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Klein W, Rutz C, Eckhard J, Provinciael B, Specker E, Neuenschwander M, Kleinau G, Scheerer P, von Kries JP, Nazaré M, Vermeire K, Schülein R. Use of a sequential high throughput screening assay to identify novel inhibitors of the eukaryotic SRP-Sec61 targeting/translocation pathway. PLoS One 2018; 13:e0208641. [PMID: 30543669 PMCID: PMC6292634 DOI: 10.1371/journal.pone.0208641] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 11/20/2018] [Indexed: 11/22/2022] Open
Abstract
The SRP-Sec61 targeting/translocation pathway of eukaryotic cells targets nascent protein chains to the membrane of the endoplasmic reticulum. Using this machinery, secretory proteins are translocated across this membrane whereas membrane proteins are integrated into the lipid bilayer. One of the key players of the pathway is the protein-conducting Sec61 (translocon) complex of the endoplasmic reticulum. The Sec61 complex has no enzymatic activity, is expressed only intracellularly and is difficult to purify and to reconstitute. Screening for small molecule inhibitors impairing its functions is thus notoriously difficult. Such inhibitors may not only be valuable tools for cell biology, they may also represent novel anti-tumor drugs. Here we have developed a two-step, sequential screening assay for inhibitors of the whole SRP-Sec61 targeting/translocation pathway which might include molecules affecting Sec61 complex functions. The resulting hit compounds were analyzed using a whole cell biosynthesis assay and a cell free transcription/translation/translocation assay. Using this methodology, we identified novel compounds inhibiting this pathway. Following structure-based back screening, one of these substances was analyzed in more detail and we could show that it indeed impairs translocation at the level of the Sec61 complex. A slightly modified methodology may be used in the future to screen for substances affecting SecYEG, the bacterial ortholog of the Sec61 complex in order to derive novel antibiotic drugs.
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Affiliation(s)
- Wolfgang Klein
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Claudia Rutz
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Jamina Eckhard
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Becky Provinciael
- KU Leuven, Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Edgar Specker
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | | | - Gunnar Kleinau
- Charité—Universitätsmedizin Berlin, Campus Charité Mitte, Charité Centrum Grundlagenmedizin CC2, Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography & Signal Transduction, Berlin, Germany
| | - Patrick Scheerer
- Charité—Universitätsmedizin Berlin, Campus Charité Mitte, Charité Centrum Grundlagenmedizin CC2, Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography & Signal Transduction, Berlin, Germany
| | | | - Marc Nazaré
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Kurt Vermeire
- KU Leuven, Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Ralf Schülein
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
- * E-mail:
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Liss M, Radke MH, Eckhard J, Neuenschwander M, Dauksaite V, von Kries JP, Gotthardt M. Drug discovery with an RBM20 dependent titin splice reporter identifies cardenolides as lead structures to improve cardiac filling. PLoS One 2018; 13:e0198492. [PMID: 29889873 PMCID: PMC5995442 DOI: 10.1371/journal.pone.0198492] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 05/20/2018] [Indexed: 02/07/2023] Open
Abstract
Diastolic dysfunction is increasingly prevalent in our ageing society and an important contributor to heart failure. The giant protein titin could serve as a therapeutic target, as its elastic properties are a main determinant of cardiac filling in diastole. This study aimed to develop a high throughput pharmacological screen to identify small molecules that affect titin isoform expression through differential inclusion of exons encoding the elastic PEVK domains. We used a dual luciferase splice reporter assay that builds on the titin splice factor RBM20 to screen ~34,000 small molecules and identified several compounds that inhibit the exclusion of PEVK exons. These compounds belong to the class of cardenolides and affect RBM20 dependent titin exon exclusion but did not affect RBFOX1 mediated splicing of FMNL3. We provide evidence that cardenolides do not bind to the RNA interacting domain of RBM20, but reduce RBM20 protein levels and alter transcription of select splicing factors that interact with RBM20. Cardenolides affect titin isoform expression. Understanding their mode of action and harnessing the splice effects through chemical modifications that suppress the effects on ion homeostasis and more selectively affect cardiac splicing has the potential to improve cardiac filling and thus help patients with diastolic heart failure, for which currently no targeted therapy exists.
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Affiliation(s)
- Martin Liss
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Michael H. Radke
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Berlin, Germany
| | - Jamina Eckhard
- Screening Unit, Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
| | | | - Vita Dauksaite
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | | | - Michael Gotthardt
- Neuromuscular and Cardiovascular Cell Biology, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Berlin, Germany
- * E-mail:
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Günther C, Lee-Kirsch MA, Eckhard J, Matanovic A, Kerscher T, Rüschendorf F, Klein B, Berndt N, Zimmermann N, Flachmeier C, Thuß T, Lucas N, Marenholz I, Esparza-Gordillo J, Hübner N, Traupe H, Delaporte E, Lee YA. SMARCAD1 Haploinsufficiency Underlies Huriez Syndrome and Associated Skin Cancer Susceptibility. J Invest Dermatol 2018; 138:1428-1431. [DOI: 10.1016/j.jid.2018.01.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 12/17/2017] [Accepted: 01/06/2018] [Indexed: 11/26/2022]
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Günther C, Lee-Kirsch M, Eckhard J, Matanovic A, Rüschendorf F, Klein B, Esparza-Gordillo J, Traupe H, Delaporte E, Lee Y. 781 SMARCAD1 haploinsufficiency underlies Huriez Syndrome and associated skin cancer susceptibility. J Invest Dermatol 2018. [DOI: 10.1016/j.jid.2018.03.791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Dickhaut K, Hoepner S, Eckhard J, Wiesmueller KH, Schindler L, Jung G, Falk K, Roetzschke O. Enhancement of tumour-specific immune responses in vivo by 'MHC loading-enhancer' (MLE). PLoS One 2009; 4:e6811. [PMID: 19738910 PMCID: PMC2735034 DOI: 10.1371/journal.pone.0006811] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Accepted: 08/03/2009] [Indexed: 12/05/2022] Open
Abstract
Background Class II MHC molecules (MHC II) are cell surface receptors displaying short protein fragments for the surveillance by CD4+ T cells. Antigens therefore have to be loaded onto this receptor in order to induce productive immune responses. On the cell surface, most MHC II molecules are either occupied by ligands or their binding cleft has been blocked by the acquisition of a non-receptive state. Direct loading with antigens, as required during peptide vaccinations, is therefore hindered. Principal Findings Here we show, that the in vivo response of CD4+ T cells can be improved, when the antigens are administered together with ‘MHC-loading enhancer’ (MLE). MLE are small catalytic compounds able to open up the MHC binding site by triggering ligand-release and stabilizing the receptive state. Their enhancing effect on the immune response was demonstrated here with an antigen from the influenza virus and tumour associated antigens (TAA) derived from the NY-ESO-1 protein. The application of these antigens in combination with adamantane ethanol (AdEtOH), an MLE compound active on human HLA-DR molecules, significantly increased the frequency of antigen-specific CD4+ T cells in mice transgenic for the human MHC II molecule. Notably, the effect was evident only with the MLE-susceptible HLA-DR molecule and not with murine MHC II molecules non-susceptible for the catalytic effect of the MLE. Conclusion MLE can specifically increase the potency of a vaccine by facilitating the efficient transfer of the antigen onto the MHC molecule. They may therefore open a new way to improve vaccination efficacy and tumour-immunotherapy.
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Affiliation(s)
- Katharina Dickhaut
- Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany
- Charité, Berlin, Germany
| | - Sabine Hoepner
- Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany
| | - Jamina Eckhard
- Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany
| | | | | | | | - Kirsten Falk
- Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany
- * E-mail:
| | - Olaf Roetzschke
- Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore
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Opitz B, Rejaibi A, Dauber B, Eckhard J, Vinzing M, Schmeck B, Hippenstiel S, Suttorp N, Wolff T. IFNbeta induction by influenza A virus is mediated by RIG-I which is regulated by the viral NS1 protein. Cell Microbiol 2007; 9:930-8. [PMID: 17140406 DOI: 10.1111/j.1462-5822.2006.00841.x] [Citation(s) in RCA: 225] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Influenza A virus causes epidemics of respiratory diseases in humans leading to thousands of death annually. One of its major virulence factors, the non-structural protein 1 (NS1), exhibits interferon-antagonistic properties. While epithelial cells of the respiratory tract are the primary targets of influenza virus, the virus-sensing mechanisms in these cells eventually leading to IFNbeta production are incompletely understood. Here we show that infection of epithelial cells with NS1-deficient influenza A virus upregulated expression of two molecules that have been previously implicated in sensing of RNA viruses, the retinoic acid-inducible gene I (RIG-I) and the melanoma differentiation-associated gene 5 (MDA5). Gene silencing and overexpression experiments demonstrated that RIG-I, its adapter interferon-beta promoter stimulator 1 (IPS-1) and interferon-regulated factor 3 (IRF3) were involved in influenza A virus-mediated production of the antiviral IFNbeta. In addition, we showed that the NS1 protein is capable to inhibit the RIG-I-induced signalling, a mechanism which corresponded to the observation that only NS1-deficient but not the wild-type virus induced high-level production of IFNbeta. In conclusion, we demonstrated a critical involvement of RIG-I, IPS-1 and IRF3 in influenza A virus infection of epithelial cells.
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Affiliation(s)
- Bastian Opitz
- Department of Internal Medicine/Infectious Diseases and Pulmonary Medicine, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
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Abstract
A rapid and precise method is described for the determination of total free fatty acids (FFA) in the serum followed by the separation of individual FFA by gas-liquid chromatography (GLC). After the extraction the FFA are directly injected into the gas-liquid chromatograph without esterification. DEGS-PS serves as stationary phase. The esterified fatty acids such as cholesterol esters, phospholipids or triglycerides do not interfere with the FFA determined by the GLC method. This method is compared to other commonly used titrimetric and gas-chromatographic procedures. The changes of the composition of individual FFA during and after ergometer work is reported.
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