Research Center for the Molecular Physiology of the Brain

Göttingen, Germany

Research Center for the Molecular Physiology of the Brain

Göttingen, Germany
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Doeppner T.R.,University of Goettingen Medical School | El Aanbouri M.,University of Goettingen Medical School | Dietz G.P.H.,Lundbeck | Dietz G.P.H.,Research Center for the Molecular Physiology of the Brain | And 4 more authors.
Neurobiology of Disease | Year: 2010

Neural precursor cells (NPC) are an interesting tool in experimental stroke research, but their therapeutic potential is limited due to poor long-term survival. We therefore in vitro transduced subventricular zone-(SVZ)-derived NPC with the anti-apoptotic fusion protein TAT-Bcl-xL and analyzed NPC survival, differentiation, and post-stroke functional deficits after experimental ischemia in mice. Survival of TAT-Bcl-xL-transduced NPC, which were injected at day 7 post-stroke into the ischemic striatum, was significantly increased at 4weeks after stroke. Increased survival of NPC was associated with reduced infarct injury and decreased post-stroke functional deficits. Animals grafted with TAT-Bcl-xL-transduced NPC showed an increased number of immature cells expressing the neuronal marker doublecortin. Since mature neuronal differentiation of NPC was not observed, reduced post-stroke injury cannot be attributed to enhanced neuronal regeneration, but rather to indirect by-stander effects of grafted NPC. In line with this, NPC-mediated neuroprotection of cortical neurons in vitro was associated with increased secretion of growth factors. Thus, in vitro transduction of cultivated NPC with TAT-Bcl-xL results in enhanced resistance of transplanted NPC followed by long-term neuroprotection and ameliorated functional deficits after transient focal cerebral ischemia in mice. © 2010 Elsevier Inc.

Doeppner T.R.,University of Goettingen Medical School | Dietz G.P.H.,Lundbeck | Dietz G.P.H.,Research Center for the Molecular Physiology of the Brain | Weise J.,University of Jena Medical School | And 2 more authors.
Experimental Neurology | Year: 2010

Endogenous neurogenesis persists in the subgranular zone (SGZ) of the adult rodent brain. Cerebral ischemia stimulates endogenous neurogenesis involving proliferation, migration and differentiation of SGZ-derived neural precursor cells (NPC). However, the biological meaning of this phenomenon is limited by poor survival of NPC. In order to study the effects of an acute neuroprotective treatment on hippocampal endogenous neurogenesis after transient cerebral ischemia in mice, we applied a fusion protein consisting of the TAT domain of the HI virus with the anti-apoptotic Bcl-xL. Intravenous injection of TAT-Bcl-xL resulted in reduced hippocampal cell injury for up to 4weeks after stroke as assessed by TUNEL and NeuN staining. This was in line with a TAT-Bcl-xL-mediated reduced postischemic microglia activation. Analysis of endogenous hippocampal cell proliferation revealed an increased number of BrdU+ cells in the TAT-Bcl-xL group 4weeks after stroke compared to animals treated with saline and TAT-HA (negative control). Cell proliferation in non-ischemic sham operated animals was not affected by TAT-Bcl-xL. Twenty-eight days after stroke co-expression of BrdU+ cells with the immature neuronal marker doublecortin was significantly increased in TAT-Bcl-xL animals. Although TAT-Bcl-xL treatment also resulted in an increased number of BrdU+ cells expressing the mature neuronal marker NeuN, the total amount of these cells was low. These data show that TAT-Bcl-xL treatment yields both postischemic sustained hippocampal neuroprotection and increased survival of NPC rather than an induction of endogenous neurogenesis itself. © 2010 Elsevier Inc.

Rosenthal E.H.,Max Planck Institute for Biophysical Chemistry | Rosenthal E.H.,University of Southern Denmark | Tonchev A.B.,Max Planck Institute for Biophysical Chemistry | Tonchev A.B.,Molecular Developmental Neurobiology Laboratory | And 5 more authors.
Hippocampus | Year: 2012

The molecular mechanisms of regionalization of the medial pallium (MP), the anlage of the hippocampus, and transitional (cingulate and retrosplenial) cortices are largely unknown. Previous analyses have outlined an important role of the transcription factor (TF) Zbtb20 for hippocampal CA1 field specification (Nielsen et al. (2007) Development 134:1133-1140; Nielsen et al. (2010) Cereb Cortex 20:1904-1914; Xie et al. (2010) Proc Natl Acad Sci USA 107:6510-6515). Here, we present novel data showing that Zbtb20 exhibits a ventralhigh-to-dorsallow gradient of expression in MP progenitors as well as an expression in postmitotic cells at the transitional cortex/neocortex border. Our detailed pattern analysis revealed that in Zbtb20 loss-of-function the molecular borders between neocortical, transitional, and hippocampal fields are progressively shifted ventrally, leading to an ectopic positioning of all dorsal fields into the neighboring ventrally located areas. Thus, in addition to its known importance for the specification of the hippocampal CA1 sector, the graded expression of TF Zbtb20 in ventricular zone of MP appears to translate early positional information for establishment of all developing MP fields. Our data also suggest that the signaling factor Wnt3a is a putative molecular partner of TF Zbtb20 in this patterning process. © 2012 Wiley Periodicals, Inc.

Doeppner T.R.,University of Duisburg - Essen | Doeppner T.R.,University of Gottingen | Doehring M.,University of Gottingen | Bretschneider E.,University of Gottingen | And 8 more authors.
Acta Neuropathologica | Year: 2013

MicroRNAs (miRNAs) are highly conserved non-coding RNAs modulating gene expression via mRNA binding. Recent work suggests an involvement of miRNAs in cardiovascular diseases including stroke. As such, the brain-abundant miR-124 and its transcriptional repressor RE1-silencing transcription factor (REST) do not only have elementary roles in the developing and the adult brain, but also alter expression upon cerebral ischemia. However, the therapeutic potential of miR-124 against stroke and the mechanisms involved remain elusive. Here, we analyzed the therapeutic potential of ectopic miR-124 against stroke and its underlying mechanisms with regard to the interaction between miR-124 and REST. Our results show that viral vector-mediated miR-124 delivery increased the resistance of cultured oxygen-glucose-deprived cortical neurons in vitro and reduced brain injury as well as functional impairment in mice submitted to middle cerebral artery occlusion. Likewise, miR-124 induced enhanced neurovascular remodeling leading to increased angioneurogenesis 8 weeks post-stroke. While REST abundance increased upon stroke, the increase was prevented by miR-124 despite a so far unknown negative feedback loop between miR-124 and REST. Rather, miR-124 decreased the expression of the deubiquitinating enzyme Usp14, which has two conserved miR-124-binding sites in the 3′UTR of its mRNA, and thereby mediated reduced REST levels. The down-regulation of REST by miR-124 was also mimicked by the Usp14 inhibitor IU-1, suggesting that miR-124 promotes neuronal survival under ischemic conditions via Usp14-dependent REST degradation. Ectopic miR-124 expression, therefore, appears as an attractive and novel tool in stroke treatment, mediating neuroprotection via a hitherto unknown mechanism that involves Usp14-dependent REST degradation. © 2013 Springer-Verlag Berlin Heidelberg.

Rezaei-Ghaleh N.,Max Planck Institute for Biophysical Chemistry | Andreetto E.,TU Munich | Yan L.-M.,TU Munich | Kapurniotu A.,TU Munich | And 2 more authors.
PLoS ONE | Year: 2011

Assembly of amyloid-beta peptide (Aβ) into cytotoxic oligomeric and fibrillar aggregates is believed to be a major pathologic event in Alzheimer's disease (AD) and interfering with Aβ aggregation is an important strategy in the development of novel therapeutic approaches. Prior studies have shown that the double N-methylated analogue of islet amyloid polypeptide (IAPP) IAPP-GI, which is a conformationally constrained IAPP analogue mimicking a non-amyloidogenic IAPP conformation, is capable of blocking cytotoxic self-assembly of Aβ. Here we investigate the interaction of IAPP-GI with Aβ40 and Aβ42 using NMR spectroscopy. The most pronounced NMR chemical shift changes were observed for residues 13-20, while residues 7-9, 15-16 as well as the C-terminal half of Aβ - that is both regions of the Aβ sequence that are converted into β-strands in amyloid fibrils - were less accessible to solvent in the presence of IAPP-GI. At the same time, interaction of IAPP-GI with Aβ resulted in a concentration-dependent co-aggregation of Aβ and IAPP-GI that was enhanced for the more aggregation prone Aβ42 peptide. On the basis of the reduced toxicity of the Aβ peptide in the presence of IAPP-GI, our data are consistent with the suggestion that IAPP-GI redirects Aβ into nontoxic "off-pathway" aggregates. © 2011 Rezaei-Ghaleh et al.

Woehler A.,Research Center for the Molecular Physiology of the Brain | Woehler A.,Max Planck Institute for Biophysical Chemistry | Woehler A.,University of Gottingen | Wlodarczyk J.,Nencki Institute of Experimental Biology | And 2 more authors.
Biophysical Journal | Year: 2010

Molecular sensors based on intramolecular Förster resonance energy transfer (FRET) have become versatile tools to monitor regulatory molecules in living tissue. However, their use is often compromised by low signal strength and excessive noise. We analyzed signal/noise (SNR) aspects of spectral FRET analysis methods, with the following conclusions: The most commonly used method (measurement of the emission ratio after a single short wavelength excitation) is optimal in terms of signal/noise, if only relative changes of this uncalibrated ratio are of interest. In the case that quantitative data on FRET efficiencies are required, these can be calculated from the emission ratio and some calibration parameters, but at reduced SNR. Lux-FRET, a recently described method for spectral analysis of FRET data, allows one to do so in three different ways, each based on a ratio of two out of three measured fluorescence signals (the donor and acceptor signal during a short-wavelength excitation and the acceptor signal during long wavelength excitation). Lux-FRET also allows for calculation of the total abundance of donor and acceptor fluorophores. The SNR for all these quantities is lower than that of the plain emission ratio due to unfavorable error propagation. However, if ligand concentration is calculated either from lux-FRET values or else, after its calibration, from the emission ratio, SNR for both analysis modes is very similar. Likewise, SNR values are similar, if the noise of these quantities is related to the expected dynamic range. We demonstrate these relationships based on data from an Epac-based cAMP sensor and discuss how the SNR changes with the FRET efficiency and the number of photons collected. © 2010 by the Biophysical Society.

Cho M.-K.,Max Planck Institute for Biophysical Chemistry | Kim H.-Y.,Max Planck Institute for Biophysical Chemistry | Fernandez C.O.,National University of Rosario | Becker S.,Max Planck Institute for Biophysical Chemistry | And 2 more authors.
Protein Science | Year: 2011

The major component of neural inclusions that are the pathological hallmark of Parkinson's disease are amyloid fibrils of the protein α-synuclein (aS). Here we investigated if the disease-related mutation A30P not only modulates the kinetics of aS aggregation, but also alters the structure of amyloid fibrils. To this end we optimized the method of quenched hydrogen/deuterium exchange coupled to NMR spectroscopy and performed two-dimensional proton-detected highresolution magic angle spinning experiments. The combined data indicate that the A30P mutation does not cause changes in the number, location and overall arrangement of β-strands in amyloid fibrils of aS. At the same time, several residues within the fibrillar core retain nano-second dynamics. We conclude that the increased pathogenicity related to the familial A30P mutation is unlikely to be caused by a mutation-induced change in the conformation of aS aggregates. Published by Wiley-Blackwell. © 2010 The Protein Society.

Doeppner T.R.,University of Duisburg - Essen | Kaltwasser B.,University of Duisburg - Essen | Elali A.,University of Duisburg - Essen | Zechariah A.,University of Duisburg - Essen | And 3 more authors.
Journal of Cerebral Blood Flow and Metabolism | Year: 2011

Hepatocyte growth factor (HGF) is an interesting candidate for acute stroke treatment as shown by continuous infusion or gene delivery protocols. However, little is known about HGF-mediated long-term effects. The present study therefore analyzed long-term effects of an acute intrastriatal HGF treatment (5 g) after a 45-minute stroke, with regard to brain injury and neurologic recovery. Hepatocyte growth factor induced long-term neuroprotection as assessed by infarct volume and neuronal cell death analysis for as long as 4 weeks after stroke, which was associated with sustained neurologic recovery as evidenced by corner-turn and tight-rope tests. Analyzing underlying mechanisms of HGF-induced sustained neuroprotection, enhanced cell proliferation followed by increased neuronal differentiation of neural precursor cells (NPCs) was observed in the ischemic striatum of HGF-treated mice, which persisted for up to 4 weeks. In line with this, HGF promoted neurosphere formation as well as proliferation of NPC and decreased caspase-3-dependent hypoxic injury in vitro. Preservation of blood-brain barrier integrity 24 hours after stroke was furthermore noticed in animals receiving HGF, which was associated with the inhibition of matrix metalloproteases (MMP)-2 and MMP-9 at 4 and 24 hours, respectively. We suggest that sustained recruitment of proliferating cells together with improved neurovascular remodeling provides an explanation for HGF-induced long-term neuroprotection. © 2011 ISCBFM All rights reserved.

Kumar S.,University of Bonn | Rezaei-Ghaleh N.,Max Planck Institute for Biophysical Chemistry | Terwel D.,University of Bonn | Thal D.R.,University of Ulm | And 10 more authors.
EMBO Journal | Year: 2011

Alzheimer's disease (AD) is the most common form of dementia and associated with progressive deposition of amyloid β 2-peptides (Aβ 2) in the brain. Aβ 2 derives by sequential proteolytic processing of the amyloid precursor protein by β 2-and β 3-secretases. Rare mutations that lead to amino-acid substitutions within or close to the Aβ 2 domain promote the formation of neurotoxic Aβ 2 assemblies and can cause early-onset AD. However, mechanisms that increase the aggregation of wild-type Aβ 2 and cause the much more common sporadic forms of AD are largely unknown. Here, we show that extracellular Aβ 2 undergoes phosphorylation by protein kinases at the cell surface and in cerebrospinal fluid of the human brain. Phosphorylation of serine residue 8 promotes formation of oligomeric Aβ 2 assemblies that represent nuclei for fibrillization. Phosphorylated Aβ 2 was detected in the brains of transgenic mice and human AD brains and showed increased toxicity in Drosophila models as compared with non-phosphorylated Aβ 2. Phosphorylation of Aβ 2 could represent an important molecular mechanism in the pathogenesis of the most common sporadic form of AD. © 2011 European Molecular Biology Organization.

Binolfi A.,National University of Rosario | Valiente-Gabioud A.A.,National University of Rosario | Duran R.,Institute Pasteur Of Montevideo Ipm | Duran R.,Institute Investigaciones Biologicas Clemente Estable IIBCE | And 5 more authors.
Journal of the American Chemical Society | Year: 2011

The aggregation of α-synuclein (AS) is selectively enhanced by copper in vitro, and the interaction is proposed to play a potential role in vivo. In this work, we report the structural, residue-specific characterization of Cu(I) binding to AS and demonstrate that the protein is able to bind Cu(I) with relatively high affinity in a coordination environment that involves the participation of Met1 and Met5 residues. This knowledge is a key to understanding the structural-aggregation basis of the copper-catalyzed oxidation of AS. © 2010 American Chemical Society.

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