@article{PutraNeuberReichetzederetal.2014,
  author    = {Putra, Sulistyo Emantoko Dwi and Neuber, Corinna and Reichetzeder, Christoph and Hocher, Berthold and Kleuser, Burkhard},
  title     = {Analysis of genomic DNA methylation levels in human placenta using liquid Chromatography-Electrospray ionization tandem mass spectrometry},
  series = {Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry and pharmacology},
  volume    = {33},
  journal   = {Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry and pharmacology},
  number    = {4},
  publisher = {Karger},
  address   = {Basel},
  issn      = {1015-8987},
  doi       = {10.1159/000358666},
  pages     = {945 -- 952},
  year      = {2014},
  abstract  = {Background: DNA-methylation is a common epigenetic tool which plays a crucial role in gene regulation and is essential for cell differentiation and embryonic development. The placenta is an important organ where gene activity can be regulated by epigenetic DNA modifications, including DNA methylation. This is of interest as, the placenta is the interface between the fetus and its environment, the mother. Exposure to environmental toxins and nutrition during pregnancy may alter DNA methylation of the placenta and subsequently placental function and as a result the phenotype of the offspring. The aim of this study was to develop a reliable method to quantify DNA methylation in large clinical studies. This will be a tool to analyze the degree of DNA methylation in the human placenta in relationship to clinical readouts. Methods: Liquid chromatography-electrospray ionization/multi-stage mass spectrometry (LC-ESI/MS/MS) technique was used for the quantification of the 5dmC/dG ratio in placentas from 248 healthy pregnancies. We were able to demonstrate that this method is a reliable and stable way to determine global placental DNA methylation in large clinical trials. Results/Conclusion: The degree of placental DNA methylation seen in our pilot study varies substantially from 2\% to 5\%. The clinical implications of this variation need to be demonstrated in adequately powered large studies.},
  language  = {en}
}
@inproceedings{ArltSchwiebsPfarretal.2014,
  author    = {Arlt, Olga and Schwiebs, Anja and Pfarr, Kathrin and Ranglack, Annika and Bouzas, Ferreiros Nerea and Schreiber, Yannick and Neuber, Corinna and Kleuser, Burkhard and Pfeilschifter, Josef M. and Radeke, Heinfried H.},
  title     = {Dynamic interaction between sphingolipid enzymes, S1P and inflammatory cytokine regulation in dendritic cells},
  series = {NAUNYN-SCHMIEDEBERGS ARCHIVES OF PHARMACOLOGY},
  volume    = {387},
  booktitle = {NAUNYN-SCHMIEDEBERGS ARCHIVES OF PHARMACOLOGY},
  publisher = {Springer},
  address   = {New York},
  issn      = {0028-1298},
  pages     = {S91 -- S91},
  year      = {2014},
  language  = {en}
}
@article{ImeriFalleggerZivkovicetal.2014,
  author    = {Imeri, Faik and Fallegger, Daniel and Zivkovic, Aleksandra and Schwalm, Stephanie and Enzmann, Gaby and Blankenbach, Kira and Heringdorf, Dagmar Meyer Zu and Homann, Thomas and Kleuser, Burkhard and Pfeilschifter, Josef and Engelhardt, Britta and Stark, Holger and Huwiler, Andrea},
  title     = {Novel oxazolo-oxazole derivatives of FTY720 reduce endothelial cell permeability, immune cell chemotaxis and symptoms of experimental autoimmune encephalomyelitis in mice},
  series = {Neuropharmacology},
  volume    = {85},
  journal   = {Neuropharmacology},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0028-3908},
  doi       = {10.1016/j.neuropharm.2014.05.012},
  pages     = {314 -- 327},
  year      = {2014},
  abstract  = {The immunomodulatory FTY720 (fingolimod) is presently approved for the treatment of relapsing-remitting multiple sclerosis. It is a prodrug that acts by modulating sphingosine 1-phosphate (S1P) receptor signaling. In this study, we have developed and characterized two novel oxazolo-oxazole derivatives of FTY720, ST-968 and the oxy analog ST-1071, which require no preceding activating phosphorylation, and proved to be active in intact cells and triggered S1P(1) and S1P(3), but not S1P(2), receptor internalization as a result of receptor activation. Functionally, ST-968 and ST-1071 acted similar to FTY720 to abrogate S1P-triggered chemotaxis of mouse splenocytes, mouse T cells and human U937 cells, and reduced TNFa- and LPS-stimulated endothelial cell permeability. The compounds also reduced TNF alpha-induced ICAM-1 and VCAM-1 mRNA expression, but restored TNF alpha-mediated downregulation of PECAM-1 mRNA expression. In an in vivo setting, the application of ST-968 or ST-1071 to mice resulted in a reduction of blood lymphocytes and significantly reduced the clinical symptoms of experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice comparable to FTY720 either by prophylactic or therapeutic treatment. In parallel to the reduced clinical symptoms, infiltration of immune cells in the brain was strongly reduced, and in isolated tissues of brain and spinal cord, the mRNA and protein expressions of ICAM-1 and VCAM-1, as well as of matrix metalloproteinase-9 were reduced by all compounds, whereas PECAM-1 and tissue inhibitor of metalloproteinase TIMP-1 were upregulated. In summary, the data suggest that these novel butterfly derivatives of FTY720 could have considerable implication for future therapies of multiple sclerosis and other autoimmune diseases. (C) 2014 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{KellerCatalaLehnenHuebneretal.2014,
  author    = {Keller, Johannes and Catala-Lehnen, Philip and Huebner, Antje K. and Jeschke, Anke and Heckt, Timo and Lueth, Anja and Krause, Matthias and Koehne, Till and Albers, Joachim and Schulze, Jochen and Schilling, Sarah and Haberland, Michael and Denninger, Hannah and Neven, Mona and Hermans-Borgmeyer, Irm and Streichert, Thomas and Breer, Stefan and Barvencik, Florian and Levkau, Bodo and Rathkolb, Birgit and Wolf, Eckhard and Calzada-Wack, Julia and Neff, Frauke and Gailus-Durner, Valerie and Fuchs, Helmut and de Angelis, Martin Hrabe and Klutmann, Susanne and Tsourdi, Elena and Hofbauer, Lorenz C. and Kleuser, Burkhard and Chun, Jerold and Schinke, Thorsten and Amling, Michael},
  title     = {Calcitonin controls bone formation by inhibiting the release of sphingosine 1-phosphate from osteoclasts},
  series = {Nature Communications},
  volume    = {5},
  journal   = {Nature Communications},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {2041-1723},
  doi       = {10.1038/ncomms6215},
  pages     = {13},
  year      = {2014},
  abstract  = {The hormone calcitonin (CT) is primarily known for its pharmacologic action as an inhibitor of bone resorption, yet CT-deficient mice display increased bone formation. These findings raised the question about the underlying cellular and molecular mechanism of CT action. Here we show that either ubiquitous or osteoclast-specific inactivation of the murine CT receptor (CTR) causes increased bone formation. CT negatively regulates the osteoclast expression of Spns2 gene, which encodes a transporter for the signalling lipid sphingosine 1-phosphate (S1P). CTR-deficient mice show increased S1P levels, and their skeletal phenotype is normalized by deletion of the S1P receptor S1P(3). Finally, pharmacologic treatment with the nonselective S1P receptor agonist FTY720 causes increased bone formation in wild-type, but not in S1P(3)-deficient mice. This study redefines the role of CT in skeletal biology, confirms that S1P acts as an osteoanabolic molecule in vivo and provides evidence for a pharmacologically exploitable crosstalk between osteoclasts and osteoblasts.},
  language  = {en}
}
@inproceedings{BaranyaiGoedtelArmbrustNestleretal.2014,
  author    = {Baranyai, Dorothea and Goedtel-Armbrust, Ute and Nestler, Sebastian and Kleuser, Burkhard and Wojnowski, Leszek},
  title     = {A role for cutaneous CYP3A in vitamin D homeostasis?},
  series = {NAUNYN-SCHMIEDEBERGS ARCHIVES OF PHARMACOLOGY},
  volume    = {387},
  booktitle = {NAUNYN-SCHMIEDEBERGS ARCHIVES OF PHARMACOLOGY},
  publisher = {Springer},
  address   = {New York},
  issn      = {0028-1298},
  pages     = {S27 -- S27},
  year      = {2014},
  language  = {en}
}
@article{SicKrausMadletal.2014,
  author    = {Sic, Heiko and Kraus, Helene and Madl, Josef and Flittner, Karl-Andreas and von Muenchow, Audrey Lilly and Pieper, Kathrin and Rizzi, Marta and Kienzler, Anne-Kathrin and Ayata, Korcan and Rauer, Sebastian and Kleuser, Burkhard and Salzer, Ulrich and Burger, Meike and Zirlik, Katja and Lougaris, Vassilios and Plebani, Alessandro and Roemer, Winfried and Loeffler, Christoph and Scaramuzza, Samantha and Villa, Anna and Noguchi, Emiko and Grimbacher, Bodo and Eibel, Hermann},
  title     = {Sphingosine-1-phosphate receptors control B-cell migration through signaling components associated with primary immunodeficiencies, chronic lymphocytic leukemia, and multiple sclerosis},
  series = {The journal of allergy and clinical immunology},
  volume    = {134},
  journal   = {The journal of allergy and clinical immunology},
  number    = {2},
  publisher = {Elsevier},
  address   = {New York},
  issn      = {0091-6749},
  doi       = {10.1016/j.jaci.2014.01.037},
  pages     = {420 -- +},
  year      = {2014},
  abstract  = {Background: Five different G protein-coupled sphingosine-1-phosphate (S1P) receptors (S1P1-S1P5) regulate a variety of physiologic and pathophysiologic processes, including lymphocyte circulation, multiple sclerosis (MS), and cancer. Although B-lymphocyte circulation plays an important role in these processes and is essential for normal immune responses, little is known about S1P receptors in human B cells. Objective: To explore their function and signaling, we studied B-cell lines and primary B cells from control subjects, patients with leukemia, patients with S1P receptor inhibitor-treated MS, and patients with primary immunodeficiencies. Methods: S1P receptor expression was analyzed by using multicolor immunofluorescence microscopy and quantitative PCR. Transwell assays were used to study cell migration. S1P receptor internalization was visualized by means of time-lapse imaging with fluorescent S1P receptor fusion proteins expressed by using lentiviral gene transfer. B-lymphocyte subsets were characterized by means of flow cytometry and immunofluorescence microscopy. Results: Showing that different B-cell populations express different combinations of S1P receptors, we found that S1P1 promotes migration, whereas S1P4 modulates and S1P2 inhibits S1P1 signals. Expression of CD69 in activated B lymphocytes and B cells from patients with chronic lymphocytic leukemia inhibited S1P-induced migration. Studying B-cell lines, normal B lymphocytes, and B cells from patients with primary immunodeficiencies, we identified Bruton tyrosine kinase, beta-arrestin 2, LPS-responsive beige-like anchor protein, dedicator of cytokinesis 8, and Wiskott-Aldrich syndrome protein as critical signaling components downstream of S1P1. Conclusion: Thus S1P receptor signaling regulates human B-cell circulation and might be a factor contributing to the pathology of MS, chronic lymphocytic leukemia, and primary immunodeficiencies.},
  language  = {en}
}
@article{PastukhovSchwalmZangemeisterWittkeetal.2014,
  author    = {Pastukhov, Oleksandr and Schwalm, Stephanie and Zangemeister-Wittke, Uwe and Fabbro, Doriano and Bornancin, Frederic and Japtok, Lukasz and Kleuser, Burkhard and Pfeilschifter, Josef and Huwiler, Andrea},
  title     = {The ceramide kinase inhibitor NVP-231 inhibits breast and lung cancer cell proliferation by inducing M phase arrest and subsequent cell death},
  series = {British journal of pharmacology : journal of The British Pharmacological Society},
  volume    = {171},
  journal   = {British journal of pharmacology : journal of The British Pharmacological Society},
  number    = {24},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0007-1188},
  doi       = {10.1111/bph.12886},
  pages     = {5829 -- 5844},
  year      = {2014},
  abstract  = {Background and PurposeCeramide kinase (CerK) catalyzes the generation of ceramide-1-phosphate which may regulate various cellular functions, including inflammatory reactions and cell growth. Here, we studied the effect of a recently developed CerK inhibitor, NVP-231, on cancer cell proliferation and viability and investigated the role of cell cycle regulators implicated in these responses. Experimental ApproachThe breast and lung cancer cell lines MCF-7 and NCI-H358 were treated with increasing concentrations of NVP-231 and DNA synthesis, colony formation and cell death were determined. Flow cytometry was performed to analyse cell cycle distribution of cells and Western blot analysis was used to detect changes in cell cycle regulator expression and activation. Key ResultsIn both cell lines, NVP-231 concentration-dependently reduced cell viability, DNA synthesis and colony formation. Moreover it induced apoptosis, as measured by increased DNA fragmentation and caspase-3 and caspase-9 cleavage. Cell cycle analysis revealed that NVP-231 decreased the number of cells in S phase and induced M phase arrest with an increased mitotic index, as determined by increased histone H3 phosphorylation. The effect on the cell cycle was even more pronounced when NVP-231 treatment was combined with staurosporine. Finally, overexpression of CerK protected, whereas down-regulation of CerK with siRNA sensitized, cells for staurosporine-induced apoptosis. Conclusions and ImplicationsOur data demonstrate for the first time a crucial role for CerK in the M phase control in cancer cells and suggest its targeted inhibition, using drugs such as NVP-231, in combination with conventional pro-apoptotic chemotherapy.},
  language  = {en}
}
@article{PewznerJungTabazavarehGrassmeetal.2014,
  author    = {Pewzner-Jung, Yael and Tabazavareh, Shaghayegh Tavakoli and Grassme, Heike and Becker, Katrin Anne and Japtok, Lukasz and Steinmann, Joerg and Joseph, Tammar and Lang, Stephan and Tuemmler, Burkhard and Schuchman, Edward H. and Lentsch, Alex B. and Kleuser, Burkhard and Edwards, Michael J. and Futerman, Anthony H. and Gulbins, Erich},
  title     = {Sphingoid long chain bases prevent lung infection by Pseudomonas aeruginosa},
  series = {EMBO molecular medicine},
  volume    = {6},
  journal   = {EMBO molecular medicine},
  number    = {9},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {1757-4676},
  doi       = {10.15252/emmm.201404075},
  pages     = {1205 -- 1214},
  year      = {2014},
  abstract  = {Cystic fibrosis patients and patients with chronic obstructive pulmonary disease, trauma, burn wound, or patients requiring ventilation are susceptible to severe pulmonary infection by Pseudomonas aeruginosa. Physiological innate defense mechanisms against this pathogen, and their alterations in lung diseases, are for the most part unknown. We now demonstrate a role for the sphingoid long chain base, sphingosine, in determining susceptibility to lung infection by P.aeruginosa. Tracheal and bronchial sphingosine levels were significantly reduced in tissues from cystic fibrosis patients and from cystic fibrosis mouse models due to reduced activity of acid ceramidase, which generates sphingosine from ceramide. Inhalation of mice with sphingosine, with a sphingosine analog, FTY720, or with acid ceramidase rescued susceptible mice from infection. Our data suggest that luminal sphingosine in tracheal and bronchial epithelial cells prevents pulmonary P.aeruginosa infection in normal individuals, paving the way for novel therapeutic paradigms based on inhalation of acid ceramidase or of sphingoid long chain bases in lung infection.},
  language  = {en}
}
@article{FayyazHenkelJaptoketal.2014,
  author    = {Fayyaz, Susann and Henkel, Janin and Japtok, Lukasz and Kr{\"a}mer, Stephanie and Damm, Georg and Seehofer, Daniel and P{\"u}schel, Gerhard Paul and Kleuser, Burkhard},
  title     = {Involvement of sphingosine 1-phosphate in palmitate-induced insulin resistance of hepatocytes via the S1P(2) receptor subtype},
  series = {Diabetologia : journal of the European Association for the Study of Diabetes (EASD)},
  volume    = {57},
  journal   = {Diabetologia : journal of the European Association for the Study of Diabetes (EASD)},
  number    = {2},
  publisher = {Springer},
  address   = {New York},
  issn      = {0012-186X},
  doi       = {10.1007/s00125-013-3123-6},
  pages     = {373 -- 382},
  year      = {2014},
  abstract  = {Enhanced plasma levels of NEFA have been shown to induce hepatic insulin resistance, which contributes to the development of type 2 diabetes. Indeed, sphingolipids can be formed via a de novo pathway from the saturated fatty acid palmitate and the amino acid serine. Besides ceramides, sphingosine 1-phosphate (S1P) has been identified as a major bioactive lipid mediator. Therefore, our aim was to investigate the generation and function of S1P in hepatic insulin resistance. The incorporation of palmitate into sphingolipids was performed by rapid-resolution liquid chromatography-MS/MS in primary human and rat hepatocytes. The influence of S1P and the involvement of S1P receptors in hepatic insulin resistance was examined in human and rat hepatocytes, as well as in New Zealand obese (NZO) mice. Palmitate induced an impressive formation of extra- and intracellular S1P in rat and human hepatocytes. An elevation of hepatic S1P levels was observed in NZO mice fed a high-fat diet. Once generated, S1P was able, similarly to palmitate, to counteract insulin signalling. The inhibitory effect of S1P was abolished in the presence of the S1P(2) receptor antagonist JTE-013 both in vitro and in vivo. In agreement with this, the immunomodulator FTY720-phosphate, which binds to all S1P receptors except S1P(2), was not able to inhibit insulin signalling. These data indicate that palmitate is metabolised by hepatocytes to S1P, which acts via stimulation of the S1P(2) receptor to impair insulin signalling. In particular, S1P(2) inhibition could be considered as a novel therapeutic target for the treatment of insulin resistance.},
  language  = {en}
}
@misc{ArltSchwiebsJaptoketal.2014,
  author    = {Arlt, Olga and Schwiebs, Anja and Japtok, Lukasz and Rueger, Katja and Katzy, Elisabeth and Kleuser, Burkhard and Radeke, Heinfried H.},
  title     = {Sphingosine-1-Phosphate modulates dendritic cell function: focus on non-migratory effects in vitro and in vivo},
  series = {Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry and pharmacology},
  volume    = {34},
  journal   = {Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry and pharmacology},
  number    = {1},
  publisher = {Karger},
  address   = {Basel},
  issn      = {1015-8987},
  doi       = {10.1159/000362982},
  pages     = {27 -- 44},
  year      = {2014},
  abstract  = {Dendritic cells (DCs) are the cutting edge in innate and adaptive immunity. The major functions of these antigen presenting cells are the capture, endosomal processing and presentation of antigens, providing them an exclusive ability to provoke adaptive immune responses and to induce and control tolerance. Immature DCs capture and process antigens, migrate towards secondary lymphoid organs where they present antigens to naive T cells in a well synchronized sequence of procedures referred to as maturation. Indeed, recent research indicated that sphingolipids are modulators of essential steps in DC homeostasis. It has been recognized that sphingolipids not only modulate the development of DC subtypes from precursor cells but also influence functional activities of DCs such as antigen capture, and cytokine profiling. Thus, it is not astonishing that sphingolipids and sphingolipid metabolism play a substantial role in inflammatory diseases that are modulated by DCs. Here we highlight the function of sphingosine 1-phosphate (S1P) on DC homeostasis and the role of SIP and SW metabolism in inflammatory diseases.},
  language  = {en}
}
@misc{FayyazJaptokKleuser2014,
  author    = {Fayyaz, Susann and Japtok, Lukasz and Kleuser, Burkhard},
  title     = {Divergent role of sphingosine 1-Phosphate on insulin resistance},
  series = {Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry and pharmacology},
  volume    = {34},
  journal   = {Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry and pharmacology},
  number    = {1},
  publisher = {Karger},
  address   = {Basel},
  issn      = {1015-8987},
  doi       = {10.1159/000362990},
  pages     = {134 -- 147},
  year      = {2014},
  abstract  = {Insulin resistance is a complex metabolic disorder in which insulin-sensitive tissues fail to respond to the physiological action of insulin. There is a strong correlation of insulin resistance and the development of type 2 diabetes both reaching epidemic proportions. Dysfunctional lipid metabolism is a hallmark of insulin resistance and a risk factor for several cardiovascular and metabolic disorders. Numerous studies in humans and rodents have shown that insulin resistance is associated with elevations of non-esterified fatty acids (NEFA) in the plasma. Moreover, bioactive lipid intermediates such as diacylglycerol (DAG) and ceramides appear to accumulate in response to NEFA, which may interact with insulin signaling. However, recent work has also indicated that sphingosine 1-phosphate (S1P), a breakdown product of ceramide, modulate insulin signaling in different cell types. In this review, we summarize the current state of knowledge about S1P and insulin signaling in insulin sensitive cells. A specific focus is put on the action of S1P on hepatocytes, pancreatic beta-cells and skeletal muscle cells. In particular, modulation of S1P-signaling can be considered as a potential therapeutic target for the treatment of insulin resistance and type 2 diabetes.},
  language  = {en}
}
@article{NeuberSchumacherGulbinsetal.2014,
  author    = {Neuber, Corinna and Schumacher, Fabian and Gulbins, Erich and Kleuser, Burkhard},
  title     = {Method to simultaneously determine the sphingosine 1-phosphate breakdown product (2E)-hexadecenal and its fatty acid derivatives using isotope-dilution HPLC-electrospray ionization-quadrupole/time-of-flight mass spectrometry},
  series = {Analytical chemistry},
  volume    = {86},
  journal   = {Analytical chemistry},
  number    = {18},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0003-2700},
  doi       = {10.1021/ac501677y},
  pages     = {9065 -- 9073},
  year      = {2014},
  abstract  = {Sphingosine 1-phosphate (S1P), a bioactive lipid involved in various physiological processes, can be irreversibly degraded by the membrane-bound S1P lyase (S1PL) yielding (2E)-hexadecenal and phosphoethanolamine. It is discussed that (2E)-hexadecenal is further oxidized to (2E)-hexadecenoic acid by the long-chain fatty aldehyde dehydrogenase ALDH3A2 (also known as FALDH) prior to activation via coupling to coenzyme A (CoA). Inhibition or defects in these enzymes, S1PL or FALDH, result in severe immunological disorders or the Sjogren-Larsson syndrome, respectively. Hence, it is of enormous importance to simultaneously determine the S1P breakdown product (2E)-hexadecenal and its fatty acid metabolites in biological samples. However, no method is available so far. Here, we present a sensitive and selective isotope-dilution high performance liquid chromatographyelectrospray ionizationquadrupole/time-of-flight mass spectrometry method for simultaneous quantification of (2E)-hexadecenal and its fatty acid metabolites following derivatization with 2-diphenylacetyl-1,3-indandione-1-hydrazone and 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide. Optimized conditions for sample derivatization, chromatographic separation, and MS/MS detection are presented as well as an extensive method validation. Finally, our method was successfully applied to biological samples. We found that (2E)-hexadecenal is almost quantitatively oxidized to (2E)-hexadecenoic acid, that is further activated as verified by cotreatment of HepG2 cell lysates with (2E)-hexadecenal and the acyl-CoA synthetase inhibitor triacsin C. Moreover, incubations of cell lysates with deuterated (2E)-hexadecenal revealed that no hexadecanoic acid is formed from the aldehyde. Thus, our method provides new insights into the sphingolipid metabolism and will be useful to investigate diseases known for abnormalities in long-chain fatty acid metabolism, e.g., the Sjogren-Larsson syndrome, in more detail.},
  language  = {en}
}