TY - JOUR A1 - Gassen, Alwine A1 - Brechtefeld, Doris A1 - Schandry, Niklas A1 - Arteaga-Salas, J. Manuel A1 - Israel, Lars A1 - Imhof, Axel A1 - Janzen, Christian J. T1 - DOT1A-dependent H3K76 methylation is required for replication regulation in Trypanosoma brucei JF - Nucleic Acids Research N2 - Cell-cycle progression requires careful regulation to ensure accurate propagation of genetic material to the daughter cells. Although many cell-cycle regulators are evolutionarily conserved in the protozoan parasite Trypanosoma brucei, novel regulatory mechanisms seem to have evolved. Here, we analyse the function of the histone methyltransferase DOT1A during cell-cycle progression. Over-expression of DOT1A generates a population of cells with aneuploid nuclei as well as enucleated cells. Detailed analysis shows that DOT1A over-expression causes continuous replication of the nuclear DNA. In contrast, depletion of DOT1A by RNAi abolishes replication but does not prevent karyokinesis. As histone H3K76 methylation has never been associated with replication control in eukaryotes before, we have discovered a novel function of DOT1 enzymes, which might not be unique to trypanosomes. KW - variants KW - cell-cycle regulation KW - blood-stream forms KW - african trypanosomes KW - mammalian cells KW - DNA replication KW - DOT1 KW - protein KW - transcription KW - cultivation Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-131449 VL - 40 IS - 20 ER - TY - JOUR A1 - Vieira, Jacqueline A1 - Jones, Alex R. A1 - Danon, Antoine A1 - Sakuma, Michiyo A1 - Hoang, Nathalie A1 - Robles, David A1 - Tait, Shirley A1 - Heyes, Derren J. A1 - Picot, Marie A1 - Yoshii, Taishi A1 - Helfrich-Förster, Charlotte A1 - Soubigou, Guillaume A1 - Coppee, Jean-Yves A1 - Klarsfeld, André A1 - Rouyer, Francois A1 - Scrutton, Nigel S. A1 - Ahmad, Margaret T1 - Human Cryptochrome-1 Confers Light Independent Biological Activity in Transgenic Drosophila Correlated with Flavin Radical Stability JF - PLoS One N2 - Cryptochromes are conserved flavoprotein receptors found throughout the biological kingdom with diversified roles in plant development and entrainment of the circadian clock in animals. Light perception is proposed to occur through flavin radical formation that correlates with biological activity in vivo in both plants and Drosophila. By contrast, mammalian (Type II) cryptochromes regulate the circadian clock independently of light, raising the fundamental question of whether mammalian cryptochromes have evolved entirely distinct signaling mechanisms. Here we show by developmental and transcriptome analysis that Homo sapiens cryptochrome - 1 (HsCRY1) confers biological activity in transgenic expressing Drosophila in darkness, that can in some cases be further stimulated by light. In contrast to all other cryptochromes, purified recombinant HsCRY1 protein was stably isolated in the anionic radical flavin state, containing only a small proportion of oxidized flavin which could be reduced by illumination. We conclude that animal Type I and Type II cryptochromes may both have signaling mechanisms involving formation of a flavin radical signaling state, and that light independent activity of Type II cryptochromes is a consequence of dark accumulation of this redox form in vivo rather than of a fundamental difference in signaling mechanism. KW - arabidopsi KW - dependent magnetosensitvity KW - protein KW - clock KW - gene KW - mechanism KW - rhythm KW - oscillator KW - circadian photoreception KW - mammalian CRY1 Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-134513 VL - 7 IS - 3 ER - TY - JOUR A1 - Buga, Ana-Maria A1 - Scholz, Claus Jürgen A1 - Kumar, Senthil A1 - Herndon, James G. A1 - Alexandru, Dragos A1 - Cojocaru, Gabriel Radu A1 - Dandekar, Thomas A1 - Popa-Wagner, Aurel T1 - Identification of New Therapeutic Targets by Genome-Wide Analysis of Gene Expression in the Ipsilateral Cortex of Aged Rats after Stroke JF - PLoS One N2 - Background: Because most human stroke victims are elderly, studies of experimental stroke in the aged rather than the young rat model may be optimal for identifying clinically relevant cellular responses, as well for pinpointing beneficial interventions. Methodology/Principal Findings: We employed the Affymetrix platform to analyze the whole-gene transcriptome following temporary ligation of the middle cerebral artery in aged and young rats. The correspondence, heat map, and dendrogram analyses independently suggest a differential, age-group-specific behaviour of major gene clusters after stroke. Overall, the pattern of gene expression strongly suggests that the response of the aged rat brain is qualitatively rather than quantitatively different from the young, i.e. the total number of regulated genes is comparable in the two age groups, but the aged rats had great difficulty in mounting a timely response to stroke. Our study indicates that four genes related to neuropathic syndrome, stress, anxiety disorders and depression (Acvr1c, Cort, Htr2b and Pnoc) may have impaired response to stroke in aged rats. New therapeutic options in aged rats may also include Calcrl, Cyp11b1, Prcp, Cebpa, Cfd, Gpnmb, Fcgr2b, Fcgr3a, Tnfrsf26, Adam 17 and Mmp14. An unexpected target is the enzyme 3-hydroxy-3-methylglutaryl-Coenzyme A synthase 1 in aged rats, a key enzyme in the cholesterol synthesis pathway. Post-stroke axonal growth was compromised in both age groups. Conclusion/Significance: We suggest that a multi-stage, multimodal treatment in aged animals may be more likely to produce positive results. Such a therapeutic approach should be focused on tissue restoration but should also address other aspects of patient post-stroke therapy such as neuropathic syndrome, stress, anxiety disorders, depression, neurotransmission and blood pressure. KW - gamma KW - corticotropin-releasing hormone KW - colony-stimulating factor KW - cerebral ischemia KW - receptor KW - brain KW - protein KW - inhibitor KW - mouse KW - differentiation Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-130657 VL - 7 IS - 12 ER - TY - JOUR A1 - Harrington, John M. A1 - Scelsi, Chris A1 - Hartel, Andreas A1 - Jones, Nicola G. A1 - Engstler, Markus A1 - Capewell, Paul A1 - MacLeod, Annette A1 - Hajduk, Stephen T1 - Novel African Trypanocidal Agents: Membrane Rigidifying Peptides JF - PLoS One N2 - The bloodstream developmental forms of pathogenic African trypanosomes are uniquely susceptible to killing by small hydrophobic peptides. Trypanocidal activity is conferred by peptide hydrophobicity and charge distribution and results from increased rigidity of the plasma membrane. Structural analysis of lipid-associated peptide suggests a mechanism of phospholipid clamping in which an internal hydrophobic bulge anchors the peptide in the membrane and positively charged moieties at the termini coordinate phosphates of the polar lipid headgroups. This mechanism reveals a necessary phenotype in bloodstream form African trypanosomes, high membrane fluidity, and we suggest that targeting the plasma membrane lipid bilayer as a whole may be a novel strategy for the development of new pharmaceutical agents. Additionally, the peptides we have described may be valuable tools for probing the biosynthetic machinery responsible for the unique composition and characteristics of African trypanosome plasma membranes. KW - depth KW - trypanosome lytic factor KW - signal peptides KW - cell surface KW - protein KW - brucei KW - environment KW - bilayers KW - binding KW - probes Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-135179 VL - 7 IS - 9 ER -