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  • 1
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 23, No. 23 ( 2003-09-10), p. 8330-8339
    Abstract: Gephyrin is an essential component of the postsynaptic cortical protein network of inhibitory synapses. Gephyrin-based scaffolds participate in the assembly as well as the dynamics of receptor clusters by connecting the cytoplasmic domains of glycine and GABA A receptor polypeptides to two cytoskeletal systems, microtubules and microfilaments. Although there is evidence for a physical linkage between gephyrin and microtubules, the interaction between gephyrin and microfilaments is not well understood so far. Here, we show that neuronal gephyrin interacts directly with key regulators of microfilament dynamics, profilin I and neuronal profilin IIa, and with microfilament adaptors of the mammalian enabled (Mena)/vasodilator stimulated phosphoprotein (VASP) family, including neuronal Mena. Profilin and Mena/VASP coprecipitate with gephyrin from tissue and cells, and complex formation requires the E-domain of gephyrin, not the proline-rich central domain. Consequently, gephyrin is not a ligand for the proline-binding motif of profilins, as suspected previously. Instead, it competes with G-actin and phospholipids for the same binding site on profilin. Gephyrin, profilin, and Mena/VASP colocalize at synapses of rat spinal cord and cultivated neurons and in gephyrin clusters expressed in transfected cells. Thus, Mena/VASP and profilin can contribute to the postulated linkage between receptors, gephyrin scaffolds, and the microfilament system and may regulate the microfilament-dependent receptor packing density and dynamics at inhibitory synapses.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2003
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  • 2
    Online Resource
    Online Resource
    Society for Neuroscience ; 2005
    In:  The Journal of Neuroscience Vol. 25, No. 2 ( 2005-01-12), p. 479-487
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 25, No. 2 ( 2005-01-12), p. 479-487
    Abstract: Leucine-rich repeat and PDZ [postsynaptic density-95 (PSD-95)/Discs large/zona occludens-1] domain proteins such as scribble and Densin-180 have been implicated in the establishment of cell-cell contacts. Here, we show that Densin-180, which has been identified as a constituent of the postsynaptic density in excitatory synapses interacts with the postsynaptic scaffold protein shank (shank1-3). The interaction involves a two-point attachment of the C-terminal region of Densin-180 with the Src homology 3 domain and the N-terminal part of the proline-rich region of shank proteins. The N-terminal leucine-rich repeat region, which is not involved in binding shank, targets Densin-180 to the plasma membrane in transfected cells and to the basolateral membrane of epithelial cells. Nevertheless, coexpression of shank leads to a redirection of Densin-180 into intracellular clusters. In cultured hippocampal neurons, Densin-180 overexpression induces excessive branching of neuronal dendrites, which occurs at the expense of clusters for the postsynaptic marker PSD-95. Coexpression of shank3 abrogates branch formation and targets Densin-180 into postsynaptic clusters instead. Shank blocks binding of δ-catenin but not αCaM kinase II to Densin-180; because δ-catenin has been shown to induce branching and neurite formation, our data suggest a mechanism where shank could block the activation of a Densin-180-dependent signaling pathway by δ-catenin.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2005
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  • 3
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 71, No. 8_Supplement ( 2011-04-15), p. 4503-4503
    Abstract: Hypoxia is a hallmark of solid tumors and is associated with local invasion, metastatic spread and resistance to radio- as well as chemotherapy (Vaupel et al., 2004). Furthermore, hypoxia constitutes an independent negative prognostic factor in a diverse range of malignant tumors (Harris, 2002; Vaupel et al., 2004). The cellular adaptation to hypoxia is mediated by a heterodimeric transcription factor hypoxia inducible factor-1 (HIF1). HIF-1α, one subunit of HIF, is constitutively degraded under normoxic conditions, but is stabilized and activated in hypoxic regions of tumors. Nuclear activated HIF-1 controls the expression of & gt;100 genes involved in cellular energy metabolism, neoangiogenesis, anti-apoptotic and pro-proliferative mechanisms promoting invasion and metastasis. It was our hypothesis that small-molecule inhibitor that prevent stabilization and activation of HIF-1 may act as valuable novel cancer therapeutics. Recently, we identified BAY 87-2243 as a small molecule inhibitor of hypoxia-induced HIF-1 activation that specifically suppressed hypoxia-induced HIF-1α stabilization and expression of HIF target genes. Here we present preclinical anti-tumor efficacy of BAY 87-2243 in several xenografts, both as single agent and in combination with standards treatments. BAY 87-2243 dosed orally as single agent demonstrated moderate to high tumor growth inhibition in several subcutaneous tumor models of various histological type such as prostate carcinoma, lung carcinoma, neuroblastoma, colorectal and mammary carcinomas. BAY 87-2243 dosed continuously in combination with the anti-angiogenic agent bevacizumab produced long-term tumor growth control or tumor stasis of either small or large established subcutaneous and orthotopic lung carcinoma xenografts (NSCLC H460 model). In an orthotopic pancreatic carcinoma model (DAN-G) a combination of BAY 87-2243 and gemcitabine resulted in a synergistic improvement of the median survival as compared to either agents alone (p=0.0004). In general, BAY 87-2243 was well tolerated in mice without any significant body weight loss. These promising preclinical results suggest that inhibition of HIF-1 by BAY 87-2243 is an innovative approach to cancer therapy with the potential to overcome hypoxia/HIF-induced tumor resistance mechanisms. Harris AL (2002) Hypoxia-a key regulatory factor in tumor growth. Nat Rev Cancer 2: 38-47 Vaupel P, Mayer A, Hockel M (2004) Tumor hypoxia and malignant progression. Methods Enzymol 381:335-354 Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4503. doi:10.1158/1538-7445.AM2011-4503
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2011
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  • 4
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 71, No. 8_Supplement ( 2011-04-15), p. LB-147-LB-147
    Abstract: BAY 87–2243 is a novel small molecule inhibitor of hypoxia inducible factor-1α (HIF-1α) activity. Preclinical studies with BAY 87–2243 in a number of murine tumor models showed moderate to high tumor growth inhibition. The present study describes a non-invasive positron emission tomographic (PET) imaging method that monitors early therapeutic efficacy of this drug. To identify optimal tracer(s) for monitoring BAY 87–2243 anti-tumor activity, female nude mice were implanted on both scapulae with either 3.5×106 human non-small cell lung cancer (H460) or 2×106 human prostate cancer cells (PC3). Both are growth-inhibited by BAY 87–2243. Xenografts were grown to 200 mm3 over 10 days. Four PET tracers were assessed for uptake into tumor xenografts: 18F-FDG, 18F-FPP(RGD)2, 18F-FLT and 18F-FAZA. Tracers were injected via the tail vein. After pre-scan, BAY 87–2243 was orally administered, daily at 9mg/kg to 7 days. Tracer uptake was examined 1 and 3 day(s) after initial administration. Each treatment group for each PET tracer tested consisted of 6 tumors in 3 animals. At each imaging time point, RNA from BAY 87–2243-treated and vehicle-treated H460 tumor xenografts (3 additional animals each) was isolated. HIF target genes were quantified by Real-Time polymerase chain (RT-PCR) reaction. For both 18F-FDG and 18F-FPP(RGD)2, uptake was not significantly altered. However, 18F-FAZA tumor uptake (%ID mean/g) declined by 55–70% (1.21 ± 0.10 %ID/g to 0.35 ± 0.1 %ID/g, n=6, vehicle vs. treatment) in both H460 (p & lt;0.001) and PC3 (p & lt;0.05) models at both 1 and 3 days after drug administration. The decline occurred before any significant difference in tumor volume between drug- and vehicle-treated animals was observed, thus suggesting that decline in 18F-FAZA uptake reflected early changes in tumor biochemistry. A similar observation was noted for 18F-FLT in the H460 model, although the decline was less pronounced (30%; p & lt;0.05 for all time-points). Analysis of HIF target gene expression by RT-PCR revealed that BAY 87–2243 reduced expression of the hypoxia regulated genes CA IX and ANGPTL4 by 99 % and 93 % respectively (p & lt;0.001 for both) which corresponds with reduced 18F-FAZA uptake upon drug treatment. Reduced 18F-FLT uptake was not accompanied by reduced expression of TK1. Expression level of genes associated with glucose metabolism was heterogeneous and did not fully match with unchanged 18F-FDG uptake: GLUT-1 expression was unchanged while HK-2 decreased by 75 % (p & lt;0.01). We detected low ITGB3 expression in untreated xenografts but were unable to detect transcripts after BAY 87–2243 treatment. This findings may explain the lack of change in 18F-FPP(RGD)2 uptake. In conclusion, our pilot studies suggest the suitability of 18F-FAZA-PET to monitor the efficacy of anti-cancer agents targeting the HIF pathway (e.g. BAY 87–2243) as an early PD marker prior to changes in tumor volume Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-147. doi:10.1158/1538-7445.AM2011-LB-147
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2011
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  • 5
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 71, No. 8_Supplement ( 2011-04-15), p. 4509-4509
    Abstract: The development of resistance against radio- or chemotherapy is one of the main causes for relapse after treatment and ultimately cancer progression. Local hypoxia within tumors is associated with radio- and chemoresistance as well as aggressive tumor growth and invasion (Vaupel et al., 2004). The transcription factor HIF-1α (hypoxia-inducible factor) is stabilized under low oxygen tension and heterodimerizes with HIF-1ß to regulate the expression of a plethora of genes involved in cellular energy metabolism, neoangiogenesis, anti-apoptotic and pro-proliferative mechanisms promoting tumor progression and metastasis (Calzada et al. 2007). Because hypoxia-induced upregulation of HIF-1α appears to be of pivotal importance in tumor resistance mechanisms during cancer treatment, we screened for inhibitors of hypoxia-induced HIF-1 activation. A HCT116 cell line containing 4X-hypoxia response element-luciferase reporter was used in high-throughput screening of small molecule inhibitors under hypoxic condition (1% O2). Lead optimization resulted in the identification of BAY 87-2243, a highly selective and potent inhibitor of hypoxia-induced HIF-1α stabilization and activation. In vitro characterization showed that BAY 87-2243 specifically suppressed HIF-1 regulated target genes as assayed by qPCR. Analyses addressing the mode of action revealed that BAY 87-2243 acts upstream of VHL and PHD because the compound did not suppress HIF-1α protein stabilization and HIF target gene expression either in the presence of a PHD inhibitor in H460 cells or in VHL-null RCC4 cells. In preclinical animal models, BAY 87-2243 dosed orally was well tolerated at therapeutic doses up to 15 mg/kg and showed moderate to high anti-tumor growth inhibitory activity as monotherapy in various subcutaneous and orthotopic xenograft models. Analysis of tumor samples demonstrated a decrease of nuclear HIF-1α protein level by immunohistochemistry as well as a specific suppression of HIF-1 target genes. These data indicate that specific inhibition of hypoxia-induced HIF-1 activation is achievable with small molecule inhibitors and is a novel approach to cancer therapy. Vaupel P, Mayer A, Hockel M (2004) Tumor hypoxia and malignant progression. Methods Enzymol 381:335-354 M. J. Calzada, L. del Peso, Hypoxia inducible factors and cancer. Clin. Transl. Oncol. 2007, 9(5), 278-289: Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4509. doi:10.1158/1538-7445.AM2011-4509
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2011
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    detail.hit.zdb_id: 410466-3
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  • 6
    Online Resource
    Online Resource
    Wiley ; 2004
    In:  Journal of Neurochemistry Vol. 90, No. 3 ( 2004-08), p. 659-665
    In: Journal of Neurochemistry, Wiley, Vol. 90, No. 3 ( 2004-08), p. 659-665
    Abstract: The insulin receptor substrate of 53 kDa (IRSp53) is a target of the small GTPase cdc42 which is strongly enriched in the postsynaptic density of excitatory synapses. IRSp53 interacts with the postsynaptic shank1 scaffolding molecule in a cdc42 regulated manner. The functional significance of the cdc42/IRSp53 pathway in postsynaptic sites is however, unclear. Here we identify PSD‐95 as a second synaptic interaction partner of IRSp53. Interaction is mediated by a C‐terminal PDZ binding motif in IRSp53 and the second PDZ domain of PSD‐95. In HEK cells, overexpressed IRSp53 induces filopodia and targets PSD‐95 into these processes. Immunoprecipitation and immunocytochemistry experiments demonstrate that the interaction occurs at postsynaptic sites in the brain. By virtue of its PDZ‐binding and SH3 domains, IRSp53 is capable of inducing the formation of a triple complex (shank1/IRSp53/PSD‐95).
    Type of Medium: Online Resource
    ISSN: 0022-3042 , 1471-4159
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2004
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  • 7
    In: Nature Cell Biology, Springer Science and Business Media LLC, Vol. 8, No. 12 ( 2006-12), p. 1337-1347
    Type of Medium: Online Resource
    ISSN: 1465-7392 , 1476-4679
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2006
    detail.hit.zdb_id: 1494945-3
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  • 8
    In: Journal of Biological Chemistry, Elsevier BV, Vol. 284, No. 14 ( 2009-04), p. 9225-9236
    Type of Medium: Online Resource
    ISSN: 0021-9258
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2009
    detail.hit.zdb_id: 2141744-1
    detail.hit.zdb_id: 1474604-9
    SSG: 12
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