FMP Publications

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

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References
Sulindac Sulfide Induces the Formation of Large Oligomeric Aggregates of the Alzheimer's Disease Amyloid-beta Peptide Which Exhibit Reduced Neurotoxicity
Prade(*), E., Barucker(*), C., Sarkar(*), R., Althoff-Ospelt(*), G., Lopez del Amo, J. M., Hossain(*), S., Zhong(*), Y., Multhaup(*), G.; Reif(*), B.
Biochemistry, 55:1839-1849
(2016)

Tags: Solid-State NMR Spectroscopy (Reif)

Abstract: Alzheimer's disease is characterized by deposition of the amyloid beta-peptide (Abeta) in brain tissue of affected individuals. In recent years, many potential lead structures have been suggested that can potentially be used for diagnosis and therapy. However, the mode of action of these compounds is so far not understood. Among these small molecules, the nonsteroidal anti-inflammatory drug (NSAID) sulindac sulfide received a lot of attention. In this manuscript, we characterize the interaction between the monomeric Abeta peptide and the NSAID sulindac sulfide. We find that sulindac sulfide efficiently depletes the pool of toxic oligomers by enhancing the rate of fibril formation. In vitro, sulindac sulfide forms colloidal particles which catalyze the formation of fibrils. Aggregation is immediate, presumably by perturbing the supersaturated Abeta solution. We find that sulindac sulfide induced Abeta aggregates are structurally homogeneous. The C-terminal part of the peptide adopts a beta-sheet structure, whereas the N-terminus is disordered. The salt bridge between D23 and K28 is present, similar as in wild type fibril structures. (13)C-(19)F transferred echo double resonance experiments suggest that sulindac sulfide colocalizes with the Abeta peptide in the aggregate.

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.

Green tea reduces body fat via upregulation of neprilysin
Muenzner, M., Tappenbeck(*), N., Gembardt(*), F., Rülke, R., Furkert, J., Melzig(*), M. F., Siems, W. E., Brockmann(*), G. A.; Walther(*), T.
Int J Obes (Lond), 40:1850-1855
(2016)

Tags: Biochemical Neurobiology (Siems)

Abstract: BACKGROUND/OBJECTIVE: Consumption of green tea has become increasingly popular, particularly because of claimed reduction in body weight. We recently reported that animals with pharmacological inhibition (by candoxatril) or genetic absence of the endopeptidase neprilysin (NEP) develop an obese phenotype. We now investigated the effect of green tea extract (in drinking water) on body weight and body composition and the mediating role of NEP. SUBJECTS/METHODS: To elucidate the role of NEP in mediating the beneficial effects of green tea extract, 'Berlin fat mice' or NEP-deficient mice and their age- and gender-matched wild-type controls received the extract in two different doses (300 or 600 mg kg-1 body weight per day) in the drinking water. RESULTS: In 'Berlin fat mice', 51 days of green tea treatment did not only prevent fat accumulation (control: day 0: 30.5% fat, day 51: 33.1%; NS) but also reduced significant body fat (green tea: day 0: 27.8%, day 51: 20.9%, P<0.01) and body weight below the initial levels. Green tea reduced food intake. This was paralleled by a selective increase in peripheral (in kidney 17%, in intestine 92%), but not central NEP expression and activity, leading to downregulation of orexigens (like galanin and neuropeptide Y (NPY)) known to be physiological substrates of NEP. Consequently, in NEP-knockout mice, green tea extract failed to reduce body fat/weight. CONCLUSIONS: Our data generate experimental proof for the assumed effects of green tea on body weight and the key role for NEP in such process, and thus open a new avenue for the treatment of obesity.

Modes and mechanisms of synaptic vesicle recycling
Soykan, T., Maritzen, T.; Haucke, V.
Curr Opin Neurobiol, 39:17-23
(2016)

Tags: Molecular Pharmacology and Cell Biology (Haucke), Membrane Traffic and Cell Motility (Maritzen)

Abstract: Neurotransmission requires the recycling of synaptic vesicles (SVs) to replenish the SV pool, clear release sites, and maintain presynaptic integrity. In spite of decades of research the modes and mechanisms of SV recycling remain controversial. The identification of clathrin-independent modes of SV recycling such as ultrafast endocytosis has added to the debate. Accumulating evidence further suggests that SV membrane retrieval and the reformation of functional SVs are separable processes. This may allow synapses to rapidly restore membrane surface area over a wide range of stimulations followed by slow reformation of release-competent SVs. One of the future challenges will be to pinpoint the exact mechanisms that link SV recycling modes to synaptic activity patterns at different synapses.

Elm defence against herbivores and pathogens: morphological, chemical and molecular regulation aspects
Buchel(*), K., Fenning(*), T., Gershenzon(*), J., Hilker(*), M.; Meiners, T.
Phytochem Rev, 15:961-983
(2016)

Tags: Department Chemical Biology/ EU-OPENSCREEN

Abstract: Elms (Ulmus spp.) have long been appreciated for their environmental tolerance, landscape and ornamental value, and the quality of their wood. Although elm trees are extremely hardy against abiotic stresses such as wind and pollution, they are susceptible to attacks of biotic stressors. Over 100 phytopathogens and invertebrate pests are associated with elms: fungi, bacteria and insects like beetles and moths, and to a lesser extent aphids, mites, viruses and nematodes. While the biology of the pathogen and insect vector of the Dutch elm disease has been intensively studied, less attention has been paid so far to the defence mechanisms of elms to other biotic stressors. This review highlights knowledge of direct and indirect elm defences against biotic stressors focusing on morphological, chemical and gene regulation aspects. First, we report how morphological defence mechanisms via barrier formation and vessel occlusion prevent colonisation and spread of wood- and bark-inhabiting fungi and bacteria. Second, we outline how secondary metabolites such as terpenoids (volatile terpenoids, mansonones and triterpenoids) and phenolics (lignans, coumarins, flavonoids) in leaves and bark are involved in constitutive and induced chemical defence mechanisms of elms. Third, we address knowledge on how the molecular regulation of elm defence is orchestrated through the interaction of a huge variety of stress- and defence-related genes. We conclude by pointing to the gaps of knowledge on the chemical and molecular mechanisms of elm defence against pest insects and diseases. An in-depth understanding of defence mechanisms of elms will support the development of sustainable integrated management of pests and diseases attacking elms.

Lipid dynamics in boar sperm studied by advanced fluorescence imaging techniques
Schröter(*), F., Jakop(*), U., Teichmann, A., Haralampiev(*), I., Tannert(*), A., Wiesner, B., Müller(*), P.; Müller(*), K.
European biophysics journal : EBJ, 45:149-163
(2016)

Tags: Cellular Imaging (Wiesner)

Abstract: The (re)organization of membrane components is of special importance to prepare mammalian sperm to fertilization. Establishing suitable methods to examine physico-chemical membrane parameters is of high interest. We characterized the behavior of fluorescent (NBD) analogs of sphingomyelin (SM), phosphatidylserine (PS), and cholesterol (Ch) in the acrosomal and postacrosomal macrodomain of boar sperm. Due to their specific transverse membrane distribution, a leaflet-specific investigation of membrane properties is possible. The behavior of lipid analogs in boar sperm was investigated by fluorescence lifetime imaging microscopy (FLIM), fluorescence recovery after photobleaching (FRAP), and fluorescence correlation spectroscopy (FCS). The results were compared with regard to the different temporal and spatial resolution of the methods. For the first time, fluorescence lifetimes of lipid analogs were determined in sperm cell membrane and found to be in a range characteristic for the liquid-disordered phase in artificial lipid membranes. FLIM analyses further indicate a more fluid microenvironment of NBD-Ch and NBD-PS in the postacrosomal compared to the acrosomal region. The concept of a more fluid cytoplasmic leaflet is supported by lower fluorescence lifetime and higher average D values (FCS) for NBD-PS in both head compartments. Whereas FLIM analyses did not indicate coexisting distinct liquid-ordered and -disordered domains in any of the head regions, comparisons between FRAP and FCS measurements suggest the incorporation of NBD-SM as well as NBD-PS in postacrosomal subpopulations with different diffusion velocity. The analog-specific results indicate that the lipid analogs used are suitable to report on the various physicochemical properties of different microenvironments.

Liquid storage of boar semen: Current and future perspectives on the use of cationic antimicrobial peptides to replace antibiotics in semen extenders
Schulze(*), M., Dathe, M., Waberski(*), D.; Müller(*), K.
Theriogenology, 85:39-46
(2016)

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

Abstract: Antibiotics are of great importance in boar semen extenders to ensure long shelf life of spermatozoa and to reduce transmission of pathogens into the female tract. However, the use of antibiotics carries a risk of developing resistant bacterial strains in artificial insemination laboratories and their spread via artificial insemination. Development of multiresistant bacteria is a major concern if mixtures of antibiotics are used in semen extenders. Minimal contamination prevention techniques and surveillance of critical hygiene control points proved to be efficient in reducing bacterial load and preventing development of antibiotic resistance. Nevertheless, novel antimicrobial concepts are necessary for efficient bacterial control in extended boar semen with a minimum risk of evoking antibiotic resistance. Enhanced efforts have been made in recent years in the design and use of antimicrobial peptides (AMPs) as alternatives to conventional antibiotics. The male genital tract harbors a series of endogenic substances with antimicrobial activity and additional functions relevant to the fertilization process. However, exogenic AMPs often exert dose- and time-dependent toxic effects on mammalian spermatozoa. Therefore, it is important that potential newly designed AMPs have only minor impacts on eukaryotic cells. Recently, synthetic magainin derivatives and cyclic hexapeptides were tested for their application in boar semen preservation. Bacterial selectivity, proteolytic stability, thermodynamic resistance, and potential synergistic interaction with conventional antibiotics propel predominantly cyclic hexapeptides into highly promising, leading candidates for further development in semen preservation. The time scale for the development of resistant pathogens cannot be predicted at this moment.

The sclerostin-neutralizing antibody AbD09097 recognizes an epitope adjacent to sclerostin's binding site for the Wnt co-receptor LRP6
Boschert(*), V., Frisch(*), C., Back(*), J. W., van Pee(*), K., Weidauer(*), S. E., Muth(*), E. M., Schmieder, P., Beerbaum, M., Knappik(*), A., Timmerman(*), P.; Mueller(*), T. D.
Open biology, 6
(2016)

Tags: Solution NMR (Schmieder)

Abstract: The glycoprotein sclerostin has been identified as a negative regulator of bone growth. It exerts its function by interacting with the Wnt co-receptor LRP5/6, blocks the binding of Wnt factors and thereby inhibits Wnt signalling. Neutralizing anti-sclerostin antibodies are able to restore Wnt activity and enhance bone growth thereby presenting a new osteoanabolic therapy approach for diseases such as osteoporosis. We have generated various Fab antibodies against human and murine sclerostin using a phage display set-up. Biochemical analyses have identified one Fab developed against murine sclerostin, AbD09097 that efficiently neutralizes sclerostin's Wnt inhibitory activity. In vitro interaction analysis using sclerostin variants revealed that this neutralizing Fab binds to sclerostin's flexible second loop, which has been shown to harbour the LRP5/6 binding motif. Affinity maturation was then applied to AbD09097, providing a set of improved neutralizing Fab antibodies which particularly bind human sclerostin with enhanced affinity. Determining the crystal structure of AbD09097 provides first insights into how this antibody might recognize and neutralize sclerostin. Together with the structure-function relationship derived from affinity maturation these new data will foster the rational design of new and highly efficient anti-sclerostin antibodies for the therapy of bone loss diseases such as osteoporosis.

A phosphoinositide conversion mechanism for exit from endosomes
Ketel, K., Krauss, M., Nicot(*), A. S., Puchkov, D., Wieffer(*), M., Müller(*), R., Subramanian(*), D., Schultz(*), C., Laporte(*), J.; Haucke, V.
Nature, 529:408-412
(2016)

Tags: Molecular Pharmacology and Cell Biology (Haucke), Cellular Imaging (Wiesner/Puchkov)

Abstract: Phosphoinositides are a minor class of short-lived membrane phospholipids that serve crucial functions in cell physiology ranging from cell signalling and motility to their role as signposts of compartmental membrane identity. Phosphoinositide 4-phosphates such as phosphatidylinositol 4-phosphate (PI(4)P) and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) are concentrated at the plasma membrane, on secretory organelles, and on lysosomes, whereas phosphoinositide 3-phosphates, most notably phosphatidylinositol 3-phosphate (PI(3)P), are a hallmark of the endosomal system. Directional membrane traffic between endosomal and secretory compartments, although inherently complex, therefore requires regulated phosphoinositide conversion. The molecular mechanism underlying this conversion of phosphoinositide identity during cargo exit from endosomes by exocytosis is unknown. Here we report that surface delivery of endosomal cargo requires hydrolysis of PI(3)P by the phosphatidylinositol 3-phosphatase MTM1, an enzyme whose loss of function leads to X-linked centronuclear myopathy (also called myotubular myopathy) in humans. Removal of endosomal PI(3)P by MTM1 is accompanied by phosphatidylinositol 4-kinase-2alpha (PI4K2alpha)-dependent generation of PI(4)P and recruitment of the exocyst tethering complex to enable membrane fusion. Our data establish a mechanism for phosphoinositide conversion from PI(3)P to PI(4)P at endosomes en route to the plasma membrane and suggest that defective phosphoinositide conversion at endosomes underlies X-linked centronuclear myopathy caused by mutation of MTM1 in humans.

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.

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