FMP Publications

Our publications are recorded in a searchable database since 2010, updates will be added regularly.

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References
High resolution observed in 800 MHz DNP spectra of extremely rigid type III secretion needles
Fricke, P., Mance(*), D., Chevelkov, V., Giller(*), K., Becker(*), S., Baldus(*), M.; Lange, A.
J Biomol NMR, 65:121-126
(2016)

Tags: Molecular Biophysics (Lange, A.)

Abstract: The cryogenic temperatures at which dynamic nuclear polarization (DNP) solid-state NMR experiments need to be carried out cause line-broadening, an effect that is especially detrimental for crowded protein spectra. By increasing the magnetic field strength from 600 to 800 MHz, the resolution of DNP spectra of type III secretion needles (T3SS) could be improved by 22 %, indicating that inhomogeneous broadening is not the dominant effect that limits the resolution of T3SS needles under DNP conditions. The outstanding spectral resolution of this system under DNP conditions can be attributed to its low overall flexibility.

Tubular Epithelial NF-kappaB Activity Regulates Ischemic AKI
Marko(*), L., Vigolo(*), E., Hinze(*), C., Park(*), J. K., Roel(*), G., Balogh(*), A., Choi(*), M., Wübken(*), A., Cording, J., Blasig, I. E., Luft(*), F. C., Scheidereit(*), C., Schmidt-Ott(*), K. M., Schmidt-Ullrich(*), R.; Müller(*), D. N.
Journal of the American Society of Nephrology : JASN, 27:2658-2669
(2016)

Tags: Molecular Cell Physiology (Blasig, I.E.)

Abstract: NF-kappaB is a key regulator of innate and adaptive immunity and is implicated in the pathogenesis of AKI. The cell type-specific functions of NF-kappaB in the kidney are unknown; however, the pathway serves distinct functions in immune and tissue parenchymal cells. We analyzed tubular epithelial-specific NF-kappaB signaling in a mouse model of ischemia-reperfusion injury (IRI)-induced AKI. NF-kappaB reporter activity and nuclear localization of phosphorylated NF-kappaB subunit p65 analyses in mice revealed that IRI induced widespread NF-kappaB activation in renal tubular epithelia and in interstitial cells that peaked 2-3 days after injury. To genetically antagonize tubular epithelial NF-kappaB activity, we generated mice expressing the human NF-kappaB super-repressor IkappaBalphaDeltaN in renal proximal, distal, and collecting duct epithelial cells. Compared with control mice, these mice exhibited improved renal function, reduced tubular apoptosis, and attenuated neutrophil and macrophage infiltration after IRI-induced AKI. Furthermore, tubular NF-kappaB-dependent gene expression profiles revealed temporally distinct functional gene clusters for apoptosis, chemotaxis, and morphogenesis. Primary proximal tubular cells isolated from IkappaBalphaDeltaN-expressing mice and exposed to hypoxia-mimetic agent cobalt chloride exhibited less apoptosis and expressed lower levels of chemokines than cells from control mice did. Our results indicate that postischemic NF-kappaB activation in renal tubular epithelia aggravates tubular injury and exacerbates a maladaptive inflammatory response.

5-Aryl-2-(naphtha-1-yl)sulfonamido-thiazol-4(5H)-ones as clathrin inhibitors
Robertson(*), M. J., Horatscheck, A., Sauer, S., von Kleist(*), L., Baker, J. R., Stahlschmidt, W., Nazare, M., Whiting(*), A., Chau(*), N., Robinson(*), P. J., Haucke, V.; McCluskey(*), A.
Org Biomol Chem, 14:11266-11278
(2016)

Tags: Molecular Pharmacology and Cell Biology (Haucke), Medicinal Chemistry (Nazare)

Abstract: The development of a (Z)-5-((6,8-dichloro-4-oxo-4H-chromen-3-yl)methylene)-2-thioxothiazolidin-4-one (2), rhodanine-based lead that led to the Pitstop(R) 2 family of clathrin inhibitors is described herein. Head group substitution and bioisosteric replacement of the rhodanine core with a 2-aminothiazol-4(5H)-one scaffold eliminated off target dynamin activity. A series of N-substituents gave first phenylglycine (20, IC50 approximately 20 muM) then phenyl (25, IC50 approximately 7.1 muM) and 1-napthyl sulfonamide (26, Pitstop(R) 2 compound, IC50 approximately 1.9 muM) analogues with good activity, validating this approach. A final library exploring the head group resulted in three analogues displaying either slight improvements or comparable activity (33, 38, and 29 with IC50 approximately 1.4, 1.6 and 1.8 muM respectively) and nine others with IC50 < 10 muM. These results were rationalized using in silico docking studies. Docking studies predicted enhanced Pitstop(R) 2 family binding, not a loss of binding, within the Pistop(R) groove of the reported clathrin mutant invalidating recent assumptions of poor selectivity for this family of clathrin inhibitors.

Dynamics of the Ligand Binding Domain Layer during AMPA Receptor Activation
Baranovic, J., Chebli, M., Salazar, H., Carbone, A. L., Faelber(*), K., Lau(*), A. Y., Daumke(*), O.; Plested, A. J.
Biophys J, 110:896-911
(2016)

Tags: Molecular Neuroscience and Biophysics (Plested)

Abstract: Ionotropic glutamate receptors are postsynaptic tetrameric ligand-gated channels whose activity mediates fast excitatory transmission. Glutamate binding to clamshell-shaped ligand binding domains (LBDs) triggers opening of the integral ion channel, but how the four LBDs orchestrate receptor activation is unknown. Here, we present a high-resolution x-ray crystal structure displaying two tetrameric LBD arrangements fully bound to glutamate. Using a series of engineered metal ion trapping mutants, we showed that the more compact of the two assemblies corresponds to an arrangement populated during activation of full-length receptors. State-dependent cross-linking of the mutants identified zinc bridges between the canonical active LBD dimers that formed when the tetramer was either fully or partially bound by glutamate. These bridges also stabilized the resting state, consistent with the recently published full-length apo structure. Our results provide insight into the activation mechanism of glutamate receptors and the complex conformational space that the LBD layer can sample.

Superactivation of AMPA receptors by auxiliary proteins
Carbone, A. L.; Plested, A. J.
Nat Commun, 7:10178
(2016)

Tags: Molecular Neuroscience and Biophysics (Plested)

Abstract: Glutamate receptors form complexes in the brain with auxiliary proteins, which control their activity during fast synaptic transmission through a seemingly bewildering array of effects. Here we devise a way to isolate the activation of complexes using polyamines, which enables us to show that transmembrane AMPA receptor regulatory proteins (TARPs) exert their effects principally on the channel opening reaction. A thermodynamic argument suggests that because TARPs promote channel opening, receptor activation promotes AMPAR-TARP complexes into a superactive state with high open probability. A simple model based on this idea predicts all known effects of TARPs on AMPA receptor function. This model also predicts unexpected phenomena including massive potentiation in the absence of desensitization and supramaximal recovery that we subsequently detected in electrophysiological recordings. This transient positive feedback mechanism has implications for information processing in the brain, because it should allow activity-dependent facilitation of excitatory synaptic transmission through a postsynaptic mechanism.

Young, active and well-connected: adult-born neurons in the zebra finch are activated during singing
Tokarev(*), K., Boender(*), A. J., Classen, G. A.; Scharff(*), C.
Brain Struct Funct, 221:1833-1843
(2016)

Tags: Molecular Pharmacology and Cell Biology (Haucke)

Abstract: Neuronal replacement in the pallial song control nucleus HVC of adult zebra finches constitutes an interesting case of homeostatic plasticity; in spite of continuous addition and attrition of neurons in ensembles that code song elements, adult song remains remarkably invariant. New neurons migrate into HVC and later synapse with their target, arcopallial song nucleus RA (HVCRA). New HVCRA neurons respond to auditory stimuli (in anaesthetised animals), but whether and when they become functionally active during singing is unknown. We studied this, using 5-bromo-2'-deoxyuridine to birth-date neurons, combined with immunohistochemical detection of immediate-early gene (IEG) expression and retrograde tracer injections into RA to track connectivity. Interestingly, singing was followed by IEG expression in a substantial fraction of new neurons that were not retrogradely labelled from RA, suggesting a possible role in HVC-intrinsic network function. As new HVC neurons matured, the proportion of HVCRA neurons that expressed IEGs after singing increased significantly. Since it was previously shown that singing induces IEG expression in HVC also in deaf birds and that hearing song does not induce IEG expression in HVC, our data provide the first direct evidence that new HVC neurons are engaged in song motor behaviour.

Hypothalamic feedforward inhibition of thalamocortical network controls arousal and consciousness
Herrera(*), C. G., Cadavieco, M. C., Jego(*), S., Ponomarenko, A., Korotkova, T.; Adamantidis(*), A.
Nat Neurosci, 19:290-298
(2016)

Tags: Behavioral Neurodynamics (Korotkova/Ponomarenko)

Abstract: During non-rapid eye movement (NREM) sleep, synchronous synaptic activity in the thalamocortical network generates predominantly low-frequency oscillations (<4 Hz) that are modulated by inhibitory inputs from the thalamic reticular nucleus (TRN). Whether TRN cells integrate sleep-wake signals from subcortical circuits remains unclear. We found that GABA neurons from the lateral hypothalamus (LHGABA) exert a strong inhibitory control over TRN GABA neurons (TRNGABA). We found that optogenetic activation of this circuit recapitulated state-dependent changes of TRN neuron activity in behaving mice and induced rapid arousal during NREM, but not REM, sleep. During deep anesthesia, activation of this circuit induced sustained cortical arousal. In contrast, optogenetic silencing of LHGABA-TRNGABA transmission increased the duration of NREM sleep and amplitude of delta (1-4 Hz) oscillations. Collectively, these results demonstrate that TRN cells integrate subcortical arousal inputs selectively during NREM sleep and may participate in sleep intensity.

Organophosphorus-mediated N-N bond formation: facile access to 3-amino-2H-indazoles
Bel Abed, H., Schöne, J., Christmann(*), M.; Nazare, M.
Org Biomol Chem, 14:8520-8528
(2016)

Tags: Medicinal Chemistry (Nazare)

Abstract: A convenient and efficient strategy has been devised to access 3-amino-2H-indazole derivatives in two steps from readily available starting materials. The conversion of 2-nitrobenzonitriles to substituted benzamidines followed by an organophosphorus-mediated reductive cyclization and a subsequent N-N bond formation afforded 3-amino-2H-indazoles in good to excellent yields.

Automatic (1)H-NMR Screening of Fatty Acid Composition in Edible Oils
Castejon(*), D., Fricke, P., Cambero(*), M. I.; Herrera(*), A.
Nutrients, 8:93
(2016)

Tags: Molecular Biophysics (Lange, A.)

Abstract: In this work, we introduce an NMR-based screening method for the fatty acid composition analysis of edible oils. We describe the evaluation and optimization needed for the automated analysis of vegetable oils by low-field NMR to obtain the fatty acid composition (FAC). To achieve this, two scripts, which automatically analyze and interpret the spectral data, were developed. The objective of this work was to drive forward the automated analysis of the FAC by NMR. Due to the fact that this protocol can be carried out at low field and that the complete process from sample preparation to printing the report only takes about 3 min, this approach is promising to become a fundamental technique for high-throughput screening. To demonstrate the applicability of this method, the fatty acid composition of extra virgin olive oils from various Spanish olive varieties (arbequina, cornicabra, hojiblanca, manzanilla, and picual) was determined by (1)H-NMR spectroscopy according to this protocol.

Occludin controls HIV transcription in brain pericytes via regulation of SIRT-1 activation
Castro(*), V., Bertrand(*), L., Luethen(*), M., Dabrowski, S., Lombardi(*), J., Morgan(*), L., Sharova(*), N., Stevenson(*), M., Blasig, I. E.; Toborek(*), M.
FASEB J, 30:1234-1246
(2016)

Tags: Molecular Cell Physiology (Blasig, I.E.)

Abstract: HIV invades the brain early after infection; however, its interactions with the cells of the blood-brain barrier (BBB) remain poorly understood. Our goal was to evaluate the role of occludin, one of the tight junction proteins that regulate BBB functions in HIV infection of BBB pericytes. We provide evidence that occludin levels largely control the metabolic responses of human pericytes to HIV. Occludin in BBB pericytes decreased by 10% during the first 48 h after HIV infection, correlating with increased nuclear translocation of the gene repressor C-terminal-binding protein (CtBP)-1 and NFkappaB-p65 activation. These changes were associated with decreased expression and activation of the class III histone deacetylase sirtuin (SIRT)-1. Occludin levels recovered 96 h after infection, restoring SIRT-1 and reducing HIV transcription to 20% of its highest values. We characterized occludin biochemically as a novel NADH oxidase that controls the expression and activation of SIRT-1. The inverse correlation between occludin and HIV transcription was then replicated in human primary macrophages and differentiated monocytic U937 cells, in which occludin silencing resulted in 75 and 250% increased viral transcription, respectively. Our work shows that occludin has previously unsuspected metabolic properties and is a target of HIV infection, opening the possibility of designing novel pharmacological approaches to control HIV transcription.

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