Ccz1p/Aut11p/Cvt16p is essential for autophagy and the cvt pathway

Meiling-Wesse, Khuyen; Barth, Henning; Thumm, Michael

doi:10.1016/s0014-5793(02)03119-8

Cited by 62 publications

(42 citation statements)

References 26 publications

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“…Upon entry into the vacuole, we and others showed previously that GFP-ATG8a-PE is digested during autophagic body turnover to release free GFP in a soluble, relatively stable form (Meiling-Wesse et al, 2002;Chung et al, 2010). This free vacuolar GFP accumulates to high levels when autophagy is accelerated by nutrient starvation and thus represents a second reporter for ATG8-PE transport into vacuoles.…”

Section: Plants Missing Atg13 Senesce Early and Are Hypersensitive Tomentioning

confidence: 82%

The ATG1/ATG13 Protein Kinase Complex Is Both a Regulator and a Target of Autophagic Recycling in Arabidopsis

et al. 2011

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Autophagy is an intracellular recycling route in eukaryotes whereby organelles and cytoplasm are sequestered in vesicles, which are subsequently delivered to the vacuole for breakdown. The process is induced by various nutrient-responsive signaling cascades converging on the Autophagy-Related1 (ATG1)/ATG13 kinase complex. Here, we describe the ATG1/13 complex in Arabidopsis thaliana and show that it is both a regulator and a target of autophagy. Plants missing ATG13 are hypersensitive to nutrient limitations and senesce prematurely similar to mutants lacking other components of the ATG system. Synthesis of the ATG12-ATG5 and ATG8-phosphatidylethanolamine adducts, which are essential for autophagy, still occurs in ATG13-deficient plants, but the biogenesis of ATG8-decorated autophagic bodies does not, indicating that the complex regulates downstream events required for autophagosome enclosure and/or vacuolar delivery. Surprisingly, levels of the ATG1a and ATG13a phosphoproteins drop dramatically during nutrient starvation and rise again upon nutrient addition. This turnover is abrogated by inhibition of the ATG system, indicating that the ATG1/13 complex becomes a target of autophagy. Consistent with this mechanism, ATG1a is delivered to the vacuole with ATG8-decorated autophagic bodies. Given its responsiveness to nutrient demands, the turnover of the ATG1/13 kinase likely provides a dynamic mechanism to tightly connect autophagy to a plant's nutritional status.

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Section: Plants Missing Atg13 Senesce Early and Are Hypersensitive Tomentioning

confidence: 82%

The ATG1/ATG13 Protein Kinase Complex Is Both a Regulator and a Target of Autophagic Recycling in Arabidopsis

et al. 2011

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“…This fusion step involves components that are common to other transport processes that terminate at the vacuole. Thus, the Rab protein Ypt7, its GDP exchange factor complex Ccz1-Mon1, and SNARE proteins including Vam3, Vam7, Vti1, and Ykt6, along with the class C Vps/HOPS complex, are needed for tethering and fusion (Darsow et al 1997;Rieder and Emr 1997;Ishihara et al 2001;Meiling-Wesse et al 2002;Wang et al 2002;Nair et al 2011;Polupanov et al 2011). The fusion of the autophagosome outer membrane with the vacuole-limiting membrane releases the inner vesicle into the lumen (Figure 1).…”

Section: Macroautophagymentioning

confidence: 99%

Autophagic Processes in Yeast: Mechanism, Machinery and Regulation

2013

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Autophagy refers to a group of processes that involve degradation of cytoplasmic components including cytosol, macromolecular complexes, and organelles, within the vacuole or the lysosome of higher eukaryotes. The various types of autophagy have attracted increasing attention for at least two reasons. First, autophagy provides a compelling example of dynamic rearrangements of subcellular membranes involving issues of protein trafficking and organelle identity, and thus it is fascinating for researchers interested in questions pertinent to basic cell biology. Second, autophagy plays a central role in normal development and cell homeostasis, and, as a result, autophagic dysfunctions are associated with a range of illnesses including cancer, diabetes, myopathies, some types of neurodegeneration, and liver and heart diseases. That said, this review focuses on autophagy in yeast. Many aspects of autophagy are conserved from yeast to human; in particular, this applies to the gene products mediating these pathways as well as some of the signaling cascades regulating it, so that the information we relate is relevant to higher eukaryotes. Indeed, as with many cellular pathways, the initial molecular insights were made possible due to genetic studies in Saccharomyces cerevisiae and other fungi. TABLE OF CONTENTS Abstract 341Introduction 342

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“…27 The Ccz1-Mon1 protein complex acts together with Ypt7 in these fusion processes. [37][38][39] The Ypt7 homologue, Rab7, has been shown to be involved in autophagosome-lysosome fusion in mammalian cells, 31,40,41 Vam3, Vam7 and Vti1 are SNARE proteins involved in fusion in yeast. 42,43 The key question remaining to be answered is what is the SNARE molecule residing in autophagosomes (corresponding to v-SNARE) and how it is delivered.…”

Section: Transport and Fusionmentioning

confidence: 99%

The late stages of autophagy: how does the end begin?

2009

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Autophagy is a catabolic cellular process involving dynamic membrane rearrangement. Here, we review the understanding of autophagy, focusing on the late stages of the process, from the closing of the autophagosome to fusion with the lysosome. We propose the Reverse fusion model, for the closing autophagosome. In this model, autophagosome closure proceeds in a topologically similar but reverse order to membrane fusion during the escape of influenza virus from the endosome. This dynamic process is thought to be directly catalyzed by LC3, an ubiquitin-like molecule. Further, we discuss the dynamics of the Atg16L complex in relation to the LC3 localization in these processes. Finally, the molecular mechanisms involved in the delivery of autophagosomes to the lysosome and fusion are introduced. Several key events exist in each step and seem to be coordinated to faithfully conduct the autophagic process.

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Ccz1p/Aut11p/Cvt16p is essential for autophagy and the cvt pathway

Cited by 62 publications

References 26 publications

The ATG1/ATG13 Protein Kinase Complex Is Both a Regulator and a Target of Autophagic Recycling in Arabidopsis

The ATG1/ATG13 Protein Kinase Complex Is Both a Regulator and a Target of Autophagic Recycling in Arabidopsis

Autophagic Processes in Yeast: Mechanism, Machinery and Regulation

The late stages of autophagy: how does the end begin?

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