TY  - JOUR
A1  - Rajab, Suhaila
A1  - Bismin, Leah
A1  - Schwarze, Simone
A1  - Pinggera, Alexandra
A1  - Greger, Ingo H.
A1  - Neuweiler, Hannes
T1  - Allosteric coupling of sub-millisecond clamshell motions in ionotropic glutamate receptor ligand-binding domains
JF  - Communications Biology
N2  - Ionotropic glutamate receptors (iGluRs) mediate signal transmission in the brain and are important drug targets. Structural studies show snapshots of iGluRs, which provide a mechanistic understanding of gating, yet the rapid motions driving the receptor machinery are largely elusive. Here we detect kinetics of conformational change of isolated clamshell-shaped ligand-binding domains (LBDs) from the three major iGluR sub-types, which initiate gating upon binding of agonists. We design fluorescence probes to measure domain motions through nanosecond fluorescence correlation spectroscopy. We observe a broad kinetic spectrum of LBD dynamics that underlie activation of iGluRs. Microsecond clamshell motions slow upon dimerization and freeze upon binding of full and partial agonists. We uncover allosteric coupling within NMDA LBD hetero-dimers, where binding of L-glutamate to the GluN2A LBD stalls clamshell motions of the glycine-binding GluN1 LBD. Our results reveal rapid LBD dynamics across iGluRs and suggest a mechanism of negative allosteric cooperativity in NMDA receptors.
KW  - fluorescence spectroscopy
KW  - kinetics
KW  - ligand-gated ion channels
KW  - molecular neuroscience
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-261678
VL  - 4
IS  - 1
ER  - 
TY  - JOUR
A1  - Salehi, Saeede
A1  - Zare, Abdolhossein
A1  - Prezza, Gianluca
A1  - Bader, Jakob
A1  - Schneider, Cornelius
A1  - Fischer, Utz
A1  - Meissner, Felix
A1  - Mann, Matthias
A1  - Briese, Michael
A1  - Sendtner, Michael
T1  - Cytosolic Ptbp2 modulates axon growth in motoneurons through axonal localization and translation of Hnrnpr
JF  - Nature Communications
N2  - The neuronal RNA-binding protein Ptbp2 regulates neuronal differentiation by modulating alternative splicing programs in the nucleus. Such programs contribute to axonogenesis by adjusting the levels of protein isoforms involved in axon growth and branching. While its functions in alternative splicing have been described in detail, cytosolic roles of Ptbp2 for axon growth have remained elusive. Here, we show that Ptbp2 is located in the cytosol including axons and growth cones of motoneurons, and that depletion of cytosolic Ptbp2 affects axon growth. We identify Ptbp2 as a major interactor of the 3’ UTR of Hnrnpr mRNA encoding the RNA-binding protein hnRNP R. Axonal localization of Hnrnpr mRNA and local synthesis of hnRNP R protein are strongly reduced when Ptbp2 is depleted, leading to defective axon growth. Ptbp2 regulates hnRNP R translation by mediating the association of Hnrnpr with ribosomes in a manner dependent on the translation factor eIF5A2. Our data thus suggest a mechanism whereby cytosolic Ptbp2 modulates axon growth by fine-tuning the mRNA transport and local synthesis of an RNA-binding protein.
KW  - molecular neuroscience
KW  - RNA-binding proteins
KW  - RNA transport
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-357639
VL  - 14
ER  - 
TY  - THES
A1  - Backhaus, Philipp
T1  - Effects of Transgenic Expression of Botulinum Toxins in Drosophila
T1  - Effekte der transgenen Expression von Botulinumtoxinen in Drosophila
N2  - Clostridial neurotoxins (botulinum toxins and tetanus toxin) disrupt neurotransmitter release by cleaving neuronal SNARE proteins. We generated transgenic flies allowing for conditional expression of different botulinum toxins and evaluated their potential as tools for the analysis of synaptic and neuronal network function in Drosophila melanogaster by applying biochemical assays and behavioral analysis. On the biochemical level, cleavage assays in cultured Drosophila S2 cells were performed and the cleavage efficiency was assessed via western blot analysis. We found that each botulinum toxin cleaves its Drosophila SNARE substrate but with variable efficiency. To investigate the cleavage efficiency in vivo, we examined lethality, larval peristaltic movements and vision dependent motion behavior of adult Drosophila after tissue-specific conditional botulinum toxin expression. Our results show that botulinum toxin type B and botulinum toxin type C represent effective alternatives to established transgenic effectors, i.e. tetanus toxin, interfering with neuronal and non-neuronal cell function in Drosophila and constitute valuable tools for the analysis of synaptic and network function.
N2  - Die verschiedenen Toxine der Bakterienspezies Clostridium (Botulinumtoxine und Tetanustoxin) interferieren mit Neuroexozytose durch Proteolyse der SNARE-Proteine. Wir haben transgene Fliegen generiert, die die Möglichkeit bieten konditional verschiedene Botulinumtoxine zu exprimieren. Durch biochemische Untersuchungen und Verhaltensexperimente haben wir das Potential dieser Toxine als Werkzeuge für die Analyse von Synapsen- und Netzwerkfunktion in Drosophila evaluiert. Durch Western Blot-Analysen stellten wir eine variierende Proteolysierbarkeit der Drosophila SNARE-Substrate durch die verschiedenen Botulinumtoxine dar. In Vivo untersuchten wir die Auswirkungen einer Zell-spezifischen Expression auf die Motorik in Larven und auf die Sehfähigkeit in adulten Fliegen. Unsere Resultate zeigen, dass Botulinumtoxin Typ B und C vielversprechende Alternativen zu etablierten molekularen Werkzeugen, wie Tetanustoxin, darstellen, um synaptische Transmission oder höhere Netzwerkfunktionen aufzuschlüsseln. Hierbei führt Botulinumtoxin Typ B zu einem spezifischen Verlust von neuronaler Aktivität, während Botulinumtoxin Typ C mit nicht Neuronen-spezifischer Zellfunktion interferiert.
KW  - Botulinustoxin
KW  - Drosophila
KW  - Synaptische Transmission
KW  - Behavioral neuroscience
KW  - molecular neuroscience
KW  - neurotoxins
KW  - SNARE proteins
KW  - neurotransmission
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-143279
ER  - 
TY  - JOUR
A1  - Lüffe, Teresa M.
A1  - D'Orazio, Andrea
A1  - Bauer, Moritz
A1  - Gioga, Zoi
A1  - Schoeffler, Victoria
A1  - Lesch, Klaus-Peter
A1  - Romanos, Marcel
A1  - Drepper, Carsten
A1  - Lillesaar, Christina
T1  - Increased locomotor activity via regulation of GABAergic signalling in foxp2 mutant zebrafish – implications for neurodevelopmental disorders
JF  - Translational Psychiatry
N2  - Recent advances in the genetics of neurodevelopmental disorders (NDDs) have identified the transcription factor FOXP2 as one of numerous risk genes, e.g. in autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD). FOXP2 function is suggested to be involved in GABAergic signalling and numerous studies demonstrate that GABAergic function is altered in NDDs, thus disrupting the excitation/inhibition balance. Interestingly, GABAergic signalling components, including glutamate-decarboxylase 1 (Gad1) and GABA receptors, are putative transcriptional targets of FOXP2. However, the specific role of FOXP2 in the pathomechanism of NDDs remains elusive. Here we test the hypothesis that Foxp2 affects behavioural dimensions via GABAergic signalling using zebrafish as model organism. We demonstrate that foxp2 is expressed by a subset of GABAergic neurons located in brain regions involved in motor functions, including the subpallium, posterior tuberculum, thalamus and medulla oblongata. Using CRISPR/Cas9 gene-editing we generated a novel foxp2 zebrafish loss-of-function mutant that exhibits increased locomotor activity. Further, genetic and/or pharmacological disruption of Gad1 or GABA-A receptors causes increased locomotor activity, resembling the phenotype of foxp2 mutants. Application of muscimol, a GABA-A receptor agonist, rescues the hyperactive phenotype induced by the foxp2 loss-of-function. By reverse translation of the therapeutic effect on hyperactive behaviour exerted by methylphenidate, we note that application of methylphenidate evokes different responses in wildtype compared to foxp2 or gad1b loss-of-function animals. Together, our findings support the hypothesis that foxp2 regulates locomotor activity via GABAergic signalling. This provides one targetable mechanism, which may contribute to behavioural phenotypes commonly observed in NDDs.
KW  - comparative genomics
KW  - molecular neuroscience
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-264713
VL  - 11
ER  - 
TY  - JOUR
A1  - Mitjans, M.
A1  - Begemann, M.
A1  - Ju, A.
A1  - Dere, E.
A1  - Wüstefeld, L.
A1  - Hofer, S.
A1  - Hassouna, I.
A1  - Balkenhol, J.
A1  - Oliveira, B.
A1  - Van der Auwera, S.
A1  - Tammer, R.
A1  - Hammerschmidt, K.
A1  - Völzke, H.
A1  - Homuth, G.
A1  - Cecconi, F.
A1  - Chowdhury, K.
A1  - Grabe, H.
A1  - Frahm, J.
A1  - Boretius, S.
A1  - Dandekar, T.
A1  - Ehrenreich, H.
T1  - Sexual dimorphism of \(AMBRA1\)-related autistic features in human and mouse
JF  - Translational Psychiatry
N2  - \(Ambra1\) is linked to autophagy and neurodevelopment. Heterozygous \(Ambra1\) deficiency induces autism-like behavior in a sexually dimorphic manner. Extraordinarily, autistic features are seen in female mice only, combined with stronger Ambra1 protein reduction in brain compared to males. However, significance of \(AMBRA1\) for autistic phenotypes in humans and, apart from behavior, for other autism-typical features, namely early brain enlargement or increased seizure propensity, has remained unexplored. Here we show in two independent human samples that a single normal \(AMBRA1\) genotype, the intronic SNP rs3802890-AA, is associated with autistic features in women, who also display lower \(AMBRA1\) mRNA expression in peripheral blood mononuclear cells relative to female GG carriers. Located within a non-coding RNA, likely relevant for mRNA and protein interaction, rs3802890 (A versus G allele) may affect its stability through modification of folding, as predicted by \(in\) \(silico\) analysis. Searching for further autism-relevant characteristics in \(Ambra1^{+/−}\) mice, we observe reduced interest of female but not male mutants regarding pheromone signals of the respective other gender in the social intellicage set-up. Moreover, altered pentylentetrazol-induced seizure propensity, an \(in\) \(vivo\) readout of neuronal excitation–inhibition dysbalance, becomes obvious exclusively in female mutants. Magnetic resonance imaging reveals mild prepubertal brain enlargement in both genders, uncoupling enhanced brain dimensions from the primarily female expression of all other autistic phenotypes investigated here. These data support a role of \(AMBRA1/Ambra1\) partial loss-of-function genotypes for female autistic traits. Moreover, they suggest \(Ambra1\) heterozygous mice as a novel multifaceted and construct-valid genetic mouse model for female autism.
KW  - biology
KW  - clinical genetics
KW  - molecular neuroscience
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-173782
VL  - 2017
IS  - 7
ER  -