Forschungszentrum Karlsruhe GmbH Technik und Umwelt, Inst. fuer Toxikologie und Genetik. Ergebnisbericht ueber Forschung und Entwicklung 2000

SIGLEAvailable from TIB Hannover: ZA 5141(6538) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Forschungszentrum Karlsruhe GmbH Technik und Umwelt, Inst. fuer Toxikologie und Genetik. Ergebnisbericht ueber Forschung und Entwicklung 2002

SIGLEAvailable from TIB Hannover: ZA 5141(6838) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Forschungszentrum Karlsruhe Technik und Umwelt, Institut fuer Toxikologie und Genetik. Ergebnisbericht ueber Forschung und Entwicklung 1999

Available from TIB Hannover: ZA 5141(6438) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Alkylphosphocholine - eine neue Klasse von Antitumormitteln Untersuchungen zum biochemischen Wirkungsmechanismus

Alkylphosphocholines (APC) represent a new class of anticancer drugs. Although some compounds of this group are already used for tumor therapy (e.g. hexadecylphosphocholine, HePC), not much is known about their molecular mechanisms of anticancerogenic action. HePC is approved for topical treatment of skin metastases of breast cancer, but systemic application is not possible due to gastro-intestinal side effects. Therefore, new APC compounds were synthesized with the aim to reduce the side effects of HePC while preserving the antineoplastic activities. In the present study, the toxic effects of eight new APC compounds on in vitro cell culture systems of human tumor cells were investigated. Three of the new APC showed higher toxic potency than HePC towards HL-60 leukemia cells. The most active compound was R-1-O-phosphocholine-2-N-acetyl-octadecane (R-N-acetyl), with which further studies were mainly carried out. The uptake of R-N-acetyl by tumor cells was slow and dependent on the content of foetal calf serum in the culture media. R-N-acetyl was metabolically stable and degradation was only marginal. The effect of APC on intracellular signal transduction was further specified. It was demonstrated that APC activate the Ras/MAP kinase cascade via a G-protein coupled mechanism. The EGF-receptor was engaged in the activation of the MAP kinase ERK in MDA-MB-468 mammary carcinoma cells. Furthermore, APC induced concentration-dependent a short, transient and receptor-mediated rise in cytosolic free calcium. (orig.)Available from TIB Hannover: ZA 5141(6369) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Links-Rechts-Achsenentwicklung im Kaninchenembryo: Klonierung von Markergenen, Etablierung eines in vitro Kultursystems und Identifizierung des Wachstumsfaktors FGF8 als rechte Determinante

Available from TIB Hannover: ZA 5141(6788) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Die Rolle der Rel/NF-#kappa#B-Transkriptionsfaktoren in der Reifung und Funktion dendritischer Zellen

Available from TIB Hannover: ZA 5141(7006) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Verzoegerung der Signaltransduktionskette des IgE-Rezeptors in Mastzellen als molekulare Basis fuer die antiallergische Wirkung von Glukokortikoiden

Glucocorticoids suppress the expression of Fc#epsilon#RI alpha chain gene by inhibiting its promoter activity. This effect requires de novo protein synthesis and regulatory elements at the Fc#epsilon#RI #alpha#-chain promoter that bind the transcription factors GATA-1, Elf-1, Pu.1 and YY1. The downregulation of the Fc#epsilon#RI #alpha#-chain gene expression correlates with a reduced surface expression of the Fc#epsilon#RI. Furthermore, glucocorticoid treatment promotes inactivation of the lck/yes-related novel (Lyn) Src-like tyrosine kinase, responsible of phosphorylation and activation of the Fc#epsilon#RI, via enhanced phosphorylation of the regulatory tyrosine residue of Lyn. The reduction of surface expressed IgE receptor and the inactivation of Lyn would suppress the signal transduction events originating from the Fc#epsilon#RI and ending up with the activation of the downstream targets ERK1/2. In addition, it has been shown here that glucocorticoids inhibit IgE receptor signalling by enhancing the expression of the MAPK phosphatase MKP-1, which in turn inhibits the activation of ERK1/2. The glucocorticoid-mediated enhancement in MKP-1 expression occurs at the MKP-1 promoter level. This regulation requires the glucocorticoid receptor (GR) dimerisation function and the presence of discrete elements on the promoter proximal sequence, suggesting that it is a direct action of the GR. A crucial role of MKP-1 in glucocorticoid-mediated repression of ERK1/2 phosphorylation was demonstrated in bone marrow derived mast cells from MKP-1-deficient mice. ERK1/2 in these cells are activated by IgE receptor cross-linking or by Stem Cell Factor through the c-kit receptor, and they were no longer inhibited by glucocorticoids, while this was the case in cells from wild-type mice. However, ERK1/2 activity in other cell types such as thymocytes and splenocytes of MKP-1 deficient mice, could still be inhibited by glucocorticoids. These results dmeonstrate that repression of ERK1/2 through MKP-1 is a specific process, that occurs in mast cells but not in other cell populations. (orig.)In der hier vorgestellten Arbeit werden die Wirkung(en) der Glukorkortikoide bei der Hemmung des Fc#epsilon#RI-Signaltransduktionsweges untersucht. Glukokortikoide unterdruecken die Expression des Genes, welches fuer die alpha-Kette des Fc#epsilon#RI kodiert, im Bereich seines Promoters. Dieser Effekt benoetigt neue Proteinsynthese und regulatorische Elemente im Promoter des Genes fuer die Fc#epsilon#RI-alpha-Kette, an welche die Transkriptionsfaktoren GATA-1, Elf-1, PU.1 und YY1 binden koennen. Die Verringerung der Expression des Genes, welches fuer die Fc#epsilon#RI-alpha-Kette kodiert, korreliert mit einer verringerten Oberflaechenexpression des gesamten Fc#epsilon#RI-Komplexes. Darueber hinaus foerdert die Behandlung mit Glukokortikoiden die Inaktivierung der mit lck/yes-verwandten neuen Src-aehnlichen Tyrosinkinase Lyn, welche fuer die Phosphorylierung und Aktivierung von Fc#epsilon#RI verantwortlich ist, mittels einer verstaerkten Phosphorylierung der regulatorischen Tyrosinreste von Lyn. Diese Reduktion der Oberflaechenexpression des IgE-Rezeptors (Fc#epsilon#RI) und Inaktivierung von Lyn koennen die Signaltransduktionsereignisse unterdruecken, die vom Fc#epsilon#RI kommen und mit der Aktivierung des weiter unten in der Signaltransduktionskaskade befindlichen Zielmolekuels ERK1/2 enden. Zusaetzlich konnte in dieser Arbeit gezeigt werden, dass Glukokortikoide den durch den IgE-Rezeptor aktivierten Signaltransduktionsweg ueber eine Verstaerkung der Expression der MAPK-Phosphatase MKP-1, welche ihrerseits die Aktivierung von ERK1/2 hemmt, vermindern koennen. Die ueber Glukokortikoide vermittelte Verstaerkung der Aktivitaet von MKP-1 findet am Promoter von MKP-1 statt. Fuer diese Regulation ist sowohl eine Dimerisation des Glukokortikoidrezeptors (GR) notwendig, als auch das Vorhandensein bestimmter Elemente an der Promotorsequenz. Dies weist darauf hin, dass es sich um eine direkte Aktion des GR handelt. Gezeigt werden konnte eine entscheidende Rolle von MKP-1 bei der Glukokortikoid-vermittelten Unterdrueckung der ERK1/2-Phosphorylierung in Mastzellen, die aus primaeren Knochenmarkszellen von MKP-1-defizienten Maeusen stammen. ERK1/2 werden in diesen Zellen durch die Kreuzreaktion des IgE-Rezeptors oder durch den Stammzellfaktor, welcher ueber den c-Kit-Rezeptor wirkt, aktiviert und nicht laenger durch Glukokortikoide gehemmt, wie dies in Zellen von Wildtyp-Maeusen der Fall ist. Allerdings konnte die Aktivitaet von ERK1/2 in anderen Zelltypen wie Thymozyten und Splenozyten von MKP-1-defizienten Maeusen immer noch durch Glukokortikoide gehemmt werden. Diese Ergebnisse zeigen, dass die Repression von ERK1/2 durch MKP-1 ein spezifischer Prozess ist, welcher in Mastzellen, aber nicht in anderen Zellpopulationen stattfindet. (orig.)SIGLEAvailable from TIB Hannover: ZA 5141(6857) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Hyaluronate induces cytokines in stromal cells which support hematopoiesis

SIGLEAvailable from TIB Hannover: ZA 5141(6624) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Die Rolle des Homoeoboxgens goosecoid in der mesodermalen Differenzierung von embryonalen Stammzellen und der Teratokarzinomazellinie P19 der Maus

The homeobox gene goosecoid, originally identified in Xenopus, is expressed in the organizer or its equivalent during gastrulation in the frog, chick, zebrafish and mouse. To investigate the role of goosecoid in mouse development, embryonic stem cells were generated that stably overexpress the murine homologue of goosecoid under the control of the ubiquitin-promotor. These clones revealed a mesenchymal-like morphology distinct from wildtype ES-cells without any further differentiation steps. Vimentin, a marker gene for mesenchymal cells, is expressed in these cell clones. The morphological changes of these cells did not correlate with a reduction of the expression level of the cell adhesion molecule E-Cadherin. The goosecoid ES-clones express important organizer-specific genes like the neural inducers chordin and follistatin, the homebox gene Otx2 and the forkhead gene HNF3#beta#. Surprisingly, lim-1-mRA as well as the expression of gastrulation-associated gene Brachyury could not be detected in these cells. (orig.)Available from TIB Hannover: ZA 5141(6382) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Struktur und subzellulaere Lokalisierung des Androgenrezeptors mit verlaengerter Glutaminsequenz aus Patienten mit spinaler und bulbaerer Muskelatrophie

Spinal and bulbar muscular atrophy (SBMA; also known as Kennedy's disease) is a neurodegenerative disease caused by the amplification of a CAG-triplet sequence in the coding region of the androgen receptor (AR) gene. The mutated receptor is not only expressed in regions of the brain that are affected by the disease but also in unaffected areas. Therefore cell-type specific factors must be involved in the pathogenic action of the mutated receptor. In this study AR proteins only differing in the length of their glutamine (Q) sequence were studied (Q1, Q22 and Q77). Their ability to bind factors from mouse brain extracts and their physicochemical properties were analysed. The aim of the work was to characterise properties that are unique for the receptor with a prolonged glutamine sequence. An interaction study using immobilised glutamine sequences was employed to identify factors that interact with the AR in a sequence specific manner. Tubulin was found to interact exclusively with the glutamine sequence of nonpathogenic length (22 glutamine residues). The specificity of the interaction was confirmed in a cosedimentation assay. The AR with the nonpathogenic sequence length of 22 glutamine residues (ARQ22) but not the AR with a pathogenic sequence length of 77 glutamine residues (ARQ77) coprecipitated with microtubules. (orig.)Available from TIB Hannover: ZA 5141(6494) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman