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Frankfurt am Main, Germany

Pufahl L.,Goethe University Frankfurt | Katryniok C.,Goethe University Frankfurt | Schnur N.,Goethe University Frankfurt | Sorg B.L.,Goethe University Frankfurt | And 3 more authors.
Journal of Cellular and Molecular Medicine | Year: 2012

The 5-lipoxygenase (5-LO) is the key enzyme in the formation of leukotrienes. We have previously shown that the histone deacetylase (HDAC) inhibitor trichostatin A (TSA) activates 5-LO transcription via recruitment of Sp1, Sp3 and RNA polymerase II to the proximal promoter. To identify the HDACs involved in the regulation of 5-LO promoter activity isoform-specific HDAC inhibitors were applied. 5-LO promoter activity and mRNA expression were up-regulated by the class I HDAC inhibitors apicidin and MS-275 but not by class II inhibitors. Knockdown of HDAC 1, 2 and 3 revealed that HDAC2 and HDAC3 but not HDAC1 is involved in the up-regulation of 5-LO mRNA expression. To analyse the chromatin modifications at the 5-LO promoter associated with HDAC inhibition, the time course of 5-LO mRNA induction by trichostatin A was investigated and the concomitant changes in histone modifications at the 5-LO promoter in HL-60, U937 and Mono Mac6 cells were determined. Chromatin immunoprecipitation analysis revealed that trichostatin A increases acetylation of histones H3 and H4 at the 5-LO core promoter in HL-60 and U937 cells whereas no significant changes were observed in Mono Mac6 cells. The appearance of H3 and H4 acetylation preceded the 5-LO mRNA induction whereas in all three cell lines, induction of 5-LO mRNA expression correlated with histone H3 lysine 4 trimethylation (H3K4me3), a marker for transcriptional activity of gene promoters. © 2011 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd. Source


Ochs M.J.,Goethe University Frankfurt | Sorg B.L.,Goethe University Frankfurt | Pufahl L.,Goethe University Frankfurt | Grez M.,Georg Speyer Haus | And 2 more authors.
PLoS ONE | Year: 2012

5-Lipoxygenase (5-LO) catalyzes the two initial steps in the biosynthesis of leukotrienes (LT), a group of inflammatory lipid mediators derived from arachidonic acid. Here, we investigated the regulation of 5-LO mRNA expression by alternative splicing and nonsense-mediated mRNA decay (NMD). In the present study, we report the identification of 2 truncated transcripts and 4 novel 5-LO splice variants containing premature termination codons (PTC). The characterization of one of the splice variants, 5-LOΔ3, revealed that it is a target for NMD since knockdown of the NMD factors UPF1, UPF2 and UPF3b in the human monocytic cell line Mono Mac 6 (MM6) altered the expression of 5-LOΔ3 mRNA up to 2-fold in a cell differentiation-dependent manner suggesting that cell differentiation alters the composition or function of the NMD complex. In contrast, the mature 5-LO mRNA transcript was not affected by UPF knockdown. Thus, the data suggest that the coupling of alternative splicing and NMD is involved in the regulation of 5-LO gene expression. © 2012 Ochs et al. Source


Preu E.,University of Hamburg | Muik A.,Georg Speyer Haus | Muik A.,Innsbruck Medical University | Weber K.,University of Hamburg | And 3 more authors.
Journal of Molecular Medicine | Year: 2011

Suicide gene therapy is a promising concept in oncology. We have recently introduced a novel suicide gene, TK.007, which was shown to excel established herpes simplex virus thymidine kinase (HSVtk) variants when used for donor-lymphocyte modification in adoptive immunotherapy models. Here, the potential of TK.007 in killing cancer cells was studied. Initially, we transduced tumour cell lines derived from different neoplasias (glioblastoma, melanoma, lung cancer, colon cancer) with lentiviral LeGO vectors encoding TK.007 or the splice-corrected (sc)HSVtk together with an eGFP/Neo-marker. Based on direct in vitro comparison, we found that TK.007 facilitates more efficient tumour cell killing at significantly lower ganciclovir doses in all tumour cell lines tested. Also, using different readout systems, we found a significantly stronger bystander effect of TK.007 as compared to scHSVtk. Importantly, in vitro data were confirmed in vivo using a subcutaneous G62 glioblastoma model in NOD/SCID mice. In mice transplanted with scHSVtk-positive tumours, treatment with low (10 mg/kg) or standard (50 mg/kg) ganciclovir doses resulted only in short-term growth inhibition or transient tumour remission, respectively. In striking contrast, in the TK.007 group, all animals achieved continuous complete remission after both standard and low-dose ganciclovir. Finally, a substantial bystander effect for TK.007 was also confirmed with the G62 model in vivo, where significantly prolonged survival for mice bearing tumours containing only 10% or 50% TK.007-expressing cells was observed. In summary, our data indicate strongly improved anti-tumour activity of TK.007 as compared to conventional HSVtk. We therefore suppose that TK.007 is an excellent candidate for cancer suicide gene therapy. © 2011 Springer-Verlag. Source


Smeenk L.,Radboud University Nijmegen | van Heeringen S.J.,Radboud University Nijmegen | Koeppel M.,Radboud University Nijmegen | Gilbert B.,Georg Speyer Haus | And 3 more authors.
PLoS ONE | Year: 2011

The tumor suppressor p53 plays a crucial role in cellular growth control inducing a plethora of different response pathways. The molecular mechanisms that discriminate between the distinct p53-responses have remained largely elusive. Here, we have analyzed the p53-regulated pathways induced by Actinomycin D and Etoposide treatment resulting in more growth arrested versus apoptotic cells respectively. We found that the genome-wide p53 DNA-binding patterns are almost identical upon both treatments notwithstanding transcriptional differences that we observed in global transcriptome analysis. To assess the role of post-translational modifications in target gene choice and activation we investigated the genome-wide level of phosphorylation of Serine 46 of p53 bound to DNA (p53-pS46) and of Serine 15 (p53-pS15). Interestingly, the extent of S46 phosphorylation of p53 bound to DNA is considerably higher in cells directed towards apoptosis while the degree of phosphorylation at S15 remains highly similar. Moreover, our data suggest that following different chemotherapeutical treatments, the amount of chromatin-associated p53 phosphorylated at S46 but not at pS15 is higher on certain apoptosis related target genes. Our data provide evidence that cell fate decisions are not made primarily on the level of general p53 DNA-binding and that post-translationally modified p53 can have distinct DNA-binding characteristics. © 2011 Smeenk et al. Source


Deutsch G.B.,Goethe University Frankfurt | Zielonka E.M.,University of Strasbourg | Zielonka E.M.,Genome Institute of Singapore | Coutandin D.,Goethe University Frankfurt | And 19 more authors.
Cell | Year: 2011

TAp63α, a homolog of the p53 tumor suppressor, is a quality control factor in the female germline. Remarkably, already undamaged oocytes express high levels of the protein, suggesting that TAp63α's activity is under tight control of an inhibitory mechanism. Biochemical studies have proposed that inhibition requires the C-terminal transactivation inhibitory domain. However, the structural mechanism of TAp63α inhibition remains unknown. Here, we show that TAp63α is kept in an inactive dimeric state. We reveal that relief of inhibition leads to tetramer formation with ∼20-fold higher DNA affinity. In vivo, phosphorylation-triggered tetramerization of TAp63α is not reversible by dephosphorylation. Furthermore, we show that a helix in the oligomerization domain of p63 is crucial for tetramer stabilization and competes with the transactivation domain for the same binding site. Our results demonstrate how TAp63α is inhibited by complex domain-domain interactions that provide the basis for regulating quality control in oocytes. © 2011 Elsevier Inc. Source

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