@article{LiedertRoentgenSchinkeetal.2014, author = {Liedert, Astrid and R{\"o}ntgen, Viktoria and Schinke, Thorsten and Benisch, Peggy and Ebert, Regina and Jakob, Franz and Klein-Hitpass, Ludger and Lennerz, Jochen K. and Amling, Michael and Ignatius, Anita}, title = {Osteoblast-Specific Krm2 Overexpression and Lrp5 Deficiency Have Different Effects on Fracture Healing in Mice}, series = {PLOS ONE}, volume = {9}, journal = {PLOS ONE}, number = {7}, issn = {1932-6203}, doi = {10.1371/journal.pone.0103250}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-115782}, pages = {e103250}, year = {2014}, abstract = {The canonical Wnt/beta-catenin pathway plays a key role in the regulation of bone remodeling in mice and humans. Two transmembrane proteins that are involved in decreasing the activity of this pathway by binding to extracellular antagonists, such as Dickkopf 1 (Dkk1), are the low-density lipoprotein receptor related protein 5 (Lrp5) and Kremen 2 (Krm2). Lrp 5 deficiency (Lrp5(-/-)) as well as osteoblast-specific overexpression of Krm2 in mice (Col1a1-Krm2) result in severe osteoporosis occurring at young age. In this study, we analyzed the influence of Lrp5 deficiency and osteoblast-specific overexpression of Krm2 on fracture healing in mice using flexible and semi-rigid fracture fixation. We demonstrated that fracture healing was highly impaired in both mouse genotypes, but that impairment was more severe in Col1a1-Krm2 than in Lrp5(-/-) mice and particularly evident in mice in which the more flexible fixation was used. Bone formation was more reduced in Col1a1-Krm2 than in Lrp5(-/-) mice, whereas osteoclast number was similarly increased in both genotypes in comparison with wild-type mice. Using microarray analysis we identified reduced expression of genes mainly involved in osteogenesis that seemed to be responsible for the observed stronger impairment of healing in Col1a1-Krm2 mice. In line with these findings, we detected decreased expression of sphingomyelin phosphodiesterase 3 (Smpd3) and less active beta-catenin in the calli of Col1a1-Krm2 mice. Since Krm2 seems to play a significant role in regulating bone formation during fracture healing, antagonizing KRM2 might be a therapeutic option to improve fracture healing under compromised conditions, such as osteoporosis.}, language = {en} } @article{SanzMorenoFuhrmannWolfetal.2014, author = {Sanz-Moreno, Adrian and Fuhrmann, David and Wolf, Elmar and von Eyss, Bj{\"o}rn and Eilers, Martin and Els{\"a}sser, Hans-Peter}, title = {Miz1 Deficiency in the Mammary Gland Causes a Lactation Defect by Attenuated Stat5 Expression and Phosphorylation}, series = {PLOS ONE}, volume = {9}, journal = {PLOS ONE}, number = {2}, doi = {10.1371/journal.pone.0089187}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-117286}, pages = {e89187}, year = {2014}, abstract = {Miz1 is a zinc finger transcription factor with an N-terminal POZ domain. Complexes with Myc, Bcl-6 or Gfi-1 repress expression of genes like Cdkn2b (p15(Ink4)) or Cd-kn1a (p21(Cip1)). The role of Miz1 in normal mammary gland development has not been addressed so far. Conditional knockout of the Miz1 POZ domain in luminal cells during pregnancy caused a lactation defect with a transient reduction of glandular tissue, reduced proliferation and attenuated differentiation. This was recapitulated in vitro using mouse mammary gland derived HC11 cells. Further analysis revealed decreased Stat5 activity in Miz1 Delta POZ mammary glands and an attenuated expression of Stat5 targets. Gene expression of the Prolactin receptor (PrlR) and ErbB4, both critical for Stat5 phosphorylation (pStat5) or pStat5 nuclear translocation, was decreased in Miz1 Delta POZ females. Microarray, ChIP-Seq and gene set enrichment analysis revealed a down-regulation of Miz1 target genes being involved in vesicular transport processes. Our data suggest that deranged intracellular transport and localization of PrlR and ErbB4 disrupt the Stat5 signalling pathway in mutant glands and cause the observed lactation phenotype.}, language = {en} } @phdthesis{Hovhanyan2014, author = {Hovhanyan, Anna}, title = {Functional analyses of Mushroom body miniature (Mbm) in growth and proliferation of neural progenitor cells in the central brain of Drosophila melanogaster}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-91303}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2014}, abstract = {Zellwachstum und Zellteilung stellen zwei miteinander verkn{\"u}pfte Prozesse dar, die dennoch grunds{\"a}tzlich voneinander zu unterscheiden sind. Die Wiederaufnahme der Proliferation von neuralen Vorl{\"a}uferzellen (Neuroblasten) im Zentralhirn von Drosophila nach der sp{\"a}t-embryonalen Ruhephase erfordert zun{\"a}chst Zellwachstum. Der Erhalt der regul{\"a}ren Zellgr{\"o}ße ist eine wichtige Voraussetzung f{\"u}r die kontinuierliche Proliferation der Neuroblasten {\"u}ber die gesamte larvale Entwicklungsphase. Neben extrinsischen Ern{\"a}hrungssignalen ist f{\"u}r das Zellwachstum eine kontinuierliche Versorgung mit funktionellen Ribosomen notwendig, damit die Proteinsynthese aufrechterhalten werden kann. Mutationen im mushroom body miniature (mbm) Gen wurden {\"u}ber einen genetischen Screen nach strukturellen Gehirnmutanten identifiziert. Der Schwerpunkt dieser Arbeit lag in der funktionellen Charakterisierung des Mbm Proteins als neues nukleol{\"a}res Protein und damit seiner m{\"o}glichen Beteiligung in der Ribosomenbiogenese. Der Vergleich der relativen Expressionslevel von Mbm und anderen nuklearen Proteinen in verschiedenen Zelltypen zeigte eine verst{\"a}rkte Expression von Mbm in der fibrill{\"a}ren Komponente des Nukleolus von Neuroblasten. Diese Beobachtung legte die Vermutung nahe, dass in Neuroblasten neben generell ben{\"o}tigten Faktoren der Ribosomenbiogenese auch Zelltyp-spezifische Faktoren existieren. Mutationen in mbm verursachen Proliferationsdefekte von Neuroblasten, wirken sich jedoch nicht auf deren Zellpolarit{\"a}t, die Orientierung der mitotischen Spindel oder die Asymmetrie der Zellteilung aus. Stattdessen wurde eine Reduktion der Zellgr{\"o}ße beobachtet, was im Einklang mit einer Beeintr{\"a}chtigung der Ribosomenbiogenese steht. Insbesondere f{\"u}hrt der Verlust der Mbm Funktion zu einer Retention der kleinen ribosomalen Untereinheit im Nukleolus, was eine verminderte Proteinsynthese zur Folge hat. Interessanterweise wurden St{\"o}rungen der Ribosomenbiogenese nur in den Neuroblasten beobachtet. Zudem ist Mbm offensichtlich nicht erforderlich, um Wachstum oder die Proliferation von Zellen der Fl{\"u}gelimginalscheibe und S2-Zellen zu steuern, was wiederum daf{\"u}r spricht, dass Mbm eine Neuroblasten-spezifische Funktion erf{\"u}llt. Dar{\"u}ber hinaus wurden die transkriptionelle Regulation des mbm-Gens und die funktionelle Bedeutung von posttranslationalen Modifikationen analysiert. Mbm Transkription wird von dMyc reguliert. Ein gemeinsames Merkmal von dMyc Zielgenen ist das Vorhandensein einer konservierten „E-Box"-Sequenz in deren Promotorregionen. In der Umgebung der mbm-Transkriptionsstartstelle befinden sich zwei „E-Box"-Motive. Mit Hilfe von Genreporteranalysen konnte nachgewiesen werden, dass nur eine von ihnen die dMyc-abh{\"a}ngige Transkription vermittelt. Die dMyc-abh{\"a}ngige Expression von Mbm konnte auch in Neuroblasten verifiziert werden. Auf posttranslationaler Ebene wird Mbm durch die Proteinkinase CK2 phosphoryliert. In der C-terminalen H{\"a}lfte des Mbm Proteins wurden in zwei Clustern mit einer Abfolge von sauren Aminos{\"a}uren sechs Serin- und Threoninreste als CK2- Phosphorylierungsstellen identifiziert. Eine Mutationsanalyse dieser Stellen best{\"a}tigte deren Bedeutung f{\"u}r die Mbm Funktion in vivo. Weiterhin ergaben sich Evidenzen, dass die Mbm-Lokalisierung durch die CK2-vermittelte Phosphorylierung gesteuert wird. Obwohl die genaue molekulare Funktion von Mbm in der Ribosomenbiogenese noch im Unklaren ist, unterstreichen die Ergebnisse dieser Studie die besondere Rolle von Mbm in der Ribosomenbiogenese von Neuroblasten um Zellwachstum und Proliferation zu regulieren.}, subject = {Taufliege}, language = {en} } @article{BensaadFavaroLewisetal.2014, author = {Bensaad, Karim and Favaro, Elena and Lewis, Caroline A. and Peck, Barrie and Lord, Simon and Collins, Jennifer M. and Pinnick, Katherine E. and Wigfield, Simon and Buffa, Francesca M. and Li, Ji-Liang and Zhang, Qifeng and Wakelam, Michael J. O. and Karpe, Fredrik and Schulze, Almut and Harris, Adrian L.}, title = {Fatty Acid Uptake and Lipid Storage Induced by HIF-1 alpha Contribute to Cell Growth and Survival after Hypoxia-Reoxygenation}, series = {Cell Reports}, volume = {9}, journal = {Cell Reports}, number = {1}, issn = {2211-1247}, doi = {10.1016/j.celrep.2014.08.056}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-115162}, pages = {349-365}, year = {2014}, abstract = {An in vivo model of antiangiogenic therapy allowed us to identify genes upregulated by bevacizumab treatment, including Fatty Acid Binding Protein 3 (FABP3) and FABP7, both of which are involved in fatty acid uptake. In vitro, both were induced by hypoxia in a hypoxia-inducible factor-1 alpha (HIF-1 alpha)-dependent manner. There was a significant lipid droplet (LD) accumulation in hypoxia that was time and O-2 concentration dependent. Knockdown of endogenous expression of FABP3, FABP7, or Adipophilin (an essential LD structural component) significantly impaired LD formation under hypoxia. We showed that LD accumulation is due to FABP3/7-dependent fatty acid uptake while de novo fatty acid synthesis is repressed in hypoxia. We also showed that ATP production occurs via beta-oxidation or glycogen degradation in a cell-type-dependent manner in hypoxia-reoxygenation. Finally, inhibition of lipid storage reduced protection against reactive oxygen species toxicity, decreased the survival of cells subjected to hypoxia-reoxygenation in vitro, and strongly impaired tumorigenesis in vivo.}, language = {en} } @article{RathBrandlHilleretal.2014, author = {Rath, Subha N. and Brandl, Andreas and Hiller, Daniel and Hoppe, Alexander and Gbureck, Uwe and Horch, Raymund E. and Boccaccini, Aldo R. and Kneser, Ulrich}, title = {Bioactive Copper-Doped Glass Scaffolds Can Stimulate Endothelial Cells in Co-Culture in Combination with Mesenchymal Stem Cells}, series = {PLOS ONE}, volume = {9}, journal = {PLOS ONE}, number = {12}, issn = {1932-6203}, doi = {10.1371/journal.pone.0113319}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-114339}, year = {2014}, abstract = {Bioactive glass (BG) scaffolds are being investigated for bone tissue engineering applications because of their osteoconductive and angiogenic nature. However, to increase the in vivo performance of the scaffold, including enhancing the angiogenetic growth into the scaffolds, some researchers use different modifications of the scaffold including addition of inorganic ionic components to the basic BG composition. In this study, we investigated the in vitro biocompatibility and bioactivity of Cu2+-doped BG derived scaffolds in either BMSC (bone-marrow derived mesenchymal stem cells)-only culture or co-culture of BMSC and human dermal microvascular endothelial cells (HDMEC). In BMSC-only culture, cells were seeded either directly on the scaffolds (3D or direct culture) or were exposed to ionic dissolution products of the BG scaffolds, kept in permeable cell culture inserts (2D or indirect culture). Though we did not observe any direct osteoinduction of BMSCs by alkaline phosphatase (ALP) assay or by PCR, there was increased vascular endothelial growth factor (VEGF) expression, observed by PCR and ELISA assays. Additionally, the scaffolds showed no toxicity to BMSCs and there were healthy live cells found throughout the scaffold. To analyze further the reasons behind the increased VEGF expression and to exploit the benefits of the finding, we used the indirect method with HDMECs in culture plastic and Cu2+-doped BG scaffolds with or without BMSCs in cell culture inserts. There was clear observation of increased endothelial markers by both FACS analysis and acetylated LDL (acLDL) uptake assay. Only in presence of Cu2+-doped BG scaffolds with BMSCs, a high VEGF secretion was demonstrated by ELISA; and typical tubular structures were observed in culture plastics. We conclude that Cu2+-doped BG scaffolds release Cu2+, which in turn act on BMSCs to secrete VEGF. This result is of significance for the application of BG scaffolds in bone tissue engineering approaches.}, language = {en} }