FMP Publications

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

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References

2016

Modulation of Hexadecyl-LPA-Mediated Activation of Mast Cells and Microglia by a Chemical Probe for LPA5
Kozian(*), D. H., von Haeften(*), E., Joho(*), S., Czechtizky(*), W., Anumala, U. R., Roux(*), P., Dudda(*), A., Evers(*), A.; Nazare, M.
Chembiochem, 17:861-865
(2016)

Tags: Medicinal Chemistry (Nazare)

Abstract: Mast cells and microglia play a critical role in innate immunity and inflammation and can be activated by a wide range of endogenous and exogenous stimuli. Lysophosphatidic acid (LPA) has recently been reported to activate mast cells and microglia. Using the human mast cell line HMC-1 and the mouse microglia cell line BV-2, we show that LPA-mediated activation can be prevented by blockade of the LPA receptor 5 (LPA5) in both cell lines. The identification of new LPA5-specific antagonists as tool compounds to probe and modulate the LPA5/LPA axis in relevant in vitro and in vivo assays should contribute to better understanding of the underlying role of LPAs in the development and progression of (neuro-) inflammatory diseases.

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.

Effects of Halide Ions on the Carbamidocyclophane Biosynthesis in Nostoc sp. CAVN2
Preisitsch(*), M., Heiden(*), S. E., Beerbaum, M., Niedermeyer(*), T. H., Schneefeld(*), M., Herrmann(*), J., Kumpfmüller(*), J., Thürmer(*), A., Neidhardt(*), I., Wiesner(*), C., Daniel(*), R., Müller(*), R., Bange(*), F. C., Schmieder, P., Schweder(*), T.; Mundt(*), S.
Mar Drugs, 14:21
(2016)

Tags: Solution NMR (Schmieder)

Abstract: In this study, the influence of halide ions on [7.7]paracyclophane biosynthesis in the cyanobacterium Nostoc sp. CAVN2 was investigated. In contrast to KI and KF, supplementation of the culture medium with KCl or KBr resulted not only in an increase of growth but also in an up-regulation of carbamidocyclophane production. LC-MS analysis indicated the presence of chlorinated, brominated, but also non-halogenated derivatives. In addition to 22 known cylindrocyclophanes and carbamidocyclophanes, 27 putative congeners have been detected. Nine compounds, carbamidocyclophanes M-U, were isolated, and their structural elucidation by 1D and 2D NMR experiments in combination with HRMS and ECD analysis revealed that they are brominated analogues of chlorinated carbamidocyclophanes. Quantification of the carbamidocyclophanes showed that chloride is the preferably utilized halide, but incorporation is reduced in the presence of bromide. Evaluation of the antibacterial activity of 30 [7.7]paracyclophanes and related derivatives against selected pathogenic Gram-positive and Gram-negative bacteria exhibited remarkable effects especially against methicillin- and vancomycin-resistant staphylococci and Mycobacterium tuberculosis. For deeper insights into the mechanisms of biosynthesis, the carbamidocyclophane biosynthetic gene cluster in Nostoc sp. CAVN2 was studied. The gene putatively coding for the carbamoyltransferase has been identified. Based on bioinformatic analyses, a possible biosynthetic assembly is discussed.

Stabilization of bacterially expressed erythropoietin by single site-specific introduction of short branched PEG chains at naturally occurring glycosylation sites
Hoffmann(*), E., Streichert, K., Nischan, N., Seitz(*), C., Brunner(*), T., Schwagerus, S., Hackenberger, C. P.; Rubini(*), M.
Mol Biosyst, 12:1750-1755
(2016)

Tags: Chemische Biologie II (Hackenberger)

Abstract: The covalent attachment of polyethylene glycol (PEG) to therapeutic proteins can improve their physicochemical properties. In this work we utilized the non-natural amino acid p-azidophenylalanine (pAzF) in combination with the chemoselective Staudinger-phosphite reaction to install branched PEG chains to recombinant unglycosylated erythropoietin (EPO) at each single naturally occurring glycosylation site. PEGylation with two short 750 or 2000 Da PEG units at positions 24, 38, or 83 significantly decreased unspecific aggregation and proteolytic degradation while biological activity in vitro was preserved or even increased in comparison to full-glycosylated EPO. This site-specific bioconjugation approach permits to analyse the impact of PEGylation at single positions. These results represent an important step towards the engineering of site-specifically modified EPO variants from bacterial expression with increased therapeutic efficacy.

Bis(arylmethyl)-substituted unsymmetrical phosphites for the synthesis of lipidated peptides via Staudinger-phosphite reactions
Nischan, N., Kasper, M. A., Mathew(*), T.; Hackenberger, C. P.
Org Biomol Chem, 14:7500-7508
(2016)

Tags: Chemical Biology II (Hackenberger)

Abstract: With this study we introduce new unsymmetrical phosphites to obtain lipidated peptide-conjugates starting from easily accessible azide-modified amino acid or peptide precursors. For this purpose, we investigated which substituents at alkyl phosphites lead to the highest formation of mono-alkylated phosphoramidate peptides. We found that phosphites containing one alkyl-chain and two picolyl or benzyl-substituents delivered alkyl phosphoramidate-conjugates in high yields, which also allowed a chemoselective lipidation of an unprotected azido polypeptide. Finally, monolipidated phosphoramidate peptides obtained by the unsymmetrical Staudinger phosphite reaction led to the formation of micelle-like structures and cellular uptake.

Lipopeptide-based micellar and liposomal carriers: Influence of surface charge and particle size on cellular uptake into blood brain barrier cells
Sydow, K., Nikolenko, H., Lorenz, D., Müller(*), R. H.; Dathe, M.
Eur J Pharm Biopharm, 109:130-139
(2016)

Tags: Peptide-Lipid-Interaction/ Peptide Transport (Dathe)

Abstract: Lipopeptide-based micelles and liposomes were found to differ in cell recognition and uptake mode into blood brain barrier (BBB) endothelial cells. Here we analyse the role of size and surface charge of micelles and liposomes composed of different lipopeptide sequences with respect to uptake into human brain capillary (HBMEC) and aortic (HAoEC) endothelial cells. Comparable to the dipalmitoylated apolipoprotein E-derived P2A2, lipopeptides of cationic poly-arginine (P2Rn), poly-lysine (P2Kn) and an anionic glutamic-acid sequence (P2En) self assemble into micelles (12-14nm in diameter) with high surface charge density, and bind to small (SUVs, about 24nm in diameter) and large (LUV, about 100nm in diameter) liposomes at variable lipid to peptide ratios. The interaction pattern of the resulting particles with endothelial cells is highly variable as revealed by confocal laser scanning microscopic (CLSM) and fluorescence assisted cell sorting (FACS) studies. Micelles and SUVs with high P2A2 density are efficiently and selectively internalized into HBMEC. P2Kn micelles strongly accumulate in both the cytosol and at the cell membrane, while the interaction of liposomes tagged with a low amount of P2A2 and P2Kn with the cells was reduced. Anionic micelles seem to dissociate in the presence of cells and P2En molecules incorporate into the cellular membrane whereas the negatively charged liposomes hardly interact with cells. Surprisingly, all poly-R-based particles show high selectivity for HBMEC compared to HAoEC, independent of particle size and peptide surface density. The P2Rn-mediated internalization is highly efficient and partially clathrin-dependent. The oligo-R lipopeptide is considered to be most promising to selectively transport different drug carriers into the blood brain barrier.

Surface Binding of TOTAPOL Assists Structural Investigations of Amyloid Fibrils by Dynamic Nuclear Polarization NMR Spectroscopy
Nagaraj, M., Franks, T. W., Saeidpour(*), S., Schubeis(*), T., Oschkinat, H., Ritter(*), C.; van Rossum, B. J.
Chembiochem, 17:1308-1311
(2016)

Tags: NMR-Supported Structural Biology (Oschkinat)

Abstract: Dynamic nuclear polarization (DNP) NMR can enhance sensitivity but often comes at the price of a substantial loss of resolution. Two major factors affect spectral quality: low-temperature heterogeneous line broadening and paramagnetic relaxation enhancement (PRE) effects. Investigations by NMR spectroscopy, isothermal titration calorimetry (ITC), and EPR revealed a new substantial affinity of TOTAPOL to amyloid surfaces, very similar to that shown by the fluorescent dye thioflavin-T (ThT). As a consequence, DNP spectra with remarkably good resolution and still reasonable enhancement could be obtained at very low TOTAPOL concentrations, typically 400 times lower than commonly employed. These spectra yielded several long-range constraints that were difficult to obtain without DNP. Our findings open up new strategies for structural studies with DNP NMR spectroscopy on amyloids that can bind the biradical with affinity similar to that shown towards ThT.

Chemoselective synthesis and analysis of naturally occurring phosphorylated cysteine peptides
Bertran-Vicente, J., Penkert, M., Nieto-Garcia, O., Jeckelmann(*), J. M., Schmieder, P., Krause, E.; Hackenberger, C. P.
Nat Commun, 7:12703
(2016)

Tags: Chemical Biology II (Hackenberger), Mass Spectrometry (Krause, E), Solution NMR (Schmieder)

Abstract: In contrast to protein O-phosphorylation, studying the function of the less frequent N- and S-phosphorylation events have lagged behind because they have chemical features that prevent their manipulation through standard synthetic and analytical methods. Here we report on the development of a chemoselective synthetic method to phosphorylate Cys side-chains in unprotected peptides. This approach makes use of a reaction between nucleophilic phosphites and electrophilic disulfides accessible by standard methods. We achieve the stereochemically defined phosphorylation of a Cys residue and verify the modification using electron-transfer higher-energy dissociation (EThcD) mass spectrometry. To demonstrate the use of the approach in resolving biological questions, we identify an endogenous Cys phosphorylation site in IICB(Glc), which is known to be involved in the carbohydrate uptake from the bacterial phosphotransferase system (PTS). This new chemical and analytical approach finally allows further investigating the functions and significance of Cys phosphorylation in a wide range of crucial cellular processes.

Inhibition of the key enzyme of sialic acid biosynthesis by C6-Se modified N-acetylmannosamine analogs
Nieto-Garcia, O., Wratil(*), P. R., Nguyen(*), L. D., Bohrsch(*), V., Hinderlich(*), S., Reutter(*), W.; Hackenberger, C. P. R.
Chem Sci, 7:3928-3933
(2016)

Tags: Chemical Biology II (Hackenberger)

Abstract: Synthetically accessible C6-analogs of N-acetylmannosamine (ManNAc) were tested as potential inhibitors of the bifunctional UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase (GNE/MNK), the key enzyme of sialic acid biosynthesis. Enzymatic experiments revealed that the modification introduced at the C6 saccharide position strongly influences the inhibitory potency. A C6-ManNAc diselenide dimer showed the strongest kinase inhibition in the low mu M range among all the substrates tested and successfully reduced cell surface sialylation in Jurkat cells.

SORLA regulates calpain-dependent degradation of synapsin
Hartl(*), D., Nebrich(*), G., Klein(*), O., Stephanowitz, H., Krause, E.; Rohe(*), M.
Alzheimers Dement, 12:952-963
(2016)

Tags: Mass Spectrometry (Krause, E.)

Abstract: INTRODUCTION: Sorting-related receptor with A-type repeats (SORLA) is an intracellular sorting receptor in neurons and a major risk factor for Alzheimer disease. METHODS: Here, we performed global proteome analyses in the brain of SORLA-deficient mice followed by biochemical and histopathologic studies to identify novel neuronal pathways affected by receptor dysfunction. RESULTS: We demonstrate that the lack of SORLA results in accumulation of phosphorylated synapsins in cortex and hippocampus. We propose an underlying molecular mechanism by demonstrating that SORLA interacts with phosphorylated synapsins through 14-3-3 adaptor proteins to deliver synapsins to calpain-mediated proteolytic degradation. DISCUSSION: Our results suggest a novel function for SORLA which is in control of synapsin degradation, potentially impacting on synaptic vesicle endocytosis and/or exocytosis.

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Leibniz-Forschungsinstitut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP)
Campus Berlin-Buch
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