title: The phenotypes of ATG9, ATG16 and ATG9/16 knock-out mutants imply autophagy-dependent and -independent functions.
abstract: Macroautophagy is a highly conserved intracellular bulk degradation system of all eukaryotic cells. It is governed by a large number of autophagy proteins (ATGs) and is crucial for many cellular processes. Here, we describe the phenotypes of Dictyostelium discoideum ATG16(-) and ATG9(-)/16(-) cells and compare them to the previously reported ATG9(-) mutant. ATG16 deficiency caused an increase in the expression of several core autophagy genes, among them atg9 and the two atg8 paralogues. The single and double ATG9 and ATG16 knock-out mutants had complex phenotypes and displayed severe and comparable defects in pinocytosis and phagocytosis. Uptake of Legionella pneumophila was reduced. In addition, ATG9(-) and ATG16(-) cells had dramatic defects in autophagy, development and proteasomal activity which were much more severe in the ATG9(-)/16(-) double mutant. Mutant cells showed an increase in poly-ubiquitinated proteins and contained large ubiquitin-positive protein aggregates which partially co-localized with ATG16-GFP in ATG9(-)/16(-) cells. The more severe autophagic, developmental and proteasomal phenotypes of ATG9(-)/16(-) cells imply that ATG9 and ATG16 probably function in parallel in autophagy and have in addition autophagy-independent functions in further cellular processes.
authors: Zentrum für Biochemie, Medizinische Fakultät, Universität zu Köln, Joseph-Stelzmann-Strasse 52, Köln 50931, Germany.
authors: Qiuhong
authors: Q
authors: Xiong
authors: Institut für Mikrobiologie, Technische Universität Braunschweig, Spielmannstrasse 7, Braunschweig 38106, Germany Fen Fakültesi, Türk-Alman-Üniversitesi, Istanbul 34820, Turkey.
authors: Can
authors: C
authors: Ünal
authors: Zentrum für Biochemie, Medizinische Fakultät, Universität zu Köln, Joseph-Stelzmann-Strasse 52, Köln 50931, Germany.
authors: Jan
authors: J
authors: Matthias
authors: Institut für Mikrobiologie, Technische Universität Braunschweig, Spielmannstrasse 7, Braunschweig 38106, Germany Helmholtz Centre for Infection Research, Braunschweig 38124, Germany.
authors: Michael
authors: M
authors: Steinert
authors: Zentrum für Biochemie, Medizinische Fakultät, Universität zu Köln, Joseph-Stelzmann-Strasse 52, Köln 50931, Germany ludwig.eichinger@uni-koeln.de.
authors: Ludwig
authors: L
authors: Eichinger
mesh_terms: D001343:Autophagy / Q000235:genetics*; D015153:Blotting, Western; D004023:Dictyostelium / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D055786:Gene Knockout Techniques; D016952:Legionella pneumophila / Q000502:physiology; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009154:Mutation; D010587:Phagocytosis / Q000235:genetics; D010588:Phagosomes / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D010873:Pinocytosis / Q000235:genetics; D025821:Polyubiquitin / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D057149:Ubiquitinated Proteins / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D008164:Luminescent Proteins; D015800:Protozoan Proteins; D057149:Ubiquitinated Proteins; D033921:Vesicular Transport Proteins; D025821:Polyubiquitin; D046988:Proteasome Endopeptidase Complex
keywords: Dictyostelium; autophagy; development; phagocytosis; proteasome; protein aggregate