TY - JOUR A1 - Tauscher, Sabine A1 - Nakagawa, Hitoshi A1 - Völker, Katharina A1 - Werner, Franziska A1 - Krebes, Lisa A1 - Potapenko, Tamara A1 - Doose, Sören A1 - Birkenfeld, Andreas L. A1 - Baba, Hideo A. A1 - Kuhn, Michaela T1 - β Cell-specific deletion of guanylyl cyclase A, the receptor for atrial natriuretic peptide, accelerates obesity-induced glucose intolerance in mice JF - Cardiovascular Diabetology N2 - Background: The cardiac hormones atrial (ANP) and B-type natriuretic peptides (BNP) moderate arterial blood pressure and improve energy metabolism as well as insulin sensitivity via their shared cGMP-producing guanylyl cyclase-A (GC-A) receptor. Obesity is associated with impaired NP/GC-A/cGMP signaling, which possibly contributes to the development of type 2 diabetes and its cardiometabolic complications. In vitro, synthetic ANP, via GC-A, stimulates glucose-dependent insulin release from cultured pancreatic islets and β-cell proliferation. However, the relevance for systemic glucose homeostasis in vivo is not known. To dissect whether the endogenous cardiac hormones modulate the secretory function and/or proliferation of β-cells under (patho)physiological conditions in vivo, here we generated a novel genetic mouse model with selective disruption of the GC-A receptor in β-cells. Methods: Mice with a floxed GC-A gene were bred to Rip-CreTG mice, thereby deleting GC-A selectively in β-cells (β GC-A KO). Weight gain, glucose tolerance, insulin sensitivity, and glucose-stimulated insulin secretion were monitored in normal diet (ND)- and high-fat diet (HFD)-fed mice. β-cell size and number were measured by immunofluorescence-based islet morphometry. Results: In vitro, the insulinotropic and proliferative actions of ANP were abolished in islets isolated from β GC-A KO mice. Concordantly, in vivo, infusion of BNP mildly enhanced baseline plasma insulin levels and glucose-induced insulin secretion in control mice. This effect of exogenous BNP was abolished in β GC-A KO mice, corroborating the efficient inactivation of the GC-A receptor in β-cells. Despite this under physiological, ND conditions, fasted and fed insulin levels, glucose-induced insulin secretion, glucose tolerance and β-cell morphology were similar in β GC-A KO mice and control littermates. However, HFD-fed β GC-A KO animals had accelerated glucose intolerance and diminished adaptative β-cell proliferation. Conclusions: Our studies of β GC-A KO mice demonstrate that the cardiac hormones ANP and BNP do not modulate β-cell's growth and secretory functions under physiological, normal dietary conditions. However, endogenous NP/GC-A signaling improves the initial adaptative response of β-cells to HFD-induced obesity. Impaired β-cell NP/GC-A signaling in obese individuals might contribute to the development of type 2 diabetes. KW - cylic GMP KW - guanylyl cyclase-A KW - insulin KW - natriuretic peptides KW - obesity KW - β-cells Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176322 VL - 17 IS - 103 ER - TY - JOUR A1 - Rubio-Cosials, Anna A1 - Schulz, Eike C. A1 - Lambertsen, Lotte A1 - Smyshlyaev, Georgy A1 - Rojas-Cordova, Carlos A1 - Forslund, Kristoffer A1 - Karaca, Ezgi A1 - Bebel, Aleksandra A1 - Bork, Peer A1 - Barabas, Orsolya T1 - Transposase-DNA Complex Structures Reveal Mechanisms for Conjugative Transposition of Antibiotic Resistance JF - Cell N2 - Conjugative transposition drives the emergence of multidrug resistance in diverse bacterial pathogens, yet the mechanisms are poorly characterized. The Tn1549 conjugative transposon propagates resistance to the antibiotic vancomycin used for severe drug-resistant infections. Here, we present four high-resolution structures of the conserved Y-transposase of Tn1549 complexed with circular transposon DNA intermediates. The structures reveal individual transposition steps and explain how specific DNA distortion and cleavage mechanisms enable DNA strand exchange with an absolute minimum homology requirement. This appears to uniquely allow Tn916-like conjugative transposons to bypass DNA homology and insert into diverse genomic sites, expanding gene transfer. We further uncover a structural regulatory mechanism that prevents premature cleavage of the transposon DNA before a suitable target DNA is found and generate a peptide antagonist that interferes with the transposase-DNA structure to block transposition. Our results reveal mechanistic principles of conjugative transposition that could help control the spread of antibiotic resistance genes. KW - DNA complex KW - crystallography KW - Tn1549 transposon KW - Tn916-like transposon family KW - conjugative transposition KW - tyrosine recombinase KW - antibiotic resistance KW - gene transfer KW - vancomycin KW - multidrug-resistant bacteria Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-227085 VL - 173 IS - 1 ER - TY - JOUR A1 - Christopher D., Pull A1 - Ugelvig, Line V. A1 - Wiesenhofer, Florian A1 - Anna V., Grasse A1 - Tragust, Simon A1 - Schmitt, Thomas A1 - Brown, Mark JF A1 - Cremer, Sylvia T1 - Destructive disinfection of infected brood prevents systemic disease spread in ant colonies JF - eLIFE N2 - In social groups, infections have the potential to spread rapidly and cause disease outbreaks. Here, we show that in a social insect, the ant Lasius neglectus, the negative consequences of fungal infections (Metarhizium brunneum) can be mitigated by employing an efficient multicomponent behaviour, termed destructive disinfection, which prevents further spread of the disease through the colony. Ants specifically target infected pupae during the pathogens non-contagious incubation period, utilising chemical 'sickness cues' emitted by pupae. They then remove the pupal cocoon, perforate its cuticle and administer antimicrobial poison, which enters the body and prevents pathogen replication from the inside out. Like the immune system of a metazoan body that specifically targets and eliminates infected cells, ants destroy infected brood to stop the pathogen completing its lifecycle, thus protecting the rest of the colony. Hence, in an analogous fashion, the same principles of disease defence apply at different levels of biological organisation. KW - division of labor KW - Fungal cell-walls KW - Leaf cutting ants KW - Metarhizium anisopliae KW - Beauveria bassiana Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-223728 VL - 7 ER - TY - JOUR A1 - Keller, Alexander A1 - Brandel, Annette A1 - Becker, Mira C. A1 - Balles, Rebecca A1 - Abdelmohsen, Usama Ramadan A1 - Ankenbrand, Markus J. A1 - Sickel, Wiebke T1 - Wild bees and their nests host Paenibacillus bacteria with functional potential of avail JF - Microbiome N2 - Background: In previous studies, the gram-positive firmicute genus Paenibacillus was found with significant abundances in nests of wild solitary bees. Paenibacillus larvae is well-known for beekeepers as a severe pathogen causing the fatal honey bee disease American foulbrood, and other members of the genus are either secondary invaders of European foulbrood or considered a threat to honey bees. We thus investigated whether Paenibacillus is a common bacterium associated with various wild bees and hence poses a latent threat to honey bees visiting the same flowers. Results: We collected 202 samples from 82 individuals or nests of 13 bee species at the same location and screened each for Paenibacillus using high-throughput sequencing-based 16S metabarcoding. We then isolated the identified strain Paenibacillus MBD-MB06 from a solitary bee nest and sequenced its genome. We did find conserved toxin genes and such encoding for chitin-binding proteins, yet none specifically related to foulbrood virulence or chitinases. Phylogenomic analysis revealed a closer relationship to strains of root-associated Paenibacillus rather than strains causing foulbrood or other accompanying diseases. We found anti-microbial evidence within the genome, confirmed by experimental bioassays with strong growth inhibition of selected fungi as well as gram-positive and gram-negative bacteria. Conclusions: The isolated wild bee associate Paenibacillus MBD-MB06 is a common, but irregularly occurring part of wild bee microbiomes, present on adult body surfaces and guts and within nests especially in megachilids. It was phylogenetically and functionally distinct from harmful members causing honey bee colony diseases, although it shared few conserved proteins putatively toxic to insects that might indicate ancestral predisposition for the evolution of insect pathogens within the group. By contrast, our strain showed anti-microbial capabilities and the genome further indicates abilities for chitin-binding and biofilm-forming, suggesting it is likely a useful associate to avoid fungal penetration of the bee cuticula and a beneficial inhabitant of nests to repress fungal threats in humid and nutrient-rich environments of wild bee nests. KW - 16S metabarcoding KW - American foulbrood KW - anti-microbial activit KW - bacterial genomics KW - bioassays KW - European foulbrood KW - Paenibacterin KW - phylogenomics KW - bee disease KW - pathogen vector Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177554 VL - 6 IS - 229 ER - TY - JOUR A1 - Ranger, Christopher M. A1 - Biedermann, Peter HW A1 - Phuntumart, Vipaporn A1 - Beligala, Gayathri U. A1 - Ghosh, Satyaki A1 - Palmquist, Debra E. A1 - Mueller, Robert A1 - Barnett, Jenny A1 - Schultz, Peter B. A1 - Reding, Michael E. A1 - Benz, J. Philipp T1 - Symbiont selection via alcohol benefits fungus farming by ambrosia beetles JF - Proceedings of the National Academy of Sciences N2 - Animal-microbe mutualisms are typically maintained by vertical symbiont transmission or partner choice. A third mechanism, screening of high-quality symbionts, has been predicted in theory, but empirical examples are rare. Here we demonstrate that ambrosia beetles rely on ethanol within host trees for promoting gardens of their fungal symbiont and producing offspring. Ethanol has long been known as the main attractant for many of these fungus-farming beetles as they select host trees in which they excavate tunnels and cultivate fungal gardens. More than 300 attacks by Xylosandrus germanus and other species were triggered by baiting trees with ethanol lures, but none of the foundresses established fungal gardens or produced broods unless tree tissues contained in vivo ethanol resulting from irrigation with ethanol solutions. More X. germanus brood were also produced in a rearing substrate containing ethanol. These benefits are a result of increased food supply via the positive effects of ethanol on food-fungus biomass. Selected Ambrosiella and Raffaelea fungal isolates from ethanol-responsive ambrosia beetles profited directly and indirectly by (i) a higher biomass on medium containing ethanol, (ii) strong alcohol dehydrogenase enzymatic activity, and (iii) a competitive advantage over weedy fungal garden competitors (Aspergillus, Penicillium) that are inhibited by ethanol. As ambrosia fungi both detoxify and produce ethanol, they may maintain the selectivity of their alcohol-rich habitat for their own purpose and that of other ethanol-resistant/producing microbes. This resembles biological screening of beneficial symbionts and a potentially widespread, unstudied benefit of alcohol-producing symbionts (e.g., yeasts) in other microbial symbioses. KW - fungus-farming insects KW - plant-insect-microbe interactions KW - symbiosis KW - insect-fungus mutualism KW - host screening Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224953 VL - 115 IS - 17 ER - TY - JOUR A1 - Batzke, Katharina A1 - Büchel, Gabriele A1 - Hansen, Wiebke A1 - Schramm, Alexander T1 - TrkB-target Galectin-1 impairs immune activation and radiation responses in neuroblastoma: implications for tumour therapy JF - International Journal of Molecular Sciences N2 - Galectin-1 (Gal-1) has been described to promote tumour growth by inducing angiogenesis and to contribute to the tumour immune escape. We had previously identified up-regulation of Gal-1 in preclinical models of aggressive neuroblastoma (NB), the most common extracranial tumour of childhood. While Gal-1 did not confer a survival advantage in the absence of exogenous stressors, Gal-1 contributed to enhanced cell migratory and invasive properties. Here, we review these findings and extend them by analyzing Gal-1 mediated effects on immune cell regulation and radiation resistance. In line with previous results, cell autonomous effects as well as paracrine functions contribute to Gal-1 mediated pro-tumourigenic functions. Interfering with Gal-1 functions in vivo will add to a better understanding of the role of the Gal-1 axis in the complex tumour-host interaction during immune-, chemo- and radiotherapy of neuroblastoma. KW - Galectin-1 KW - radiation response KW - neuroblastoma Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-285097 SN - 1422-0067 VL - 19 IS - 3 ER - TY - JOUR A1 - Ribitsch, Iris A1 - Peham, Christian A1 - Ade, Nicole A1 - Duerr, Julia A1 - Handschuh, Stephan A1 - Schramel, Johannes Peter A1 - Vogl, Claus A1 - Walles, Heike A1 - Egerbacher, Monika A1 - Jenner, Florian T1 - Structure-Function relationships of equine menisci JF - PLoS ONE N2 - Meniscal pathologies are among the most common injuries of the femorotibial joint in both human and equine patients. Pathological forces and ensuing injuries of the cranial horn of the equine medial meniscus are considered analogous to those observed in the human posterior medial horn. Biomechanical properties of human menisci are site-and depth-specific. However, the influence of equine meniscus topography and composition on its biomechanical properties is yet unknown. A better understanding of equine meniscus composition and biomechanics could advance not only veterinary therapies for meniscus degeneration or injuries, but also further substantiate the horse as suitable translational animal model for (human) meniscus tissue engineering. Therefore, the aim of this study was to investigate the composition and structure of the equine knee meniscus in a site-and age-specific manner and their relationship with potential site-specific biomechanical properties. The meniscus architecture was investigated histologically. Biomechanical testing included evaluation of the shore hardness (SH), stiffness and energy loss of the menisci. The SH was found to be subjected to both age and site-specific changes, with an overall higher SH of the tibial meniscus surface and increase in SH with age. Stiffness and energy loss showed neither site nor age related significant differences. The macroscopic and histologic similarities between equine and human menisci described in this study, support continued research in this field. KW - Human Medial Meniscus KW - Articular-Cartilage KW - Biomechanical Properties KW - Compressive Properties KW - Human Knee KW - Collagen KW - Injuries KW - Models KW - Repair KW - Osteoarthritis Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225214 VL - 13 IS - 3 ER - TY - JOUR A1 - Scheib, Ulrike A1 - Broser, Matthias A1 - Constantin, Oana M. A1 - Yang, Shang A1 - Gao, Shiqiang A1 - Mukherjee, Shatanik A1 - Stehfest, Katja A1 - Nagel, Georg A1 - Gee, Christine E. A1 - Hegemann, Peter T1 - Rhodopsin-cyclases for photocontrol of cGMP/cAMP and 2.3 Å structure of the adenylyl cyclase domain JF - Nature Communications N2 - The cyclic nucleotides cAMP and cGMP are important second messengers that orchestrate fundamental cellular responses. Here, we present the characterization of the rhodopsinguanylyl cyclase from Catenaria anguillulae (CaRhGC), which produces cGMP in response to green light with a light to dark activity ratio > 1000. After light excitation the putative signaling state forms with tau = 31 ms and decays with tau = 570 ms. Mutations (up to 6) within the nucleotide binding site generate rhodopsin-adenylyl cyclases (CaRhACs) of which the double mutated YFP-CaRhAC (E497K/C566D) is the most suitable for rapid cAMP production in neurons. Furthermore, the crystal structure of the ligand-bound AC domain (2.25 angstrom) reveals detailed information about the nucleotide binding mode within this recently discovered class of enzyme rhodopsin. Both YFP-CaRhGC and YFP-CaRhAC are favorable optogenetic tools for non-invasive, cell-selective, and spatio-temporally precise modulation of cAMP/cGMP with light. KW - Enzymes KW - Molecular biophysics KW - Molecular neuroscience KW - X-ray crystallography Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228517 VL - 9 ER - TY - JOUR A1 - Rat, Charlotte A1 - Heiby, Julia C. A1 - Bunz, Jessica P. A1 - Neuweiler, Hannes T1 - Two-step self-assembly of a spider silk molecular clamp JF - Nature Communications N2 - Web spiders synthesize silk fibers of unique strength and extensibility through the controlled self-assembly of protein building blocks, so-called spidroins. The spidroin C-terminal domain is highly conserved and connects two polypeptide chains through formation of an all-helical, intertwined dimer. Here we use contact-induced fluorescence self-quenching and resonance energy transfer in combination with far-UV circular dichroism spectroscopy as three orthogonal structural probes to dissect the mechanism of folding and dimerization of a spidroin C-terminal domain from the major ampullate gland of the nursery web spider Euprosthenops australis. We show that helices forming the dimer core assemble very rapidly and fold on association. Subsequently, peripheral helices fold and dock slowly onto the preformed core. Lability of outer helices facilitates formation of a highly expanded, partially folded dimer. The high end-to-end distance of chain termini in the partially folded dimer suggests an extensibility module that contributes to elasticity of spider silk. KW - Circular dichroism KW - Fluorescence spectroscopy KW - Biokinetics Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225016 VL - 9 ER - TY - JOUR A1 - Reis, Helena A1 - Schwebs, Marie A1 - Dietz, Sabrina A1 - Janzen, Christian J. A1 - Butter, Falk T1 - TelAP1 links telomere complexes with developmental expression site silencing in African trypanosomes JF - Nucleic Acids Research N2 - During its life cycle, Trypanosoma brucei shuttles between a mammalian host and the tsetse fly vector. In the mammalian host, immune evasion of T. brucei bloodstream form (BSF) cells relies on antigenic variation, which includes monoallelic expression and periodic switching of variant surface glycoprotein (VSG) genes. The active VSG is transcribed from only 1 of the 15 subtelomeric expression sites (ESs). During differentiation from BSF to the insect-resident procyclic form (PCF), the active ES is transcriptionally silenced. We used mass spectrometry-based interactomics to determine the composition of telomere protein complexes in T. brucei BSF and PCF stages to learn more about the structure and functions of telomeres in trypanosomes. Our data suggest a different telomere complex composition in the two forms of the parasite. One of the novel telomere-associated proteins, TelAP1, forms a complex with telomeric proteins TbTRF, TbRAP1 and TbTIF2 and influences ES silencing kinetics during developmental differentiation. KW - Gene Regulation KW - Chromatin and Epigenetics Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225180 VL - 46 IS - 6 ER -