion implicates at least in part DP, but not CRTH2. The effects exerted by PGD(2) are associated with the phosphorylation of CREB, but do not parallel with the deactivation of the NF-kappa B and mitogen-activated protein kinase pathways. In contrast, 15d-PGJ(2) seems to target other cellular proteins. Finally, in a model of Th CD45RA(+) differentiation induced by allergen- and superantigen-pulsed DC, PGD(2) impacts on the orientation of the immune response by favoring a Th2 response.     

Regulatory role of arginine 204 in the catalytic activity of rat alloantigens ART2a and ART2b

ART2a (RT6.1) and ART2b (RT6.2) are NAD glycohydrolases (NADases) that are linked to T lymphocytes by glycosylphosphatidylinositol anchors. Although both mature proteins possess three conserved regions (I, II, III) that form the NAD-binding site and differ by only ten amino acids, only ART2b is auto-ADP-ribosylated and only ART2a is glycosylated. To investigate the structural basis for these differences, wild-type and mutant ART2a and ART2b were expressed in rat mammary adenocarcinoma (NMU) cells and released with phosphatidylinositol-specific phospholipase C. All mutants were immunoreactive NADases. Arginine 204 (Arg204), NH2-terminal to essential glutamate 209 in Region III, is found in ART2b, but not ART2a. Replacement of Arg204 in ART2b with lysine, tyrosine, or glutamate abolished auto-ADP-ribosylation. Unlike wild-type ART2a, ART2a(Y204R) was auto-ADP-ribosylated. The tryptophan mutant ART2b(R204W) was auto-ADP-ribosylated and exhibited enhanced NADase activity. Incubation with NAD and auto-ADP-ribosylation decreased the NADase activities of wild-type ART2b and ART2b (R204W), whereas activity of ART2b(R204K), which is not auto-modified, was unchanged by NAD. Facilitation of auto-ADP-ribosylation by tryptophan 204 suggests that the hydrophobic amino acid mimics an ADP-ribosylated arginine. Thus, Arg204 in ART2b serves as a regulatory switch whose presence is required for additional auto-ADP-ribosylation and regulation of catalytic activity.     

MAP kinase-dependent degradation of p27Kip1 by calpains in choroidal melanoma cells. Requirement of p27Kip1 nuclear export

We investigated the status and the regulation of the cyclin-dependent kinases (CDK) inhibitor p27(Kip1) in a choroidal melanoma tumor-derived cell line (OCM-1). By contrast to normal choroidal melanocytes, the expression level of p27(Kip1) was low in these cells and the mitogen-activated protein (MAP) kinase pathway was constitutively activated. Genetic or chemical inhibition of this pathway induced p27(Kip1) accumulation, whereas MAP kinase reactivation triggered a down-regulation of p27(Kip1) that could be partially reversed by calpain inhibitors. In good accordance, ectopic expression of the cellular calpain inhibitor calpastatin led to an increase of endogenous p27(Kip1) expression. In vitro, p27(Kip1) was degraded by calpains, and OCM-1 cell extracts contained a calcium-dependent p27(Kip1) degradation activity. MAP kinase inhibition partially inhibited both calpain activity and calcium-dependent p27(Kip1) degradation by cellular extracts. Immunofluorescence labeling and subcellular fractionation revealed that p27(Kip1) was in part localized in the cytoplasmic compartment of OCM-1 cells but not of melanocytes, and accumulated into the nucleus upon MAP kinase inhibition. MAP kinase activation triggered a cytoplasmic translocation of the protein, as well as a change in its phosphorylation status. This CRM-1-dependent cytoplasmic translocation was necessary for MAP kinase- and calpain-dependent degradation. Taken together, these data suggest that in tumor-derived cells, p27(Kip1) could be degraded by calpains through a MAP kinase-dependent process, and that abnormal cytoplasmic localization of the protein, probably linked to modifications of its phosphorylation state, could be involved in this alternative mechanism of degradation.     

Automated image acquisition for single-particle reconstruction using p97 as the biological sample

We have used Leginon, a fully automatic system capable of acquiring cryo-electron micrographs, to collect data of single particles, specifically of the AAA ATPase p97. The images were acquired under low-dose conditions and required no operator intervention other than the initial setup and periodic refilling of the cold-stage dewar. Each image was acquired at two different defocus values. Two-dimensional projection maps of p97 were calculated from these data and compared to results previously obtained using the conventional manual data collection methods to film. The results demonstrate that Leginon performs as well as an experienced microscopist for the acquisition of single-particle data. The general advantages of automation are discussed.     

Isolation and characterization of six peach cDNAs encoding key proteins in organic acid metabolism and solute accumulation: involvement in regulating peach fruit acidity

As in many other fleshy fruits, the predominant organic acids in ripe peach ( Prunus persica (L.) Batsch) fruit are malic and citric acids. The accumulation of these metabolites in fruit flesh is regulated during fruit development. Six peach fruit-related genes implicated in organic acid metabolism (mitochondrial citrate synthase; cytosolic NAD-dependent malate dehydrogenase, and cytosolic NADP-dependent isocitrate dehydrogenase) and storage (vacuolar proton translocating pumps: one vacuolar H⁺-ATPase, and two vacuolar H⁺-pyrophosphatases) were cloned. Five of these peach genes were homologous to genes isolated from fruit in other fleshy fruit species. Phylogenetic and expression analyses suggested the existence of a particular vacuolar pyrophosphatase highly expressed in fruit. The sixth gene was the first cytosolic NAD-dependent malate dehydrogenase gene isolated from fruit. Gene expression was studied during the fruit development of two peach cultivars, a normal-acid (Fantasia) and a low-acid (Jalousia) cultivar. The overall expression patterns of the organic acid-related genes appeared strikingly similar for the two cultivars. The genes involved in organic acid metabolism showed a stronger expression in ripening fruit than during the earlier phases of development, but their expression patterns were not necessarily correlated with the changes in organic acid contents. The tonoplast proton pumps showed a biphasic expression pattern more consistent with the patterns of organic acid accumulation, and the tonoplast pyrophosphatases were more highly expressed in the fruit of the low-acid cultivar during the second rapid growth phase of the fruit.