@article{SauerJuranekMarksetal.2019, author = {Sauer, Markus and Juranek, Stefan A. and Marks, James and De Magis, Alessio and Kazemier, Hinke G and Hilbig, Daniel and Benhalevy, Daniel and Wang, Xiantao and Hafner, Markus and Paeschke, Katrin}, title = {DHX36 prevents the accumulation of translationally inactive mRNAs with G4-structures in untranslated regions}, series = {Nature Communications}, volume = {10}, journal = {Nature Communications}, number = {2421}, doi = {10.1038/s41467-019-10432-5}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-227486}, pages = {1-15}, year = {2019}, abstract = {Translation efficiency can be affected by mRNA stability and secondary structures, including G-quadruplex structures (G4s). The highly conserved DEAH-box helicase DHX36/RHAU resolves G4s on DNA and RNA in vitro, however a systems-wide analysis of DHX36 targets and function is lacking. We map globally DHX36 binding to RNA in human cell lines and find it preferentially interacting with G-rich and G4-forming sequences on more than 4500 mRNAs. While DHX36 knockout (KO) results in a significant increase in target mRNA abundance, ribosome occupancy and protein output from these targets decrease, suggesting that they were rendered translationally incompetent. Considering that DHX36 targets, harboring G4s, preferentially localize in stress granules, and that DHX36 KO results in increased SG formation and protein kinase R (PKR/EIF2AK2) phosphorylation, we speculate that DHX36 is involved in resolution of rG4 induced cellular stress.}, language = {en} } @article{HaakeHaackSchaeferetal.2023, author = {Haake, Markus and Haack, Beatrice and Sch{\"a}fer, Tina and Harter, Patrick N. and Mattavelli, Greta and Eiring, Patrick and Vashist, Neha and Wedekink, Florian and Genssler, Sabrina and Fischer, Birgitt and Dahlhoff, Julia and Mokhtari, Fatemeh and Kuzkina, Anastasia and Welters, Marij J. P. and Benz, Tamara M. and Sorger, Lena and Thiemann, Vincent and Almanzar, Giovanni and Selle, Martina and Thein, Klara and Sp{\"a}th, Jacob and Gonzalez, Maria Cecilia and Reitinger, Carmen and Ipsen-Escobedo, Andrea and Wistuba-Hamprecht, Kilian and Eichler, Kristin and Filipski, Katharina and Zeiner, Pia S. and Beschorner, Rudi and Goedemans, Renske and Gogolla, Falk Hagen and Hackl, Hubert and Rooswinkel, Rogier W. and Thiem, Alexander and Romer Roche, Paula and Joshi, Hemant and P{\"u}hringer, Dirk and W{\"o}ckel, Achim and Diessner, Joachim E. and R{\"u}diger, Manfred and Leo, Eugen and Cheng, Phil F. and Levesque, Mitchell P. and Goebeler, Matthias and Sauer, Markus and Nimmerjahn, Falk and Schuberth-Wagner, Christine and Felten, Stefanie von and Mittelbronn, Michel and Mehling, Matthias and Beilhack, Andreas and van der Burg, Sjoerd H. and Riedel, Angela and Weide, Benjamin and Dummer, Reinhard and Wischhusen, J{\"o}rg}, title = {Tumor-derived GDF-15 blocks LFA-1 dependent T cell recruitment and suppresses responses to anti-PD-1 treatment}, series = {Nature Communications}, volume = {14}, journal = {Nature Communications}, doi = {10.1038/s41467-023-39817-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357333}, year = {2023}, abstract = {Immune checkpoint blockade therapy is beneficial and even curative for some cancer patients. However, the majority don't respond to immune therapy. Across different tumor types, pre-existing T cell infiltrates predict response to checkpoint-based immunotherapy. Based on in vitro pharmacological studies, mouse models and analyses of human melanoma patients, we show that the cytokine GDF-15 impairs LFA-1/β2-integrin-mediated adhesion of T cells to activated endothelial cells, which is a pre-requisite of T cell extravasation. In melanoma patients, GDF-15 serum levels strongly correlate with failure of PD-1-based immune checkpoint blockade therapy. Neutralization of GDF-15 improves both T cell trafficking and therapy efficiency in murine tumor models. Thus GDF-15, beside its known role in cancer-related anorexia and cachexia, emerges as a regulator of T cell extravasation into the tumor microenvironment, which provides an even stronger rationale for therapeutic anti-GDF-15 antibody development.}, language = {en} } @article{ZieglerWeissSchmittetal.2017, author = {Ziegler, Sabrina and Weiss, Esther and Schmitt, Anna-Lena and Schlegel, Jan and Burgert, Anne and Terpitz, Ulrich and Sauer, Markus and Moretta, Lorenzo and Sivori, Simona and Leonhardt, Ines and Kurzai, Oliver and Einsele, Hermann and Loeffler, Juergen}, title = {CD56 Is a Pathogen Recognition Receptor on Human Natural Killer Cells}, series = {Scientific Reports}, volume = {7}, journal = {Scientific Reports}, number = {6138}, doi = {10.1038/s41598-017-06238-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170637}, year = {2017}, abstract = {Aspergillus (A.) fumigatus is an opportunistic fungal mold inducing invasive aspergillosis (IA) in immunocompromised patients. Although antifungal activity of human natural killer (NK) cells was shown in previous studies, the underlying cellular mechanisms and pathogen recognition receptors (PRRs) are still unknown. Using flow cytometry we were able to show that the fluorescence positivity of the surface receptor CD56 significantly decreased upon fungal contact. To visualize the interaction site of NK cells and A. fumigatus we used SEM, CLSM and dSTORM techniques, which clearly demonstrated that NK cells directly interact with A. fumigatus via CD56 and that CD56 is re-organized and accumulated at this interaction site time-dependently. The inhibition of the cytoskeleton showed that the receptor re-organization was an active process dependent on actin re-arrangements. Furthermore, we could show that CD56 plays a role in the fungus mediated NK cell activation, since blocking of CD56 surface receptor reduced fungal mediated NK cell activation and reduced cytokine secretion. These results confirmed the direct interaction of NK cells and A. fumigatus, leading to the conclusion that CD56 is a pathogen recognition receptor. These findings give new insights into the functional role of CD56 in the pathogen recognition during the innate immune response.}, language = {en} } @article{MemmelSisarioZoelleretal.2017, author = {Memmel, Simon and Sisario, Dmitri and Z{\"o}ller, Caren and Fiedler, Vanessa and Katzer, Astrid and Heiden, Robin and Becker, Nicholas and Eing, Lorenz and Ferreira, F{\´a}bio L.R. and Zimmermann, Heiko and Sauer, Markus and Flentje, Michael and Sukhorukov, Vladimir L. and Djuzenova, Cholpon S.}, title = {Migration pattern, actin cytoskeleton organization and response to PI3K-, mTOR-, and Hsp90-inhibition of glioblastoma cells with different invasive capacities}, series = {Oncotarget}, volume = {8}, journal = {Oncotarget}, number = {28}, doi = {10.18632/oncotarget.16847}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170719}, pages = {45298-45310}, year = {2017}, abstract = {High invasiveness and resistance to chemo- and radiotherapy of glioblastoma multiforme (GBM) make it the most lethal brain tumor. Therefore, new treatment strategies for preventing migration and invasion of GBM cells are needed. Using two different migration assays, Western blotting, conventional and super-resolution (dSTORM) fluorescence microscopy we examine the effects of the dual PI3K/mTOR-inhibitor PI-103 alone and in combination with the Hsp90 inhibitor NVP-AUY922 and/or irradiation on the migration, expression of marker proteins, focal adhesions and F-actin cytoskeleton in two GBM cell lines (DK-MG and SNB19) markedly differing in their invasive capacity. Both lines were found to be strikingly different in morphology and migration behavior. The less invasive DK-MG cells maintained a polarized morphology and migrated in a directionally persistent manner, whereas the highly invasive SNB19 cells showed a multipolar morphology and migrated randomly. Interestingly, a single dose of 2 Gy accelerated wound closure in both cell lines without affecting their migration measured by single-cell tracking. PI-103 inhibited migration of DK-MG (p53 wt, PTEN wt) but not of SNB19 (p53 mut, PTEN mut) cells probably due to aberrant reactivation of the PI3K pathway in SNB19 cells treated with PI-103. In contrast, NVP-AUY922 exerted strong anti-migratory effects in both cell lines. Inhibition of cell migration was associated with massive morphological changes and reorganization of the actin cytoskeleton. Our results showed a cell line-specific response to PI3K/mTOR inhibition in terms of GBM cell motility. We conclude that anti-migratory agents warrant further preclinical investigation as potential therapeutics for treatment of GBM.}, language = {en} } @article{PaulPauliEhmannetal.2015, author = {Paul, Mila M. and Pauli, Martin and Ehmann, Nadine and Hallermann, Stefan and Sauer, Markus and Kittel, Robert J. and Heckmann, Manfred}, title = {Bruchpilot and Synaptotagmin collaborate to drive rapid glutamate release and active zone differentiation}, series = {Frontiers in Cellular Neuroscience}, volume = {9}, journal = {Frontiers in Cellular Neuroscience}, number = {29}, doi = {10.3389/fncel.2015.00029}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148988}, year = {2015}, abstract = {The active zone (AZ) protein Bruchpilot (Brp) is essential for rapid glutamate release at Drosophila melanogaster neuromuscular junctions (NMJs). Quantal time course and measurements of action potential-waveform suggest that presynaptic fusion mechanisms are altered in brp null mutants (brp\(^{69}\)). This could account for their increased evoked excitatory postsynaptic current (EPSC) delay and rise time (by about 1 ms). To test the mechanism of release protraction at brp\(^{69}\) AZs, we performed knock-down of Synaptotagmin-1 (Syt) via RNAi (syt\(^{KD}\)) in wildtype (wt), brp\(^{69}\) and rab3 null mutants (rab3\(^{rup}\)), where Brp is concentrated at a small number of AZs. At wt and rab3\(^{rup}\) synapses, syt\(^{KD}\) lowered EPSC amplitude while increasing rise time and delay, consistent with the role of Syt as a release sensor. In contrast, syt\(^{KD}\) did not alter EPSC amplitude at brp\(^{69}\) synapses, but shortened delay and rise time. In fact, following syt\(^{KD}\), these kinetic properties were strikingly similar in wt and brp\(^{69}\), which supports the notion that Syt protracts release at brp\(^{69}\) synapses. To gain insight into this surprising role of Syt at brp\(^{69}\) AZs, we analyzed the structural and functional differentiation of synaptic boutons at the NMJ. At tonic type Ib motor neurons, distal boutons contain more AZs, more Brp proteins per AZ and show elevated and accelerated glutamate release compared to proximal boutons. The functional differentiation between proximal and distal boutons is Brp-dependent and reduced after syt\(^{KD}\). Notably, syt\(^{KD}\) boutons are smaller, contain fewer Brp positive AZs and these are of similar number in proximal and distal boutons. In addition, super-resolution imaging via dSTORM revealed that syt\(^{KD}\) increases the number and alters the spatial distribution of Brp molecules at AZs, while the gradient of Brp proteins per AZ is diminished. In summary, these data demonstrate that normal structural and functional differentiation of Drosophila AZs requires concerted action of Brp and Syt.}, language = {en} } @article{GrimmKleinKopeketal.2016, author = {Grimm, Jonathan B. and Klein, Teresa and Kopek, Benjamin G. and Shtengel, Gleb and Hess, Harald F. and Sauer, Markus and Lavis, Luke D.}, title = {Synthesis of a far-red photoactivatable silicon-containing rhodamine for super-resolution microscopy}, series = {Angewandte Chemie International Edition}, volume = {55}, journal = {Angewandte Chemie International Edition}, number = {5}, doi = {10.1002/anie.201509649}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-191069}, pages = {1723-1727}, year = {2016}, abstract = {The rhodamine system is a flexible framework for building small-molecule fluorescent probes. Changing N-substitution patterns and replacing the xanthene oxygen with a dimethylsilicon moiety can shift the absorption and fluorescence emission maxima of rhodamine dyes to longer wavelengths. Acylation of the rhodamine nitrogen atoms forces the molecule to adopt a nonfluorescent lactone form, providing a convenient method to make fluorogenic compounds. Herein, we take advantage of all of these structural manipulations and describe a novel photoactivatable fluorophore based on a Si-containing analogue of Q-rhodamine. This probe is the first example of a "caged" Si-rhodamine, exhibits higher photon counts compared to established localization microscopy dyes, and is sufficiently red-shifted to allow multicolor imaging. The dye is a useful label for super-resolution imaging and constitutes a new scaffold for far-red fluorogenic molecules.}, language = {en} } @article{MarkertBritzProppertetal.2016, author = {Markert, Sebastian Matthias and Britz, Sebastian and Proppert, Sven and Lang, Marietta and Witvliet, Daniel and Mulcahy, Ben and Sauer, Markus and Zhen, Mei and Bessereau, Jean-Louis and Stigloher, Christian}, title = {Filling the gap: adding super-resolution to array tomography for correlated ultrastructural and molecular identification of electrical synapses at the C. elegans connectome}, series = {Neurophotonics}, volume = {3}, journal = {Neurophotonics}, number = {4}, doi = {10.1117/1.NPh.3.4.041802}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-187292}, pages = {041802}, year = {2016}, abstract = {Correlating molecular labeling at the ultrastructural level with high confidence remains challenging. Array tomography (AT) allows for a combination of fluorescence and electron microscopy (EM) to visualize subcellular protein localization on serial EM sections. Here, we describe an application for AT that combines near-native tissue preservation via high-pressure freezing and freeze substitution with super-resolution light microscopy and high-resolution scanning electron microscopy (SEM) analysis on the same section. We established protocols that combine SEM with structured illumination microscopy (SIM) and direct stochastic optical reconstruction microscopy (dSTORM). We devised a method for easy, precise, and unbiased correlation of EM images and super-resolution imaging data using endogenous cellular landmarks and freely available image processing software. We demonstrate that these methods allow us to identify and label gap junctions in Caenorhabditis elegans with precision and confidence, and imaging of even smaller structures is feasible. With the emergence of connectomics, these methods will allow us to fill in the gap-acquiring the correlated ultrastructural and molecular identity of electrical synapses.}, language = {en} } @article{LukešGlatzovaKvičalovaetal.2017, author = {Lukeš, Tom{\´a}š and Glatzov{\´a}, Daniela and Kv{\´i}čalov{\´a}, Zuzana and Levet, Florian and Benda, Aleš and Letschert, Sebastian and Sauer, Markus and Brdička, Tom{\´a}š and Lasser, Theo and Cebecauer, Marek}, title = {Quantifying protein densities on cell membranes using super-resolution optical fluctuation imaging}, series = {Nature Communications}, volume = {8}, journal = {Nature Communications}, doi = {10.1038/s41467-017-01857-x}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172993}, year = {2017}, abstract = {Quantitative approaches for characterizing molecular organization of cell membrane molecules under physiological and pathological conditions profit from recently developed super-resolution imaging techniques. Current tools employ statistical algorithms to determine clusters of molecules based on single-molecule localization microscopy (SMLM) data. These approaches are limited by the ability of SMLM techniques to identify and localize molecules in densely populated areas and experimental conditions of sample preparation and image acquisition. We have developed a robust, model-free, quantitative clustering analysis to determine the distribution of membrane molecules that excels in densely labeled areas and is tolerant to various experimental conditions, i.e. multiple-blinking or high blinking rates. The method is based on a TIRF microscope followed by a super-resolution optical fluctuation imaging (SOFI) analysis. The effectiveness and robustness of the method is validated using simulated and experimental data investigating nanoscale distribution of CD4 glycoprotein mutants in the plasma membrane of T cells.}, language = {en} } @article{VogelLoeschbergerSaueretal.2011, author = {Vogel, Benjamin and L{\"o}schberger, Anna and Sauer, Markus and Hock, Robert}, title = {Cross-linking of DNA through HMGA1 suggests a DNA scaffold}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68865}, year = {2011}, abstract = {Binding of proteins to DNA is usually considered 1D with one protein bound to one DNA molecule. In principle, proteins with multiple DNA binding domains could also bind to and thereby cross-link different DNA molecules. We have investigated this possibility using high-mobility group A1 (HMGA1) proteins, which are architectural elements of chromatin and are involved in the regulation of multiple DNA-dependent processes. Using direct stochastic optical reconstruction microscopy (dSTORM), we could show that overexpression of HMGA1a-eGFP in Cos-7 cells leads to chromatin aggregation. To investigate if HMGA1a is directly responsible for this chromatin compaction we developed a DNA cross-linking assay. We were able to show for the first time that HMGA1a can cross-link DNA directly. Detailed analysis using point mutated proteins revealed a novel DNA cross-linking domain. Electron microscopy indicates that HMGA1 proteins are able to create DNA loops and supercoils in linearized DNA confirming the cross-linking ability of HMGA1a. This capacity has profound implications for the spatial organization of DNA in the cell nucleus and suggests cross-linking activities for additional nuclear proteins.}, subject = {DNA}, language = {en} } @article{AndronicShirakashiPickeletal.2015, author = {Andronic, Joseph and Shirakashi, Ryo and Pickel, Simone U. and Westerling, Katherine M. and Klein, Teresa and Holm, Thorge and Sauer, Markus and Sukhorukov, Vladimir L.}, title = {Hypotonic Activation of the Myo-Inositol Transporter SLC5A3 in HEK293 Cells Probed by Cell Volumetry, Confocal and Super-Resolution Microscopy}, series = {PLoS One}, volume = {10}, journal = {PLoS One}, number = {3}, doi = {10.1371/journal.pone.0119990}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-126408}, year = {2015}, abstract = {Swelling-activated pathways for myo-inositol, one of the most abundant organic osmolytes in mammalian cells, have not yet been identified. The present study explores the SLC5A3 protein as a possible transporter of myo-inositol in hyponically swollen HEK293 cells. To address this issue, we examined the relationship between the hypotonicity-induced changes in plasma membrane permeability to myo-inositol Pino [m/s] and expression/localization of SLC5A3. Pino values were determined by cell volumetry over a wide tonicity range (100-275 mOsm) in myo-inositol-substituted solutions. While being negligible under mild hypotonicity (200-275 mOsm), Pino grew rapidly at osmolalities below 200 mOsm to reach a maximum of ∼3 nm/s at 100-125 mOsm, as indicated by fast cell swelling due to myo-inositol influx. The increase in Pino resulted most likely from the hypotonicity-mediated incorporation of cytosolic SLC5A3 into the plasma membrane, as revealed by confocal fluorescence microscopy of cells expressing EGFP-tagged SLC5A3 and super-resolution imaging of immunostained SLC5A3 by direct stochastic optical reconstruction microscopy (dSTORM). dSTORM in hypotonic cells revealed a surface density of membrane-associated SLC5A3 proteins of 200-2000 localizations/μm2. Assuming SLC5A3 to be the major path for myo-inositol, a turnover rate of 80-800 myo-inositol molecules per second for a single transporter protein was estimated from combined volumetric and dSTORM data. Hypotonic stress also caused a significant upregulation of SLC5A3 gene expression as detected by semiquantitative RT-PCR and Western blot analysis. In summary, our data provide first evidence for swelling-mediated activation of SLC5A3 thus suggesting a functional role of this transporter in hypotonic volume regulation of mammalian cells.}, language = {en} } @article{OwenSauerGaus2012, author = {Owen, Dylan M. and Sauer, Markus and Gaus, Katharina}, title = {Fluorescence localization microscopy}, series = {Communicative \& Integrative Biology}, volume = {5}, journal = {Communicative \& Integrative Biology}, number = {4}, doi = {10.4161/cib.20348}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-124416}, pages = {345-349}, year = {2012}, abstract = {Localization microscopy techniques are super-resolution fluorescence imaging methods based on the detection of individual molecules. Despite the relative simplicity of the microscope setups and the availability of commercial instruments, localization microscopy faces unique challenges. While achieving super-resolution is now routine, issues concerning data analysis and interpretation mean that revealing novel biological insights is not. Here, we outline why data analysis and the design of robust test samples may hold the key to harness the full potential of localization microscopy.}, language = {en} } @article{SchneiderKleinMielichSuessetal.2015, author = {Schneider, Johannes and Klein, Teresa and Mielich-S{\"u}ss, Benjamin and Koch, Gudrun and Franke, Christian and Kuipers, Oskar P. and Kov{\´a}cs, {\´A}kos T. and Sauer, Markus and Lopez, Daniel}, title = {Spatio-temporal Remodeling of Functional Membrane Microdomains Organizes the Signaling Networks of a Bacterium}, series = {PLoS Genetics}, volume = {11}, journal = {PLoS Genetics}, number = {4}, doi = {10.1371/journal.pgen.1005140}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125577}, pages = {e1005140}, year = {2015}, abstract = {Lipid rafts are membrane microdomains specialized in the regulation of numerous cellular processes related to membrane organization, as diverse as signal transduction, protein sorting, membrane trafficking or pathogen invasion. It has been proposed that this functional diversity would require a heterogeneous population of raft domains with varying compositions. However, a mechanism for such diversification is not known. We recently discovered that bacterial membranes organize their signal transduction pathways in functional membrane microdomains (FMMs) that are structurally and functionally similar to the eukaryotic lipid rafts. In this report, we took advantage of the tractability of the prokaryotic model Bacillus subtilis to provide evidence for the coexistence of two distinct families of FMMs in bacterial membranes, displaying a distinctive distribution of proteins specialized in different biological processes. One family of microdomains harbors the scaffolding flotillin protein FloA that selectively tethers proteins specialized in regulating cell envelope turnover and primary metabolism. A second population of microdomains containing the two scaffolding flotillins, FloA and FloT, arises exclusively at later stages of cell growth and specializes in adaptation of cells to stationary phase. Importantly, the diversification of membrane microdomains does not occur arbitrarily. We discovered that bacterial cells control the spatio-temporal remodeling of microdomains by restricting the activation of FloT expression to stationary phase. This regulation ensures a sequential assembly of functionally specialized membrane microdomains to strategically organize signaling networks at the right time during the lifespan of a bacterium.}, language = {en} } @article{AndreskaAufmkolkSaueretal.2014, author = {Andreska, Thomas and Aufmkolk, Sarah and Sauer, Markus and Blum, Robert}, title = {High abundance of BDNF within glutamatergic presynapses of cultured hippocampal neurons}, series = {Frontiers in Cellular Neuroscience}, volume = {8}, journal = {Frontiers in Cellular Neuroscience}, number = {107}, issn = {1662-5102}, doi = {10.3389/fncel.2014.00107}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-119793}, year = {2014}, abstract = {In the mammalian brain, the neurotrophin brain-derived neurotrophic factor (BDNF) has emerged as a key factor for synaptic refinement, plasticity and learning. Although BDNF-induced signaling cascades are well known, the spatial aspects of the synaptic BDNF localization remained unclear. Recent data provide strong evidence for an exclusive presynaptic location and anterograde secretion of endogenous BDNF at synapses of the hippocampal circuit. In contrast, various studies using BDNF overexpression in cultured hippocampal neurons support the idea that postsynaptic elements and other dendritic structures are the preferential sites of BDNF localization and release. In this study we used rigorously tested anti-BDNF antibodies and achieved a dense labeling of endogenous BDNF close to synapses. Confocal microscopy showed natural BDNF close to many, but not all glutamatergic synapses, while neither GABAergic synapses nor postsynaptic structures carried a typical synaptic BDNF label. To visualize the BDNF distribution within the fine structure of synapses, we implemented super resolution fluorescence imaging by direct stochastic optical reconstruction microscopy (dSTORM). Two-color dSTORM images of neurites were acquired with a spatial resolution of ~20 nm. At this resolution, the synaptic scaffold proteins Bassoon and Homer exhibit hallmarks of mature synapses and form juxtaposed bars, separated by a synaptic cleft. BDNF imaging signals form granule-like clusters with a mean size of ~60 nm and are preferentially found within the fine structure of the glutamatergic presynapse. Individual glutamatergic presynapses carried up to 90\% of the synaptic BDNF immunoreactivity, and only a minor fraction of BDNF molecules was found close to the postsynaptic bars. Our data proof that hippocampal neurons are able to enrich and store high amounts of BDNF in small granules within the mature glutamatergic presynapse, at a principle site of synaptic plasticity.}, language = {en} } @article{ProppertWolterHolmetal.2014, author = {Proppert, Sven and Wolter, Steve and Holm, Thorge and Klein, Theresa and van de Linde, Sebastian and Sauer, Markus}, title = {Cubic B-spline calibration for 3D super-resolution measurements using astigmatic imaging}, series = {Optics Express}, volume = {22}, journal = {Optics Express}, number = {9}, issn = {1094-4087}, doi = {10.1364/OE.22.010304}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-119730}, pages = {10304-16}, year = {2014}, abstract = {In recent years three-dimensional (3D) super-resolution fluorescence imaging by single-molecule localization (localization microscopy) has gained considerable interest because of its simple implementation and high optical resolution. Astigmatic and biplane imaging are experimentally simple methods to engineer a 3D-specific point spread function (PSF), but existing evaluation methods have proven problematic in practical application. Here we introduce the use of cubic B-splines to model the relationship of axial position and PSF width in the above mentioned approaches and compare the performance with existing methods. We show that cubic B-splines are the first method that can combine precision, accuracy and simplicity.}, language = {en} } @article{LandoEndesfelderBergeretal.2012, author = {Lando, David and Endesfelder, Ulrike and Berger, Harald and Subramanian, Lakxmi and Dunne, Paul D. and McColl, James and Klenerman, David and Carr, Antony M. and Sauer, Markus and Allshire, Robin C. and Heilemann, Mike and Laue, Ernest D.}, title = {Quantitative single-molecule microscopy reveals that CENP-A\(^{Cnp1}\) deposition occurs during G2 in fission yeast}, series = {Open Biology}, volume = {2}, journal = {Open Biology}, number = {120078}, doi = {10.1098/rsob.120078}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134682}, year = {2012}, abstract = {The inheritance of the histone H3 variant CENP-A in nucleosomes at centromeres following DNA replication is mediated by an epigenetic mechanism. To understand the process of epigenetic inheritance, or propagation of histones and histone variants, as nucleosomes are disassembled and reassembled in living eukaryotic cells, we have explored the feasibility of exploiting photo-activated localization microscopy (PALM). PALM of single molecules in living cells has the potential to reveal new concepts in cell biology, providing insights into stochastic variation in cellular states. However, thus far, its use has been limited to studies in bacteria or to processes occurring near the surface of eukaryotic cells. With PALM, one literally observes and 'counts' individual molecules in cells one-by-one and this allows the recording of images with a resolution higher than that determined by the diffraction of light (the so-called super-resolution microscopy). Here, we investigate the use of different fluorophores and develop procedures to count the centromere-specific histone H3 variant CENP-A\(^{Cnp1}\) with single-molecule sensitivity in fission yeast (Schizosaccharomyces pombe). The results obtained are validated by and compared with ChIP-seq analyses. Using this approach, CENP-A\(^{Cnp1}\) levels at fission yeast (S. pombe) centromeres were followed as they change during the cell cycle. Our measurements show that CENP-A(Cnp1) is deposited solely during the G2 phase of the cell cycle.}, language = {en} } @article{WolfAkrapMargetal.2013, author = {Wolf, Annette and Akrap, Nina and Marg, Berenice and Galliardt, Helena and Heiligentag, Martyna and Humpert, Fabian and Sauer, Markus and Kaltschmidt, Barbara and Kaltschmidt, Christian and Seidel, Thorsten}, title = {Elements of Transcriptional Machinery Are Compatible among Plants and Mammals}, series = {PLoS ONE}, volume = {8}, journal = {PLoS ONE}, number = {1}, doi = {10.1371/journal.pone.0053737}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-131203}, pages = {e53737}, year = {2013}, abstract = {In the present work, the objective has been to analyse the compatibility of plant and human transcriptional machinery. The experiments revealed that nuclear import and export are conserved among plants and mammals. Further it has been shown that transactivation of a human promoter occurs by human transcription factor NF-\(\kappa\) B in plant cells, demonstrating that the transcriptional machinery is highly conserved in both kingdoms. Functionality was also seen for regulatory elements of NF-\(\kappa\) B such as its inhibitor I\(\kappa\)B isoform \(\alpha\) that negatively regulated the transactivation activity of the p50/RelA heterodimer by interaction with NF-\(\kappa\)B in plant cells. Nuclear export of RelA could be demonstrated by FRAP-measurements so that RelA shows nucleo-cytoplasmic shuttling as reported for RelA in mammalian cells. The data reveals the high level of compatibility of human transcriptional elements with the plant transcriptional machinery. Thus, Arabidopsis thaliana mesophyll protoplasts might provide a new heterologous expression system for the investigation of the human NF-\(\kappa\)B signaling pathways. The system successfully enabled the controlled manipulation of NF-\(\kappa\)B activity. We suggest the plant protoplast system as a tool for reconstitution and analyses of mammalian pathways and for direct observation of responses to e. g. pharmaceuticals. The major advantage of the system is the absence of interference with endogenous factors that affect and crosstalk with the pathway.}, language = {en} } @article{KlampCampsNietoetal.2013, author = {Klamp, Tobias and Camps, Marta and Nieto, Benjamin and Guasch, Francesc and Ranasinghe, Rohan T. and Wiedemann, Jens and Petr{\´a}šek, Zdeněk and Schwille, Petra and Klenerman, David and Sauer, Markus}, title = {Highly Rapid Amplification-Free and Quantitative DNA Imaging Assay}, series = {Scientific Reports}, volume = {3}, journal = {Scientific Reports}, number = {1852}, doi = {10.1038/srep01852}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-130500}, year = {2013}, abstract = {There is an urgent need for rapid and highly sensitive detection of pathogen-derivedDNAin a point-of-care (POC) device for diagnostics in hospitals and clinics. This device needs to work in a 'sample-in-result-out' mode with minimum number of steps so that it can be completely integrated into a cheap and simple instrument. We have developed a method that directly detects unamplified DNA, and demonstrate its sensitivity on realistically sized 5 kbp targetDNA fragments of Micrococcus luteus in small sample volumes of 20 mL. The assay consists of capturing and accumulating of target DNA on magnetic beads with specific capture oligonucleotides, hybridization of complementary fluorescently labeled detection oligonucleotides, and fluorescence imaging on a miniaturized wide-field fluorescence microscope. Our simple method delivers results in less than 20 minutes with a limit of detection (LOD) of,5 pMand a linear detection range spanning three orders of magnitude.}, language = {en} } @article{WolterEndesfelderLindeetal.2011, author = {Wolter, Steve and Endesfelder, Ulrike and Linde, Sebastian van de and Heilemann, Mike and Sauer, Markus}, title = {Measuring localization performance of super-resolution algorithms on very active samples}, series = {Optics Express}, journal = {Optics Express}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-85936}, year = {2011}, abstract = {Super-resolution fluorescence imaging based on inglemolecule localization relies critically on the availability of efficient processing algorithms to distinguish, identify, and localize emissions of single fluorophores. In multiple current applications, such as threedimensional, time-resolved or cluster imaging, high densities of fluorophore emissions are common. Here, we provide an analytic tool to test the performance and quality of localization microscopy algorithms and demonstrate that common algorithms encounter difficulties for samples with high fluorophore density. We demonstrate that, for typical single-molecule localization microscopy methods such as dSTORM and the commonly used rapidSTORM scheme, computational precision limits the acceptable density of concurrently active fluorophores to 0.6 per square micrometer and that the number of successfully localized fluorophores per frame is limited to 0.2 per square micrometer.}, language = {en} } @article{DengReinhardHennleinetal.2022, author = {Deng, Chunchu and Reinhard, Sebastian and Hennlein, Luisa and Eilts, Janna and Sachs, Stefan and Doose, S{\"o}ren and Jablonka, Sibylle and Sauer, Markus and Moradi, Mehri and Sendtner, Michael}, title = {Impaired dynamic interaction of axonal endoplasmic reticulum and ribosomes contributes to defective stimulus-response in spinal muscular atrophy}, series = {Translational Neurodegeneration}, volume = {11}, journal = {Translational Neurodegeneration}, number = {1}, issn = {2047-9158}, doi = {10.1186/s40035-022-00304-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300649}, year = {2022}, abstract = {Background: Axonal degeneration and defects in neuromuscular neurotransmission represent a pathological hallmark in spinal muscular atrophy (SMA) and other forms of motoneuron disease. These pathological changes do not only base on altered axonal and presynaptic architecture, but also on alterations in dynamic movements of organelles and subcellular structures that are not necessarily reflected by static histopathological changes. The dynamic interplay between the axonal endoplasmic reticulum (ER) and ribosomes is essential for stimulus-induced local translation in motor axons and presynaptic terminals. However, it remains enigmatic whether the ER and ribosome crosstalk is impaired in the presynaptic compartment of motoneurons with Smn (survival of motor neuron) deficiency that could contribute to axonopathy and presynaptic dysfunction in SMA. Methods: Using super-resolution microscopy, proximity ligation assay (PLA) and live imaging of cultured motoneurons from a mouse model of SMA, we investigated the dynamics of the axonal ER and ribosome distribution and activation. Results: We observed that the dynamic remodeling of ER was impaired in axon terminals of Smn-deficient motoneurons. In addition, in axon terminals of Smn-deficient motoneurons, ribosomes failed to respond to the brain-derived neurotrophic factor stimulation, and did not undergo rapid association with the axonal ER in response to extracellular stimuli. Conclusions: These findings implicate impaired dynamic interplay between the ribosomes and ER in axon terminals of motoneurons as a contributor to the pathophysiology of SMA and possibly also other motoneuron diseases.}, language = {en} } @article{SchlegelSauer2020, author = {Schlegel, Jan and Sauer, Markus}, title = {Hochaufgel{\"o}ste Visualisierung einzelner Molek{\"u}le auf ganzen Zellen}, series = {BIOspektrum}, volume = {7}, journal = {BIOspektrum}, issn = {0947-0867}, doi = {10.1007/s12268-020-1501-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-232365}, pages = {736-738}, year = {2020}, abstract = {Biological systems are dynamic and three-dimensional but many techniques allow only static and two-dimensional observation of cells. We used three-dimensional (3D) lattice light-sheet single-molecule localization microscopy (dSTORM) to investigate the complex interactions and distribution of single molecules in the plasma membrane of whole cells. Different receptor densities of the adhesion receptor CD56 at different parts of the cell highlight the importance and need of three-dimensional observation and analysis techniques.}, language = {de} }