Project 1
Ludwig Eichinger, Angelika Anna Noegel
The professional phagocyte Dictyostelium as a host model for pathogens
Institute for Biochemistry, University of Cologne
Brief description in German:
Organismen verfügen über viele Mechanismen, um Pathogene abzuwehren und zu bekämpfen, dazu gehört die Aufnahme in Fresszellen durch Phagozytose und der folgende Erregerabbau. Wir untersuchen Phagozytose und Infektion in Dictyostelium discoideum, einem professionellen Phagozyten, der sich in den letzten Jahren auch als geeigneter Wirt für eine Reihe pathogener Mikroorganismen erwiesen hat. Wir werden in diesem Projekt sowohl die Rolle des Aktinzytoskeletts in der Phagozytose von Partikeln als auch von Makroautophagie in der Etablierung und Eliminierung von Pathogenen untersuchen.
To be able to cope with potential pathogens most organisms harbour specialized cells that have the ability to rapidly and efficiently internalize a variety of organisms and particles and degrade them. To analyse this process we use Dictyostelium discoideum, a professional phagocyte that has also been shown to be a suitable host for a number of pathogens.
We focus in this project on the roles of the actin cytoskeleton in the phagocytosis of particles and of the macroautophagic machinery in the intracellular establishment and elimination of pathogens.
The professional phagocyte Dictyostelium discoideum is a useful model for the study of complex biological processes like signal transduction, chemotaxis, cytokinesis, phagocytosis and the medically relevant infection by bacterial pathogens. We study the latter two processes focussing on actin-binding proteins and macroautophagy (hereafter autophagy). The involvement of actin and actin-binding proteins in the phagocytic process is well documented, however, the composition of the molecular machinery as well as the role of the different components is still poorly understood. The decision to study autophagy with respect to the infection process was based on a "top-down" approach using data from previous DNA microarray analyses.
In this approach we identified 240 genes specific for the cellular response to infection with Legionella pneumophila. Of these more than 50 genes have clear orthologues in man and three encode components of the autophagic machinery. Autophagy contributes to many physiological and pathological processes, including starvation, cell differentiation, development, innate immunity, programmed cell death, cancer and neurodegenerative disorders. However, its possible involvement in the host response to pathogens is still a matter of debate. Therefore, we selected the up-regulated atg9 gene for further studies.
The ATG9 protein is highly conserved from yeast to man and yeast ATG9 is important in the formation of the pre-autophagosome structure (PAS), the site of autophagosome assembly. Dictyostelium Atg9 knock-out cells displayed pleiotropic defects. They had growth defects in medium as well as on bacterial lawns indicative of defects in macropinocytosis and phagocytosis and also displayed severe developmental defects.
Remarkably, the phagocytosis defect of the Atg9- mutant was particularly apparent when infecting the cells with L. pneumophila. However, those Legionellae that entered the host were in the Atg9- cells in comparison to AX2 wild-type less efficiently cleared in the early phase and replicated faster in the late phase of infection. These results support a protective role of ATG9 and hence autophagy during pathogen infection.
In addition, we have expanded our microarray analysis of the infection process to two more pathogens, Mycobacterium marinum and Salmonella typhimurium. With this approach we will identify general and pathogen-specific host genes in response to infection with different pathogens. Interestingly, first results show differential regulation of autophagy genes for each of these pathogens emphasizing the importance of autophagy in the infection process.
List of publications resulting from the project
Peer-reviewed publications:
Shina, M.C., A. Müller-Taubenberger, C. Ünal, M. Schleicher, M. Steinert, L. Eichinger, R Müller, G. Glöckner, and A.A. Noegel. 2011. Redundant and unique roles of coronin proteins in Dictyostelium. Cell. Mol. Life Sci., 68, 303–313.
Shina, M.C., R. Müller, R. Blau-Wasser, G. Glöckner, M. Schleicher, L. Eichinger, A.A. Noegel, and W. Kolanus. 2010. A cytohesin homolog in Dictyostelium amoebae. PLoS ONE, 2, e9378.
Shina, M.C., C. Ünal, L. Eichinger, A. Müller-Taubenberger, M. Schleicher, M. Steinert, and A.A. Noegel. 2010. A Coronin7 homolog with functions in actin-driven processes. J. Biol. Chem., 285, 9249–9261.
Tung S.M., C. Ünal, A. Ley, C. Peña, B. Tunggal, A.A. Noegel, O. Krut, M. Steinert and L. Eichinger. 2010. Loss of Dictyostelium ATG9 results in a pleitropic phenotype affecting growth, development, phagocytosis and clearance and replication of Legionella pneumophila. Cell. Microbiol., 12, 765-780.
Lang, P.A., R.S. Kasinathan, V.B. Brand, C. Duranton, C. Lang, S. Koka, E. Shumilina, D.S. Kempe, V. Tanneur, A. Akel, K.S. Lang, M. Föller, J.F.J. Kun, P.G. Kremsner, S. Wesselborg, S. Laufer, C.S. Clemen, C. Herr, A.A. Noegel, T. Wieder, E. Gulbins, F. Lang, and S.M. Huber. 2009. Accelerated clearance of Plasmodium-infected erythrocytes in sickle cell trait and annexin-A7 deficiency. Cell Physiol. Biochem. 24, 415-428.
Sultana, H., G. Neelakanta, L. Eichinger, F. Rivero and A.A. Noegel. 2009. Microarray phenotyping places cyclase associated protein CAP at the crossroad of signaling pathways reorganizing the actin cytoskeleton in Dictyostelium. Exp. Cell Res., 315, 127-140.
Rybakin, V., R.H. Rastetter, M. Stumpf, A.C. Uetrecht, J.E. Bear, A.A. Noegel, and C.S. Clemen. 2008. Molecular mechanism underlying the association of Coronin-7 with Golgi membranes. Cell. Mol. Life Sci. 65, 2419-2430.
Farbrother, P., C. Wagner, J. Na, B. Tunggal, T. Morio, H. Urushihara, Y. Tanaka, M. Schleicher, M. Steinert, and L. Eichinger. 2006. Dictyostelium transcriptional host cell response upon infection with Legionella. Cell. Microbiol. 3, 438-456.
Marko, M., Y. Prabhu, R. Müller, R. Blau-Wasser, M. Schleicher, and A.A. Noegel. 2006. The annexins of Dictyostelium. Eur. J. Cell Biol. 85, 1011-1022.
Rybakin, V., N.V. Gounko, K. Späte, S. Höning, I.V. Majoul, R. Duden, and A A. Noegel. 2006. Crn7 interacts with AP-1 and is required for the maintenance of Golgi morphology and protein export from the Golgi. J. Biol. Chem. 281, 31070-31078.
Non peer-reviewed publications:
Xavier, C-P., L. Eichinger, M.P. Fernandez, R.O. Morgan and C.S. Clemen. 2008. Evolutionary and functional diversity of coronin proteins. In: The Coronin Protein Family. Eds: C.C. Clemen, L. Eichinger and V. Rybakin, Landes Bioscience, Austin, Texas and Springer Science+Business Media, New York, USA, 98-109.
Steinert, M., C. Wagner, M. Fajardo, O. Shevchuk, C. Ünal, F. Galka, K. Heuner, L. Eichinger and S. Bozzaro. 2007. The Amoeba Dictyostelium discoideum Contributes to Legionella Infection. In Legionella: State of the art 30 years after its recognition. Eds.: N.P. Cianciotto, Y. Abu Kwaik, P.H. Edelstein, B.S. Fields, D.F. Geary, T.G. Harrison, C. Joseph, R.M. Ratcliff, J.E. Stout and M.S. Swanson. ASM Press, Herndon, USA, 390-394.
