Discovery of an ergosterol-signaling factor that regulates Trypanosoma brucei growth

Ergosterol biosynthesis and homeostasis in the parasitic protozoan Trypanosoma brucei was analyzed by RNAi silencing and inhibition of sterol C24β-methyltransferase (TbSMT) and sterol 14α-demethylase [TbSDM (TbCYP51)] to explore the functions of sterols in T. brucei growth. Inhibition of the amount or activity of these enzymes depletes ergosterol from cells at <6 fg/cell for procyclic form (PCF) cells or <0.01 fg/cell for bloodstream form (BSF) cells and reduces infectivity in a mouse model of infection. Silencing of TbSMT expression by RNAi in PCF or BSF in combination with 25-azalanosterol (AZA) inhibited parasite growth and this inhibition was restored completely by adding synergistic cholesterol (7.8 μM from lipid-depleted media) with small amounts of ergosterol (1.2 μM) to the medium. These observations are consistent with the proposed requirement for ergosterol as a signaling factor to spark cell proliferation while imported cholesterol or the endogenously formed cholesta-5,7,24-trienol act as bulk membrane components. To test the potential chemotherapeutic importance of disrupting ergosterol biosynthesis using pairs of mechanism-based inhibitors that block two enzymes in the post-squalene segment, parasites were treated with AZA and itraconazole at 1 μM each (ED₅₀ values) resulting in parasite death. Taken together, our results demonstrate that the ergosterol pathway is a prime drug target for intervention in T. brucei infection.     

Efficient systemic expression of bioactive IL-15 in mice upon delivery of optimized DNA expression plasmids

Efficient expression vectors for interleukin 15 (IL-15) were developed combining RNA/codon optimization and modification of the IL-15 native long signal peptide. These changes resulted in elevated cytoplasmic levels of the optimized mRNA and more than 100-fold improved production of secreted human IL-15 protein. Similar modifications have also led to greatly increased rhesus macaque and murine IL-15 production. Comparison of different heterologous secretory signals showed that the tissue plasminogen activator signal is most efficient for the production of extracellular IL-15. Upon intramuscular injection of the fully optimized expression vectors in mice, IL-15 was readily detected in the serum. Serum levels represented <1% of intramuscular IL-15 and were sufficient in causing some systemic effects, such as increasing the frequency of natural killer (NK) cells in the liver. Upon hydrodynamic DNA delivery in mice, very high levels of IL-15 were produced, which increased the frequency of NK cells in liver as well as in spleen and lung. These optimized expression vectors have potential applications in vaccine and immunotherapy approaches against AIDS and cancer.     

Mutations in cohesin complex members SMC3 and SMC1A cause a mild variant of cornelia de Lange syndrome with predominant mental retardation

Mutations in the cohesin regulators NIPBL and ESCO2 are causative of the Cornelia de Lange syndrome (CdLS) and Roberts or SC phocomelia syndrome, respectively. Recently, mutations in the cohesin complex structural component SMC1A have been identified in two probands with features of CdLS. Here, we report the identification of a mutation in the gene encoding the complementary subunit of the cohesin heterodimer, SMC3, and 14 additional SMC1A mutations. All mutations are predicted to retain an open reading frame, and no truncating mutations were identified. Structural analysis of the mutant SMC3 and SMC1A proteins indicate that all are likely to produce functional cohesin complexes, but we posit that they may alter their chromosome binding dynamics. Our data indicate that SMC3 and SMC1A mutations (1) contribute to approximately 5% of cases of CdLS, (2) result in a consistently mild phenotype with absence of major structural anomalies typically associated with CdLS, and (3) in some instances, result in a phenotype that approaches that of apparently nonsyndromic mental retardation.     

Ligand-based and e-pharmacophore modeling, 3D-QSAR and hierarchical virtual screening to identify dual inhibitors of spleen tyrosine kinase (Syk) and janus kinase 3 (JAK3)

The clinical efficacy of multiple kinase inhibitors has caught the interest of Pharmaceutical and Biotech researchers to develop potential drugs with multi-kinase inhibitory activity for complex diseases. In the present work, we attempted to identify dual inhibitors of spleen tyrosine kinase (Syk) and janus kinase 3 (JAK3), keys players in immune signaling, by developing ideal pharmacophores integrating Ligand-based pharmacophore models (LBPMs) and Structure-based pharmacophore models (SBPMs), thereby projecting the optimum pharmacophoric required for inhibition of both the kinases. The four point LBPM; ADPR.14 suggested the presence of one hydrogen bond acceptor, one hydrogen bond donor, one positive ionizable, and one ring aromatic feature for Syk inhibitory activity and AADH.54 proposed the necessity of two hydrogen bond acceptor, one hydrogen bond donor, and one hydrophobic feature for JAK3 inhibitory activity. To our interest, SBPMs identified additional ring aromatic features required for inhibition of both the kinases. For Syk inhibitory activity, the hydrogen bond acceptor feature indicated by LBPM was devoid of forming hydrogen bonding interaction with the hinge region amino acid residue (Ala451). Thus merging the information revealed by both LBPMs and SBPMs, ideal pharmacophore models i.e. ADPRR.14 (Syk) and AADHR.54 (JAK3) were generated. These models after rigorous statistical validation were used for screening of Asinex database. The systematic virtual screening protocol, including pharmacophore and docking-based screening, ADME property, and MM-GBSA energy calculations, retrieved final 10 hits as dual inhibitors of Syk and JAK3. Final 10 hits thus obtained can aid in the development of potential therapeutic agents for autoimmune disorders. Also the top two hits were evaluated against both the enzymes.     

Coimmunization with an optimized IL-15 plasmid results in enhanced function and longevity of CD8 T cells that are partially independent of CD4 T cell help

DNA vaccines are a promising technology for the induction of Ag-specific immune responses, and much recent attention has gone into improving their immune potency. In this study we test the feasibility of delivering a plasmid encoding IL-15 as a DNA vaccine adjuvant for the induction of improved Ag-specific CD8(+) T cellular immune responses. Because native IL-15 is poorly expressed, we used PCR-based strategies to develop an optimized construct that expresses 80-fold higher than the native IL-15 construct. Using a DNA vaccination model, we determined that immunization with optimized IL-15 in combination with HIV-1gag DNA constructs resulted in a significant enhancement of Ag-specific CD8(+) T cell proliferation and IFN-gamma secretion, and strong induction of long-lived CD8(+) T cell responses. In an influenza DNA vaccine model, coimmunization with plasmid expressing influenza A PR8/34 hemagglutinin with the optimized IL-15 plasmid generated improved long term CD8(+) T cellular immunity and protected the mice against a lethal mucosal challenge with influenza virus. Because we observed that IL-15 appeared to mostly adjuvant CD8(+) T cell function, we show that in the partial, but not total, absence of CD4(+) T cell help, plasmid-delivered IL-15 could restore CD8 secondary immune responses to an antigenic DNA plasmid, supporting the idea that the effects of IL-15 on CD8(+) T cell expansion require the presence of low levels of CD4 T cells. These data suggest a role for enhanced plasmid IL-15 as a candidate adjuvant for vaccine or immunotherapeutic studies.     

Database searching for thymidine and thymidylate kinase inhibitors using three-dimensional structure-based methods

Structure-based drug design methods were used to search for novel inhibitors of herpes simplex virus type 1 (HSV-1) thymidine kinase and Mycobacterium tuberculosis thymidylate kinase. The method involved the use of crystal structure complexes to guide database searching for potential inhibitors. A number of weak inhibitors of HSV-2 were identified, one of which was found to inhibit HSV-1 TK and HSV-1 TK-deficient viral strains. Each compound tested against M. tuberculosis thymidylate kinase was found to have some activity. The best of these compounds was only 4.6-fold less potent than 3'-azido-3'-deoxythymidine-5'-monophosphate (AZTMP). This study demonstrates the utility of structure-based drug design methods in the search for novel enzyme inhibitors.     

NIPBL mutational analysis in 120 individuals with Cornelia de Lange syndrome and evaluation of genotype-phenotype correlations

The Cornelia de Lange syndrome (CdLS) is a multisystem developmental disorder characterized by facial dysmorphia, upper-extremity malformations, hirsutism, cardiac defects, growth and cognitive retardation, and gastrointestinal abnormalities. Both missense and protein-truncating mutations in NIPBL, the human homolog of the Drosophila melanogaster Nipped-B gene, have recently been reported to cause CdLS. The function of NIPBL in mammals is unknown. The Drosophila Nipped-B protein facilitates long-range enhancer-promoter interactions and plays a role in Notch signaling and other developmental pathways, as well as being involved in mitotic sister-chromatid cohesion. We report the spectrum and distribution of NIPBL mutations in a large well-characterized cohort of individuals with CdLS. Mutations were found in 56 (47%) of 120 unrelated individuals with sporadic or familial CdLS. Statistically significant phenotypic differences between mutation-positive and mutation-negative individuals were identified. Analysis also suggested a trend toward a milder phenotype in individuals with missense mutations than in those with other types of mutations.     

Isolation of autosomal mutations in Drosophila melanogaster without setting up lines

Summary Mutants of Drosophila melanogaster are being used increasingly for studying different biological mechanisms. However, most attempts to identify new mutations have been restricted to the X-chromosome. It has been very difficult to identify new loci on the autosomes, as recessive mutations have to be made homozygous by setting up independent cultures for each mutagenized chromosome. We introduce a mutagenesis scheme which does not require setting up independent cultures. It uses meiotic recombination in compound autosomes to make recessive mutations homozygous and allows the screening of tens of thousands of mutagenized chromosomes with relatively little effort. In a pilot experiment, we tested about 33,300 chromosomes for temperature-sensitive paralytic mutations. We obtained 62 independent paralytic mutations and a large number of other mutations. Eight out of 25 of the paralytic mutations are on the autosomes. This method makes autosomes, which constitute about 80% of the Drosophila genome, more accessible for mutational analysis of various biological mechanisms.     

Design and implementation of transaction privacy by virtue of ownership and traceability in blockchain based supply chain

Cluster Computing - Blockchain was at the top of the 2016 Gartner hype cycle and has been integrated into business profiles by numerous start-ups. Since the emergence of blockchain through Bitcoin,...