@article{FischerHelfrichFoersterPeschel2016,
  author    = {Fischer, Robin and Helfrich-F{\"o}rster, Charlotte and Peschel, Nicolai},
  title     = {GSK-3 Beta Does Not Stabilize Cryptochrome in the Circadian Clock of Drosophila},
  series = {PLoS ONE},
  volume    = {11},
  journal   = {PLoS ONE},
  number    = {1},
  doi       = {10.1371/journal.pone.0146571},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-180370},
  year      = {2016},
  abstract  = {Cryptochrome (CRY) is the primary photoreceptor of Drosophila's circadian clock. It resets the circadian clock by promoting light-induced degradation of the clock protein Timeless (TIM) in the proteasome. Under constant light, the clock stops because TIM is absent, and the flies become arrhythmic. In addition to TIM degradation, light also induces CRY degradation. This depends on the interaction of CRY with several proteins such as the E3 ubiquitin ligases Jetlag (JET) and Ramshackle (BRWD3). However, CRY can seemingly also be stabilized by interaction with the kinase Shaggy (SGG), the GSK-3 beta fly orthologue. Consequently, flies with SGG overexpression in certain dorsal clock neurons are reported to remain rhythmic under constant light. We were interested in the interaction between CRY, Ramshackle and SGG and started to perform protein interaction studies in S2 cells. To our surprise, we were not able to replicate the results, that SGG overexpression does stabilize CRY, neither in S2 cells nor in the relevant clock neurons. SGG rather does the contrary. Furthermore, flies with SGG overexpression in the dorsal clock neurons became arrhythmic as did wild-type flies. Nevertheless, we could reproduce the published interaction of SGG with TIM, since flies with SGG overexpression in the lateral clock neurons shortened their free-running period. We conclude that SGG does not directly interact with CRY but rather with TIM. Furthermore we could demonstrate, that an unspecific antibody explains the observed stabilization effects on CRY.},
  language  = {en}
}
@article{KoenigWolfHeisenberg2016,
  author    = {Koenig, Sebastian and Wolf, Reinhard and Heisenberg, Martin},
  title     = {Visual Attention in Flies-Dopamine in the Mushroom Bodies Mediates the After-Effect of Cueing},
  series = {PLoS ONE},
  volume    = {11},
  journal   = {PLoS ONE},
  number    = {8},
  doi       = {10.1371/journal.pone.0161412},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-179564},
  year      = {2016},
  abstract  = {Visual environments may simultaneously comprise stimuli of different significance. Often such stimuli require incompatible responses. Selective visual attention allows an animal to respond exclusively to the stimuli at a certain location in the visual field. In the process of establishing its focus of attention the animal can be influenced by external cues. Here we characterize the behavioral properties and neural mechanism of cueing in the fly Drosophila melanogaster. A cue can be attractive, repulsive or ineffective depending upon (e.g.) its visual properties and location in the visual field. Dopamine signaling in the brain is required to maintain the effect of cueing once the cue has disappeared. Raising or lowering dopamine at the synapse abolishes this after-effect. Specifically, dopamine is necessary and sufficient in the αβ-lobes of the mushroom bodies. Evidence is provided for an involvement of the αβ\(_{posterior}\) Kenyon cells.},
  language  = {en}
}
@article{Kramer2017,
  author    = {Kramer, Susanne},
  title     = {The ApaH-like phosphatase TbALPH1 is the major mRNA decapping enzyme of trypanosomes},
  series = {PLoS Pathogens},
  volume    = {13},
  journal   = {PLoS Pathogens},
  number    = {6},
  doi       = {10.1371/journal.ppat.1006456},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-158482},
  pages     = {e1006456},
  year      = {2017},
  abstract  = {5'-3' decay is the major mRNA decay pathway in many eukaryotes, including trypanosomes. After deadenylation, mRNAs are decapped by the nudix hydrolase DCP2 of the decapping complex and finally degraded by the 5'-3' exoribonuclease. Uniquely, trypanosomes lack homologues to all subunits of the decapping complex, while deadenylation and 5'-3' degradation are conserved. Here, I show that the parasites use an ApaH-like phosphatase (ALPH1) as their major mRNA decapping enzyme. The protein was recently identified as a novel trypanosome stress granule protein and as involved in mRNA binding. A fraction of ALPH1 co-localises exclusively with the trypanosome 5'-3' exoribonuclease XRNA to a special granule at the posterior pole of the cell, indicating a connection between the two enzymes. RNAi depletion of ALPH1 is lethal and causes a massive increase in total mRNAs that are deadenylated, but have not yet started 5'-3' decay. These data suggest that ALPH1 acts downstream of deadenylation and upstream of mRNA degradation, consistent with a function in mRNA decapping. In vitro experiments show that recombinant, N-terminally truncated ALHP1 protein, but not a catalytically inactive mutant, sensitises the capped trypanosome spliced leader RNA to yeast Xrn1, but only if an RNA 5' polyphosphatase is included. This indicates that the decapping mechanism of ALPH1 differs from the decapping mechanism of Dcp2 by leaving more than one phosphate group at the mRNA's 5' end. This is the first reported function of a eukaryotic ApaH-like phosphatase, a bacterial-derived class of enzymes present in all phylogenetic super-groups of the eukaryotic kingdom. The substrates of eukaryotic ApaH-like phosphatases are unknown. However, the substrate of the related bacterial enzyme ApaH, diadenosine tetraphosphate, is highly reminiscent of a eukaryotic mRNA cap.},
  language  = {en}
}
@phdthesis{Lim2007,
  author    = {Lim, Hee-Young},
  title     = {Functional studies of GR and MR function by RNA interference},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-23646},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2007},
  abstract  = {Die Steroidhormone Corticosteron/Cortisol und Aldosteron werden in Folge von Stress oder eines ver{\"a}nderten Salz-Wasser-Haushalt durch die Nebenniere synthetisiert und sezerniert. Dies wird durch negative R{\"u}ckkopplungsmechanismen kontrolliert, die als HPA-Achse und RAAS bezeichnet werden. Die Aktivit{\"a}t dieser Steroidhormone wird durch den Glukokortikoid Rezeptor (GR) und den Mineralokortikoid-Rezeptor (MR) vermittelt, die im Zytosol als Komplex mit Hitze-Schock-Proteinen vorliegen. Sowohl der GR als auch der MR geh{\"o}ren zur Kern-Rezeptor Superfamilie und besitzen eine gemeinsame Proteinstruktur die aus drei verschiedenen Dom{\"a}nen besteht. Trotzdem haben sie verschiedene Affinit{\"a}ten f{\"u}r ihre Liganden, ihre Aktivit{\"a}t h{\"a}ngt von der Hormonkonzentration ab, sie werden durch Pr{\"a}-Rezeptor-Mechansimen wie der 11b-HSD2 reguliert und ihre Gewebeverteilung ist unterschiedlich. Aldosteron wirkt in epithelialen und nicht-epithelialen Zellen {\"u}ber den MR und reguliert den Salz-Wasser-Haushalt, die Herzfunktion, die neuronale Erregbarkeit und die Adipozyten-Differenzierung. Bislang war die Analyse der Geninaktivierung in vivo auf M{\"a}use beschr{\"a}nkt, obwohl Krankheitsmodelle in der Ratte die Verh{\"a}ltnisse im Menschen manchmal besser widerspiegeln. Da embryonale Stammzellen und damit die gezielte Genmanipulation in Ratten nicht verf{\"u}gbar sind, haben wir MR knock-down Ratten mittels lentiviral eingef{\"u}hrter shRNAs hergestellt. Die F1 Nachkommen der Gr{\"u}nder-Ratten zeigten unterschiedlich stark reduzierte MR mRNA und Protein Niveaus in Niere und Hippocampus, den Hauptexpressions-Regionen des MR. Im Gegensatz dazu war die Expression des GR unver{\"a}ndert, was die Spezifit{\"a}t der Geninaktivierung belegt. Die zwei MR Zielgene Sgk1 und ENaC waren hochreguliert w{\"a}hrend die mRNA Spiegel anderer Gene wie IK1 und SCD2 erniedrigt waren. {\"A}hnlich wie in den knock-out M{\"a}usen und Patienten zeigten die knock-down Ratten die typischen Merkmale des Pseudohypoaldosteronismus Typ I wie erh{\"o}hte Serumspiegel von Aldosteron und Renin sowie Wachstumsretardation. Weiterhin fanden wir einen linearen Zusammenhang zwischen der MR Expression in der Niere, den Serum Aldosteron-Werten und dem K{\"o}rpergewicht. Zusammengefasst sind unsere MR knock-down Ratten unter den ersten Beispielen f{\"u}r RNAi in vivo und belegen, dass diese Technik es erlaubt, abgestufte Auspr{\"a}gugen der Geninktivierung wie in humanen genetischen Erkrankungen zu erreichen. Weiterhin haben wir die Rolle des GR und des MR f{\"u}r die immunmodulatorische Aktivit{\"a}t der Glukokortikoide in peritonealen Makrophagen untersucht. GCs sind an der Kontrolle der Makrophagenfunktion beteiligt und regulieren so die Reaktion gegen{\"u}ber Pathogenen. Aus diesem Grund werden GCs weitverbreitet zur Behandlung von Enz{\"u}ndungen und Autoimmunerkrankungen eingesetzt. Allerdings ist bez{\"u}glich dieser GC Aktivit{\"a}ten weder bekannt welche Kontrolle die Hormonkonzentration spielt noch kennt man den differentiellen Beitrag des GR und des MR. Zuerst best{\"a}tigten wir die Expression beider Rezeptoren in peritonealen Makrophagen w{\"a}hrend die 11b-HSD2 nicht exprimiert war. Anschließend zeigten wir, dass niedrigte Corticosteron-Level die NO Produktion sowie die mRNA Expression von pro-inflammatorischen Zytokinen, Chemokinen und Enzymen die f{\"u}r die Mediator-Synthesee ben{\"o}tigt werden erh{\"o}hen. Im Gegensatz dazu war die Makrophagen Funktion bei hohen Corticosteron-Konzentrationen stark reprimiert. Eine wichtige Beobachtung war, dass die Inaktivierung des GR durch lentiviral eingef{\"u}hrte siRNAs sowohl die immunstimulatorischen als auch die immunsuppressiven GR Aktivit{\"a}ten aufhob w{\"a}hrend die Inaktivierung des MR keine Konsequenzen hatte. Weiterhin f{\"u}hrte der Verlust endogenener GCs nach Adrenalektomie in vivo zu einem pr{\"a}-aktivierten Zustand der Makrophagen, welcher durch Corticosteron moduliert werden konnte. Wir schließen hieraus, dass GCs in Abh{\"a}ngigkeit von ihrer Konzentration unterschiedliche Effekte auf die Makrophagen Funktion haben und dass diese durch den GR vermittelt werden, obwohl der MR ebenfalls exprimiert ist. Zusammengefasst best{\"a}tigen unsere Ergebnisse dass die lenivirale Transduktion von shRNAs eine effiziente Methode zur Geninaktivierung in prim{\"a}ren Zellen und transgenen Ratten darstellt und es so erlaubt, funktionelle Studien durchzuf{\"u}hren die zuvor auf M{\"a}use beschr{\"a}nkt waren.},
  language  = {en}
}
@article{VellmerHartlebFraderaSolaetal.2022,
  author    = {Vellmer, Tim and Hartleb, Laura and Fradera Sola, Albert and Kramer, Susanne and Meyer-Natus, Elisabeth and Butter, Falk and Janzen, Christian J.},
  title     = {A novel SNF2 ATPase complex in Trypanosoma brucei with a role in H2A.Z-mediated chromatin remodelling},
  series = {PLoS Pathogens},
  volume    = {18},
  journal   = {PLoS Pathogens},
  number    = {6},
  doi       = {10.1371/journal.ppat.1010514},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-301372},
  year      = {2022},
  abstract  = {A cascade of histone acetylation events with subsequent incorporation of a histone H2A variant plays an essential part in transcription regulation in various model organisms. A key player in this cascade is the chromatin remodelling complex SWR1, which replaces the canonical histone H2A with its variant H2A.Z. Transcriptional regulation of polycistronic transcription units in the unicellular parasite Trypanosoma brucei has been shown to be highly dependent on acetylation of H2A.Z, which is mediated by the histone-acetyltransferase HAT2. The chromatin remodelling complex which mediates H2A.Z incorporation is not known and an SWR1 orthologue in trypanosomes has not yet been reported. In this study, we identified and characterised an SWR1-like remodeller complex in T. brucei that is responsible for Pol II-dependent transcriptional regulation. Bioinformatic analysis of potential SNF2 DEAD/Box helicases, the key component of SWR1 complexes, identified a 1211 amino acids-long protein that exhibits key structural characteristics of the SWR1 subfamily. Systematic protein-protein interaction analysis revealed the existence of a novel complex exhibiting key features of an SWR1-like chromatin remodeller. RNAi-mediated depletion of the ATPase subunit of this complex resulted in a significant reduction of H2A.Z incorporation at transcription start sites and a subsequent decrease of steady-state mRNA levels. Furthermore, depletion of SWR1 and RNA-polymerase II (Pol II) caused massive chromatin condensation. The potential function of several proteins associated with the SWR1-like complex and with HAT2, the key factor of H2A.Z incorporation, is discussed.},
  language  = {en}
}