Die Bedeutung mitochondrialer Entkoppler-Proteine für die Regulation reaktiver Sauerstoffspezies
Zusammenfassung der Projektergebnisse
Mitochondria produce a substantial amount of reactive oxygen species (ROS) and their derivatives, reactive aldehydes, such as 4-hydroxy-2-nonenal (HNE). At high concentration HNE elicit deleterious effects primarily by oxidizing intracellular components, including lipids, DNA and proteins. At low concentrations it is thought to be a signaling molecule, regulating a range of physiological processes in organism. We investigated the involvement of 4-hydroxy-2-nonenal in the regulation of UCP-mediated mitochondrial uncoupling. One of the best known members of the UCP family is UCP1, which participates in non-shivering thermogenesis by dissipating the proton motive force to heat. We used two different strategies: (i) we directly measured proton currents through purified recombinant proteins reconstituted in planar bilayer membranes and (ii) we analyzed UCP’s content at the mRNA and protein levels in cells (neurons, lymphocytes, stem cells and cell lines (neuroblastoma, astrocyte)) and tissues under physiological and pathological (oxidative stress) conditions. For this, we first established validated antibodies as a correct tool for the UCPs detection in cells and tissues. We showed that no up-regulation of UCP2, UCP4 and UCP5 occurs under oxidative stress conditions in the models of cell differentiation in embryos and of hypoxia. The comparison of protein-free and protein-containing membranes demonstrated no direct activating effect of HNE on UCP1 or UCP2. Surprisingly, HNE potentiated the fatty acid-mediated increase of membrane conductance, Gm, in both UCP-containing and UCP-free membranes. The application of high potentials additionally stimulated the Gm increase. To explain the molecular mechanisms of HNE effects, we suggested that HNE simultaneously (1) alters the lipid membrane parameters (e.g. fluidity or dipole potential), which facilitates fatty acid transport and (2) induces a conformational change of UCP1 that opens a proton channel. Further investigations of UCP regulation at the molecular level may have important implications in the treatment of obesity (UCP1), neurodegenerative (UCP4), immunological (UCP2) diseases, and cancer (UCP2). Publications in PloS One led to a large number of press reports, for example: Der Spiegel vom 25.11.2013 S. 133: Fett weg im Schlaf
Projektbezogene Publikationen (Auswahl)
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(2009). Comparative analysis of uncoupling protein 4 distribution in various tissues under physiological conditions and during development. Biochim. Biophys. Acta 1788, 2309-2319
Smorodchenko, A., Rupprecht, A., Sarilova, I., Ninnemann, O., Brauer, A. U., Franke, K., Schumacher, S., Techritz, S., Nitsch, R., Schuelke, M., and Pohl, E.E.
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(2010). Role of the transmembrane potential in the membrane proton leak. Biophys. J. 98, 1503-1511
Rupprecht, A., Sokolenko, E. A., Beck, V., Ninnemann, O., Jaburek, M., Trimbuch, T., Klishin, S. S., Jezek, P., Skulachev, V. P., and Pohl, E.E.
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(2010): Involving of 4-hydroxy-2-nonenal in the activation of UCP1. BBA-Bioenergetics (1797) 90-90
Sokolenko, EA; Rupprecht, A; Pohl, EE
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(2010): Mitochondrial uncoupling protein 4 (UCP4) expression in rat inner ear during development and after oxidative stress induction. BBA-Bioenergetics (1797) 90-90
Smorodchenko, A; Rupprecht, A; Fuchs, J; Gross, J; Pohl, EE
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(2010): UCP2 expression pattern in mouse tissue. BBA-Bioenergetics (1797) 89-89
Rupprecht, A; Sittner, D; Goyn, J; Smorodchenko, A; Brauer, AU; Seiler, A; Pohl, EE
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(2011). Linking of sensor molecules with amino groups to amino-functionalized AFM tips. Bioconjugate Chem. 22, 1239–1248
Wildling, L., Unterauer, B., Zhu, R., Rupprecht, A., Haselgruebler, T., Rankl, C., Ebner, A., Vater, D., Pollheimer, P., Pohl, E.E., Hinterdorfer, P., Gruber, H. J.
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(2011). Role of mitochondrial uncoupling protein 4 in rat inner ear. Mol. Cell. Neurosci. 47(4), 244-53
Smorodchenko, A., Rupprecht, A., Fuchs, J., Gross, J., Pohl, E.E.
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(2012) Quantification of Uncoupling protein 2 reveals its main expression in immune cells and selective up-regulation during T-cell proliferation. PLoS ONE 7(8): e41406
Rupprecht, A., Bräuer, A.U., Smorodchenko, A., Goyn, J., Hilse K.E., Shabalina I.G., Infante-Duarte, C., Pohl, E.E.
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(2012): UCP2 is associated with a high cell proliferative potential and therefore not present in neurons. BBA-Bioenergetics (1817) S44-S44
Rupprecht, A; Brauer, AU; Smorodchenko, A; Hilse, KE; Infante-Duarte, C; Pohl, EE
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(2013) Fatty acids are key in 4-hydroxy-2-nonenal-mediated activation of uncoupling proteins 1 and 2. PLoS ONE 8(10): e77786
Malingriaux, E.A., Rupprecht, A., Gille, L., Jovanovic, O., Jezek P., Jaburek, M., Pohl, E.E.
