FMP Publications

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

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References
Type II PI4-kinases control Weibel-Palade body biogenesis and von Willebrand factor structure in human endothelial cells
Lopes da Silva(*), M., O'Connor(*), M. N., Kriston-Vizi(*), J., White(*), I. J., Al-Shawi(*), R., Simons(*), J. P., Mössinger, J., Haucke, V.; Cutler(*), D. F.
J Cell Sci, 129:2096-2105
(2016)

Tags: Molecular Pharmacology and Cell Biology (Haucke)

Abstract: Weibel-Palade bodies (WPBs) are endothelial storage organelles that mediate the release of molecules involved in thrombosis, inflammation and angiogenesis, including the pro-thrombotic glycoprotein von Willebrand factor (VWF). Although many protein components required for WPB formation and function have been identified, the role of lipids is almost unknown. We examined two key phosphatidylinositol kinases that control phosphatidylinositol 4-phosphate levels at the trans-Golgi network, the site of WPB biogenesis. RNA interference of the type II phosphatidylinositol 4-kinases PI4KIIalpha and PI4KIIbeta in primary human endothelial cells leads to formation of an increased proportion of short WPB with perturbed packing of VWF, as exemplified by increased exposure of antibody-binding sites. When stimulated with histamine, these cells release normal levels of VWF yet, under flow, form very few platelet-catching VWF strings. In PI4KIIalpha-deficient mice, immuno-microscopy revealed that VWF packaging is also perturbed and these mice exhibit increased blood loss after tail cut compared to controls. This is the first demonstration that lipid kinases can control the biosynthesis of VWF and the formation of WPBs that are capable of full haemostatic function.

Active zone scaffolds differentially accumulate Unc13 isoforms to tune Ca(2+) channel-vesicle coupling
Böhme(*), M. A., Beis(*), C., Reddy-Alla(*), S., Reynolds(*), E., Mampell(*), M. M., Grasskamp, A. T., Lutzkendorf(*), J., Bergeron(*), D. D., Driller(*), J. H., Babikir(*), H., Göttfert(*), F., Robinson(*), I. M., O'Kane(*), C. J., Hell(*), S. W., Wahl(*), M. C., Stelzl(*), U., Loll(*), B., Walter, A. M.; Sigrist(*), S. J.
Nat Neurosci, 19:1311-1320
(2016)

Tags: Molecular and Theoretical Neuroscience (Walter)

Abstract: Brain function relies on fast and precisely timed synaptic vesicle (SV) release at active zones (AZs). Efficacy of SV release depends on distance from SV to Ca(2+) channel, but molecular mechanisms controlling this are unknown. Here we found that distances can be defined by targeting two unc-13 (Unc13) isoforms to presynaptic AZ subdomains. Super-resolution and intravital imaging of developing Drosophila melanogaster glutamatergic synapses revealed that the Unc13B isoform was recruited to nascent AZs by the scaffolding proteins Syd-1 and Liprin-alpha, and Unc13A was positioned by Bruchpilot and Rim-binding protein complexes at maturing AZs. Unc13B localized 120 nm away from Ca(2+) channels, whereas Unc13A localized only 70 nm away and was responsible for docking SVs at this distance. Unc13A(null) mutants suffered from inefficient, delayed and EGTA-supersensitive release. Mathematical modeling suggested that synapses normally operate via two independent release pathways differentially positioned by either isoform. We identified isoform-specific Unc13-AZ scaffold interactions regulating SV-Ca(2+)-channel topology whose developmental tightening optimizes synaptic transmission.

Chemical tools for interrogating inositol pyrophosphate structure and function
Brown, N. W., Marmelstein, A. M.; Fiedler, D.
Chem Soc Rev, 45:6311-6326
(2016)

Tags: Chemical Biology I (Fiedler)

Abstract: The inositol pyrophosphates (PP-InsPs) are a unique group of intracellular messengers that represent some of the most highly phosphorylated molecules in nature. Genetic perturbation of the PP-InsP biosynthetic network indicates a central role for these metabolites in maintaining cellular energy homeostasis and in controlling signal transduction networks. However, despite their discovery over two decades ago, elucidating their physiologically relevant isomers, the biochemical pathways connecting these molecules to their associated phenotypes, and their modes of signal transduction has often been stymied by technical challenges. Many of the advances in understanding these molecules to date have been facilitated by the total synthesis of the various PP-InsP isomers and by the development of new methods that are capable of identifying their downstream signalling partners. Chemical tools have also been developed to distinguish between the proposed PP-InsP signal transduction mechanisms: protein binding, and a covalent modification of proteins termed protein pyrophosphorylation. In this article, we review these recent developments, discuss how they have helped to illuminate PP-InsP structure and function, and highlight opportunities for future discovery.

C-type natriuretic peptide and natriuretic peptide receptor B signalling inhibits cardiac sympathetic neurotransmission and autonomic function
Buttgereit(*), J., Shanks(*), J., Li(*), D., Hao(*), G., Athwal(*), A., Langenickel(*), T. H., Wright(*), H., da Costa Goncalves, A. C., Monti(*), J., Plehm(*), R., Popova(*), E., Qadri(*), F., Lapidus(*), I., Ryan(*), B., Ozcelik(*), C., Paterson(*), D. J., Bader(*), M.; Herring(*), N.
Cardiovasc Res, 112:637-644
(2016)

Tags: Anchored Signaling (Klussmann)

Abstract: AIMS: B-type natriuretic peptide (BNP)-natriuretic peptide receptor A (NPR-A) receptor signalling inhibits cardiac sympathetic neurotransmission, although C-type natriuretic peptide (CNP) is the predominant neuropeptide of the nervous system with expression in the heart and vasculature. We hypothesized that CNP acts similarly to BNP, and that transgenic rats (TGRs) with neuron-specific overexpression of a dominant negative NPR-B receptor would develop heightened sympathetic drive. METHODS AND RESULTS: Mean arterial pressure and heart rate (HR) were significantly (P < 0.05) elevated in freely moving TGRs (n = 9) compared with Sprague Dawley (SD) controls (n = 10). TGR had impaired left ventricular systolic function and spectral analysis of HR variability suggested a shift towards sympathoexcitation. Immunohistochemistry demonstrated co-staining of NPR-B with tyrosine hydroxylase in stellate ganglia neurons. In SD rats, CNP (250 nM, n = 8) significantly reduced the tachycardia during right stellate ganglion stimulation (1-7 Hz) in vitro whereas the response to bath-applied norepinephrine (NE, 1 muM, n = 6) remained intact. CNP (250 nM, n = 8) significantly reduced the release of 3H-NE in isolated atria and this was prevented by the NPR-B antagonist P19 (250 nM, n = 6). The neuronal Ca2+ current (n = 6) and intracellular Ca2+ transient (n = 9, using fura-2AM) were also reduced by CNP in isolated stellate neurons. Treatment of the TGR (n = 9) with the sympatholytic clonidine (125 microg/kg per day) significantly reduced mean arterial pressure and HR to levels observed in the SD (n = 9). CONCLUSION: C-type natriuretic peptide reduces cardiac sympathetic neurotransmission via a reduction in neuronal calcium signalling and NE release through the NPR-B receptor. Situations impairing CNP-NPR-B signalling lead to hypertension, tachycardia, and impaired left ventricular systolic function secondary to sympatho-excitation.

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.

Structural basis for the dissociation of alpha-synuclein fibrils triggered by pressure perturbation of the hydrophobic core
de Oliveira(*), G. A., Marques(*), M. A., Cruzeiro-Silva(*), C., Cordeiro(*), Y., Schuabb(*), C., Moraes(*), A. H., Winter(*), R., Oschkinat, H., Foguel(*), D., Freitas(*), M. S.; Silva(*), J. L.
Sci Rep, 6:37990
(2016)

Tags: NMR-Supported Structural Biology (Oschkinat)

Abstract: Parkinson's disease is a neurological disease in which aggregated forms of the alpha-synuclein (alpha-syn) protein are found. We used high hydrostatic pressure (HHP) coupled with NMR spectroscopy to study the dissociation of alpha-syn fibril into monomers and evaluate their structural and dynamic properties. Different dynamic properties in the non-amyloid-beta component (NAC), which constitutes the Greek-key hydrophobic core, and in the acidic C-terminal region of the protein were identified by HHP NMR spectroscopy. In addition, solid-state NMR revealed subtle differences in the HHP-disturbed fibril core, providing clues to how these species contribute to seeding alpha-syn aggregation. These findings show how pressure can populate so far undetected alpha-syn species, and they lay out a roadmap for fibril dissociation via pathways not previously observed using other approaches. Pressure perturbs the cavity-prone hydrophobic core of the fibrils by pushing water inward, thereby inducing the dissociation into monomers. Our study offers the molecular details of how hydrophobic interaction and the formation of water-excluded cavities jointly contribute to the assembly and stabilization of the fibrils. Understanding the molecular forces behind the formation of pathogenic fibrils uncovered by pressure perturbation will aid in the development of new therapeutics against Parkinson's disease.

Bimodal antagonism of PKA signalling by ARHGAP36
Eccles(*), R. L., Czajkowski(*), M. T., Barth(*), C., Müller(*), P. M., McShane(*), E., Grunwald(*), S., Beaudette(*), P., Mecklenburg(*), N., Volkmer, R., Zühlke(*), K., Dittmar(*), G., Selbach(*), M., Hammes(*), A., Daumke(*), O., Klussmann(*), E., Urbe(*), S.; Rocks(*), O.
Nat Commun, 7:12963
(2016)

Tags: Peptide Synthesis (Hackenberger/Volkmer)

Abstract: Protein kinase A is a key mediator of cAMP signalling downstream of G-protein-coupled receptors, a signalling pathway conserved in all eukaryotes. cAMP binding to the regulatory subunits (PKAR) relieves their inhibition of the catalytic subunits (PKAC). Here we report that ARHGAP36 combines two distinct inhibitory mechanisms to antagonise PKA signalling. First, it blocks PKAC activity via a pseudosubstrate motif, akin to the mechanism employed by the protein kinase inhibitor proteins. Second, it targets PKAC for rapid ubiquitin-mediated lysosomal degradation, a pathway usually reserved for transmembrane receptors. ARHGAP36 thus dampens the sensitivity of cells to cAMP. We show that PKA inhibition by ARHGAP36 promotes derepression of the Hedgehog signalling pathway, thereby providing a simple rationale for the upregulation of ARHGAP36 in medulloblastoma. Our work reveals a new layer of PKA regulation that may play an important role in development and disease.

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.

Temperature dependence of cross-effect dynamic nuclear polarization in rotating solids: advantages of elevated temperatures
Geiger, M. A., Orwick-Rydmark, M., Marker, K., Franks, W. T., Akhmetzyanov(*), D., Stöppler, D., Zinke, M., Specker, E., Nazare, M., Diehl, A., van Rossum, B. J., Aussenac(*), F., Prisner(*), T., Akbey, Ü.; Oschkinat, H.
Phys Chem Chem Phys, 18:30696-30704
(2016)

Tags: NMR-Supported Structural Biology (Oschkinat), Medicinal Chemistry (Nazare), Molecular Biophysics (Lange, A.)

Abstract: Dynamic nuclear polarization exploits electron spin polarization to boost signal-to-noise in magic-angle-spinning (MAS) NMR, creating new opportunities in materials science, structural biology, and metabolomics studies. Since protein NMR spectra recorded under DNP conditions can show improved spectral resolution at 180-200 K compared to 110 K, we investigate the effects of AMUPol and various deuterated TOTAPOL isotopologues on sensitivity and spectral resolution at these temperatures, using proline and reproducibly prepared SH3 domain samples. The TOTAPOL deuteration pattern is optimized for protein DNP MAS NMR, and signal-to-noise per unit time measurements demonstrate the high value of TOTAPOL isotopologues for Protein DNP MAS NMR at 180-200 K. The combined effects of enhancement, depolarization, and proton longitudinal relaxation are surprisingly sample-specific. At 200 K, DNP on SH3 domain standard samples yields a 15-fold increase in signal-to-noise over a sample without radicals. 2D and 3D NCACX/NCOCX spectra were recorded at 200 K within 1 and 13 hours, respectively. Decreasing enhancements with increasing 2H-content at the CH2 sites of the TEMPO rings in CD3-TOTAPOL highlight the importance of protons in a sphere of 4-6 A around the nitroxyl group, presumably for polarization pickup from electron spins.

RIM-binding protein 2 regulates release probability by fine-tuning calcium channel localization at murine hippocampal synapses
Grauel(*), M. K., Maglione, M., Reddy-Alla(*), S., Willmes(*), C. G., Brockmann(*), M. M., Trimbuch(*), T., Rosenmund(*), T., Pangalos(*), M., Vardar(*), G., Stumpf(*), A., Walter, A. M., Rost(*), B. R., Eickholt(*), B. J., Haucke, V., Schmitz(*), D., Sigrist(*), S. J.; Rosenmund(*), C.
Proc Natl Acad Sci U S A, 113:11615-11620
(2016)

Tags: Molecular Pharmacology and Cell Biology (Haucke), Molecular and Theoretical Neuroscience (Walter)

Abstract: The tight spatial coupling of synaptic vesicles and voltage-gated Ca2+ channels (CaVs) ensures efficient action potential-triggered neurotransmitter release from presynaptic active zones (AZs). Rab-interacting molecule-binding proteins (RIM-BPs) interact with Ca2+ channels and via RIM with other components of the release machinery. Although human RIM-BPs have been implicated in autism spectrum disorders, little is known about the role of mammalian RIM-BPs in synaptic transmission. We investigated RIM-BP2-deficient murine hippocampal neurons in cultures and slices. Short-term facilitation is significantly enhanced in both model systems. Detailed analysis in culture revealed a reduction in initial release probability, which presumably underlies the increased short-term facilitation. Superresolution microscopy revealed an impairment in CaV2.1 clustering at AZs, which likely alters Ca2+ nanodomains at release sites and thereby affects release probability. Additional deletion of RIM-BP1 does not exacerbate the phenotype, indicating that RIM-BP2 is the dominating RIM-BP isoform at these synapses.

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Leibniz-Forschungsinstitut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP)
Campus Berlin-Buch
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13125 Berlin, Germany
+4930 94793 - 100 
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info(at)fmp-berlin.de

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