Franziska Panther

University of Wuerzburg, Würzburg, Bavaria, Germany

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Publications (4)22.82 Total impact

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    ABSTRACT: Inhibition of calcineurin (CnA) activity by cyclosporine A (CsA) is the mainstay in immunosuppressive therapy. CsA inhibits the phosphatase activity of the cytosolic phosphatase CnA and, therefore, prevents the dephosphorylation and subsequently nuclear translocation of the transcription factor nuclear factor of activated T cells (NFAT). However, CsA has multiple other targets within the cell and is, therefore, not specific. We developed a new approach to inhibit CnA/NFAT signaling. This synthetic peptide prevented CnA nuclear translocation in vitro. The purpose of this study was to demonstrate that this novel approach could potentially inhibit T-cell function in vitro and in vivo. T-cell activation (Jurkat T cells, naïve rat T cells, and peripheral human T cells) was assessed by protein synthesis, interleukin (IL)-2 promoter activity, and IL-2 levels after T-cell activation. Immunohistological stainings for CnA were performed to investigate nuclear localization of CnA. The immunosuppressive effects in vivo of the synthetic peptide were investigated in rats with heterotopic transplanted hearts. The nuclear localization signal peptide significantly decreased alloantigen-specific T-lymphocyte proliferation, IL-2 promoter activity, and IL-2 production (338% ± 27% vs. 149% ± 11%, n=8, P<0.05) in cultured T cells by inhibition of CnA nuclear translocation. The synthetic peptide also significantly decreased the number of graft infiltrating CD8 T lymphocytes. Moreover, treatment with the synthetic inhibitory inhibited acute graft rejection (5 ± 0.6 days vs. 12 ± 2 days, n=10, P<0.05). Inhibition of nuclear translocation of CnA is a novel approach to inhibit the activation of the CnA/NFAT signaling cascade. Further studies have to demonstrate the long-term use of this principle in vivo.
    No preview · Article · Mar 2011 · Transplantation
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    ABSTRACT: We previously demonstrated that conditional overexpression of neuronal nitric oxide synthase (nNOS) inhibited L-type Ca2+ channels and decreased myocardial contractility. However, nNOS has multiple targets within the cardiac myocyte. We now hypothesize that nNOS overexpression is cardioprotective after ischemia/reperfusion because of inhibition of mitochondrial function and a reduction in reactive oxygen species generation. Ischemia/reperfusion injury in wild-type mice resulted in nNOS accumulation in the mitochondria. Similarly, transgenic nNOS overexpression caused nNOS abundance in mitochondria. nNOS translocation into the mitochondria was dependent on heat shock protein 90. Ischemia/reperfusion experiments in isolated hearts showed a cardioprotective effect of nNOS overexpression. Infarct size in vivo was also significantly reduced. nNOS overexpression also caused a significant increase in mitochondrial nitrite levels accompanied by a decrease of cytochrome c oxidase activity. Accordingly, O(2) consumption in isolated heart muscle strips was decreased in nNOS-overexpressing nNOS(+)/αMHC-tTA(+) mice already under resting conditions. Additionally, we found that the reactive oxygen species concentration was significantly decreased in hearts of nNOS-overexpressing nNOS(+)/αMHC-tTA(+) mice compared with noninduced nNOS(+)/αMHC-tTA(+) animals. We demonstrated that conditional transgenic overexpression of nNOS resulted in myocardial protection after ischemia/reperfusion injury. Besides a reduction in reactive oxygen species generation, this might be caused by nitrite-mediated inhibition of mitochondrial function, which reduced myocardial oxygen consumption already under baseline conditions.
    Full-text · Article · Oct 2010 · Circulation
  • Franziska Panther · Tatjana Williams · Oliver Ritter
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    ABSTRACT: Calcineurin (Cn), a serine/threonine phosphatase, plays a crucial role in the development of myocardial hypertrophy. Cn is a cytosolic phosphatase which dephosphorylates various target molecules, e.g. the transcriptional factor nuclear factor of activated T cells (NFAT), thereby enabling its nuclear translocation. Recently, it was demonstrated that not only NFAT, but also Cn is translocated into the nucleus. The nuclear coexistence of Cn and NFAT is important for the full transcriptional activity of the Cn-NFAT signalling cascade. Once Cn and NFAT have entered the nucleus of cardiomyocytes, the transcription of genes characteristic for myocardial hypertrophy (e.g. BNP, ANP) is initiated. The nuclear localization sequence (NLS), a region spanning amino acids 172-183 of calcineurin Abeta (CnAbeta) is essential for recognition and shuttling of Cn into the nucleus by importinbeta (1). A synthetic import blocking peptide (IBP) that mimics the NLS of Cn was tested recently. The NLS analogon IBP saturates the Cn binding site of importinbeta(1) thereby preventing binding of Cn and importin. This inhibits the translocation of Cn into the nucleus. Inhibiting the Cn/importin interaction with competing synthetic peptides is one of several new approaches to prevent the development of myocardial hypertrophy. Several patents have also been filed on molecules related to inhibition of Cn-NFAT signalling.
    No preview · Article · Nov 2009
  • C Schimmer · F Panther · R Leyh · W Voelker · Oliver Ritter

    No preview · Article · Sep 2009 · Clinical Research in Cardiology