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International Journal of Cell Biology
Volume 2012, Article ID 179207, 13 pages
http://dx.doi.org/10.1155/2012/179207
Research Article

WIPI-1 Positive Autophagosome-Like Vesicles Entrap Pathogenic Staphylococcus aureus for Lysosomal Degradation

1Autophagy Laboratory, Interfaculty Institute for Cell Biology, Eberhard Karls University Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
2Microbial Genetics, Interfaculty Institute for Microbiology and Infectious Medicine, University of Tübingen, 72076 Tübingen, Germany
3Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, 50935 Cologne, Germany
4Leibniz Institute for Arteriosclerosis Research, University of Münster, 48149 Münster, Germany

Received 14 November 2011; Revised 31 January 2012; Accepted 6 February 2012

Academic Editor: Anne Simonsen

Copyright © 2014 Cinzia Fabrizi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Invading pathogens provoke the autophagic machinery and, in a process termed xenophagy, the host cell survives because autophagy is employed as a safeguard for pathogens that escaped phagosomes. However, some pathogens can manipulate the autophagic pathway and replicate within the niche of generated autophagosome-like vesicles. By automated fluorescence-based high content analyses, we demonstrate that Staphylococcus aureus strains (USA300, HG001, SA113) stimulate autophagy and become entrapped in intracellular PtdIns(3)P-enriched vesicles that are decorated with human WIPI-1, an essential PtdIns(3)P effector of canonical autophagy and membrane protein of both phagophores and autophagosomes. Further, agr-positive S. aureus (USA300, HG001) strains were more efficiently entrapped in WIPI-1 positive autophagosome-like vesicles when compared to agr-negative cells (SA113). By confocal and electron microscopy we provide evidence that single- and multiple-Staphylococci entrapped undergo cell division. Moreover, the number of WIPI-1 positive autophagosome-like vesicles entrapping Staphylococci significantly increased upon (i) lysosomal inhibition by bafilomycin A1 and (ii) blocking PIKfyve-mediated PtdIns(3,5)P2 generation by YM201636. In summary, our results provide evidence that the PtdIns(3)P effector function of WIPI-1 is utilized during xenophagy of Staphylococcus aureus. We suggest that invading S. aureus cells become entrapped in autophagosome-like WIPI-1 positive vesicles targeted for lysosomal degradation in nonprofessional host cells.