10 research outputs found
Ternatin and improved synthetic variants kill cancer cells by targeting the elongation factor-1A ternary complex.
Cyclic peptide natural products have evolved to exploit diverse protein targets, many of which control essential cellular processes. Inspired by a series of cyclic peptides with partially elucidated structures, we designed synthetic variants of ternatin, a cytotoxic and anti-adipogenic natural product whose molecular mode of action was unknown. The new ternatin variants are cytotoxic toward cancer cells, with up to 500-fold greater potency than ternatin itself. Using a ternatin photo-affinity probe, we identify the translation elongation factor-1A ternary complex (eEF1A·GTP·aminoacyl-tRNA) as a specific target and demonstrate competitive binding by the unrelated natural products, didemnin and cytotrienin. Mutations in domain III of eEF1A prevent ternatin binding and confer resistance to its cytotoxic effects, implicating the adjacent hydrophobic surface as a functional hot spot for eEF1A modulation. We conclude that the eukaryotic elongation factor-1A and its ternary complex with GTP and aminoacyl-tRNA are common targets for the evolution of cytotoxic natural products
Gas flows in galaxies: the relative importance of mergers and bars
Galaxy-galaxy interactions and large scale galaxy bars are usually considered
as the two main mechanisms for driving gas to the centres of galaxies. By using
large samples of galaxy pairs and visually classified bars from the Sloan
Digital Sky Survey (SDSS), we compare the relative efficiency of gas inflows
from these two processes. We use two indicators of gas inflow: star formation
rate (SFR) and gas phase metallicity, which are both measured relative to
control samples. Whereas the metallicity of galaxy pairs is suppressed relative
to its control sample of isolated galaxies, galaxies with bars are metal-rich
for their stellar mass by 0.06 dex over all stellar masses. The SFRs of both
the close galaxy pairs and the barred galaxies are enhanced by ~60%, but in the
bars the enhancement is only seen at stellar masses M* >10^10 M_solar. Taking
into account the relative frequency of bars and pairs, we estimate that at
least three times more central star formation is triggered by bars than by
interactions.Comment: Proceedings of "Tracing the Ancestry of Galaxies on the Land of our
Ancestors", Eds Carignan, Freeman & Combe
Galaxy pairs in the Sloan Digital Sky Survey - IV: Interactions trigger AGN
Galaxy-galaxy interactions are predicted to cause gas inflows leading to
enhanced nuclear star formation. In this paper we test the further prediction
that the gas inflows lead to enhanced accretion onto the central supermassive
black hole, triggering activity in the nucleus. Based on a sample of 11,060
SDSS galaxies with a close companion (rp < 80 kpc, Delta V < 200 km/s), we
classify AGN based either on emission line ratios or on spectral classification
as a quasar. The AGN fraction in the close pairs sample is compared to a
control sample of 110,600 mass- and redshift-matched control galaxies with no
nearby companion. We find a clear increase in the AGN fraction in close pairs
of galaxies with projected separations < 40 kpc by up to a factor of 2.5
relative to the control sample (although the enhancement depends on the chosen
S/N cut of the sample). The increase in AGN fraction is strongest in equal mass
galaxy pairings, and weakest in the lower mass component of an unequal mass
pairing. The increased AGN fraction at small separations is accompanied by an
enhancement in the number of `composite' galaxies whose spectra are the result
of photoionization by both AGN and stars. Our results indicate that AGN
activity occurs (at least in some cases) well before final coalescence and
concurrently with ongoing star formation. Finally, we find a marked increase at
small projected separations of the fraction of pairs in which BOTH galaxies
harbour AGN. We demonstrate that the fraction of double AGN exceeds the
expected random fraction, indicating that some pairs undergo correlated nuclear
activity. Taken together with complimentary studies, we favour an
interpretation where interactions trigger AGN, but are not the only cause of
nuclear activity.Comment: Accepted for publication in MNRA
Identification of 12 new susceptibility loci for different histotypes of epithelial ovarian cancer.
To identify common alleles associated with different histotypes of epithelial ovarian cancer (EOC), we pooled data from multiple genome-wide genotyping projects totaling 25,509 EOC cases and 40,941 controls. We identified nine new susceptibility loci for different EOC histotypes: six for serous EOC histotypes (3q28, 4q32.3, 8q21.11, 10q24.33, 18q11.2 and 22q12.1), two for mucinous EOC (3q22.3 and 9q31.1) and one for endometrioid EOC (5q12.3). We then performed meta-analysis on the results for high-grade serous ovarian cancer with the results from analysis of 31,448 BRCA1 and BRCA2 mutation carriers, including 3,887 mutation carriers with EOC. This identified three additional susceptibility loci at 2q13, 8q24.1 and 12q24.31. Integrated analyses of genes and regulatory biofeatures at each locus predicted candidate susceptibility genes, including OBFC1, a new candidate susceptibility gene for low-grade and borderline serous EOC
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Ternatin and improved synthetic variants kill cancer cells by targeting the elongation factor-1A ternary complex.
Cyclic peptide natural products have evolved to exploit diverse protein targets, many of which control essential cellular processes. Inspired by a series of cyclic peptides with partially elucidated structures, we designed synthetic variants of ternatin, a cytotoxic and anti-adipogenic natural product whose molecular mode of action was unknown. The new ternatin variants are cytotoxic toward cancer cells, with up to 500-fold greater potency than ternatin itself. Using a ternatin photo-affinity probe, we identify the translation elongation factor-1A ternary complex (eEF1A·GTP·aminoacyl-tRNA) as a specific target and demonstrate competitive binding by the unrelated natural products, didemnin and cytotrienin. Mutations in domain III of eEF1A prevent ternatin binding and confer resistance to its cytotoxic effects, implicating the adjacent hydrophobic surface as a functional hot spot for eEF1A modulation. We conclude that the eukaryotic elongation factor-1A and its ternary complex with GTP and aminoacyl-tRNA are common targets for the evolution of cytotoxic natural products
Discovery and in Vivo Evaluation of Dual PI3Kβ/δ Inhibitors
Structure-based rational design led to the synthesis
of a novel series of potent PI3K inhibitors. The optimized pyrrolopyridine
analogue <b>63</b> was a potent and selective PI3Kβ/δ
dual inhibitor that displayed suitable physicochemical properties
and pharmacokinetic profile for animal studies. Analogue <b>63</b> was found to be efficacious in animal models of inflammation including
a keyhole limpet hemocyanin (KLH) study and a collagen-induced arthritis
(CIA) disease model of rheumatoid arthritis. These studies highlight
the potential therapeutic value of inhibiting both the PI3Kβ
and δ isoforms in the treatment of a number of inflammatory
diseases
Identification of 12 new susceptibility loci for different histotypes of epithelial ovarian cancer
To identify common alleles associated with different histotypes of epithelial ovarian cancer (EOC), we pooled data from multiple genome-wide genotyping projects totaling 25,509 EOC cases and 40,941 controls. We identified nine new susceptibility loci for different EOC histotypes: six for serous EOC histotypes (3q28, 4q32.3, 8q21.11, 10q24.33, 18q11.2 and 22q12.1), two for mucinous EOC (3q22.3 and 9q31.1) and one for endometrioid EOC (5q12.3). We then performed meta-analysis on the results for high-grade serous ovarian cancer with the results from analysis of 31,448 BRCA1 and BRCA2 mutation carriers, including 3,887 mutation carriers with EOC. This identified three additional susceptibility loci at 2q13, 8q24.1 and 12q24.31. Integrated analyses of genes and regulatory biofeatures at each locus predicted candidate susceptibility genes, including OBFC1, a new candidate susceptibility gene for low-grade and borderline serous EOC