The Atg1-Atg13 Complex Regulates Atg9 and Atg23 Retrieval Transport from the Pre-Autophagosomal Structure

Reggiori, Fulvio; Tucker, Katherine A; Strømhaug, Per E.; Klionsky, Daniel J.

doi:10.1016/s1534-5807(03)00402-7

Cited by 439 publications

(638 citation statements)

References 37 publications

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“…The PI3P-binding protein Atg18/WIPI and its binding partner Atg2 are recruited to such a platform. Although the exact function of Atg2-Atg18/WIPI in autophagosome biogenesis is not clear, it has been shown that the Atg2-Atg18 complex is required for normal distribution of Atg9 vesicles [38][39][40].…”

Section: The Atg1/ulk Complexmentioning

confidence: 99%

A current perspective of autophagosome biogenesis

2013

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Autophagy is a bulk degradation system induced by cellular stresses such as nutrient starvation. Its function relies on the formation of double-membrane vesicles called autophagosomes. Unlike other organelles that appear to stably exist in the cell, autophagosomes are formed on demand, and once their formation is initiated, it proceeds surprisingly rapidly. How and where this dynamic autophagosome formation takes place has been a long-standing question, but the discovery of Atg proteins in the 1990's significantly accelerated our understanding of autophagosome biogenesis. In this review, we will briefly introduce each Atg functional unit in relation to autophagosome biogenesis, and then discuss the origin of the autophagosomal membrane with an introduction to selected recent studies addressing this problem.

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Section: The Atg1/ulk Complexmentioning

confidence: 99%

A current perspective of autophagosome biogenesis

2013

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“…18,19 Atg9 is the only currently characterized transmembrane protein involved in the formation of double-membrane vesicles, and is thought to mark membranes to be donated to the PAS. 20 Atg1 regulates the shuttling of Atg9 between the PAS and a peripheral pool and in this way is thought to control retrieval of Atg9 and the associated membrane 20 (Figure 2). …”

Section: Macroautophagy In Yeast Is a Multistep Process That Is Regulmentioning

confidence: 99%

“…Atg13 and Atg1 also form a complex with Atg17, which is involved in regulating the size of the vesicles during autophagy. 27,28 Another way that Atg1p differentially regulates the cvt and autophagy pathways is through the recycling of Atg9p and/or Atg23p (a peripheral membrane protein) depending on the kinase activity of Atg1p 20 . Similar to Atg11, Atg23 is essential for cvt.…”

Section: Macroautophagy In Yeast Is a Multistep Process That Is Regulmentioning

confidence: 99%

Macroautophagy versus mitochondrial autophagy: a question of fate?

Kundu

Thompson²

2005

Cell Death Differ

106

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Autophagy is a catabolic process that allows recycling of cytoplasmic components (including organelles) into basic components, offering a bioenergetically efficient alternative to de novo synthesis. In yeast, autophagy functions primarily as an adaptive mechanism allowing survival in the response to changes in the availability of nutrients in the environment. Over the past decade, genetic screens performed in yeast have elucidated many of the molecular components involved in this adaptive response. [1][2][3] More recently, the roles of homologous genes are being explored in multicellular organisms and in cells derived from these organisms. 4 These studies have demonstrated that while autophagy is often induced as part of an adaptive response, induction of autophagy may also lead to cell death. During Drosophila larval development, for example, starvation-induced autophagy occurs in the larval fat body and is required for maintaining circulating nutrient levels and survival of the larvae under unfavorable nutritional conditions; 5 by contrast, programmed autophagy results in cell death and is the primary means of removing certain larval organs during metamorphosis. 6 On a cellular level, autophagy is observed prior to apoptosis in growth factor-deprived neuronal cultures. 7,8 In cells lacking critical proapoptotic proteins, the adaptive process of autophagy aimed at maintaining bioenergetic homeostasis can be unmasked in response to growthfactor withdrawal. 9 In contrast, cell death in response to a variety of chemicals has been suggested to result from autophagic destruction of the cell and to be suppressed by inhibition of autophagy. 10 The factors that determine whether induction of autophagy contributes to cell survival or cell death are not well-elucidated; however, two key issues may be the rate of autophagic degradation and the specificity of the engulfed components. Although autophagy is generally considered a nonspecific process, there are instances where the mitochondria (and other organelles) appear to be specifically targeted. Here, we focus on the signals and pathways involved in regulating the induction of autophagy and mitochondrial autophagy in yeast and how these processes are relevant to survival and death of mammalian cells.In general terms, 'autophagy' refers to any intracellular process that involves the degradation of cytosolic components by the lysosome. There are at least three distinct autophagic pathways: macroautophagy, microautophagy and chaperone-mediated autophagy. Macroautophagy is a multistep process by which portions of cytoplasm and/or organelles are sequestered in a double or multimembrane structure ('autophagosome') and delivered to the lysosome for degradation (Figure 1). Upon fusion of the autophagosome with the lysosome, it becomes an autophagolysosome or autophagic vacuole. Although macroautophagy is generally considered a nonspecific process there are instances in which organelles, such as mitochondria and peroxisomes, appear to be preferentially sequestered. These process...

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“…One of the most intriguing questions is the origin of the membrane for the double-membrane Cvt vesicles or autophagosomes. Recent data suggest that Atg9 may mark the membrane that is donated to the forming sequestering vesicles (Noda et al, 2000;Reggiori et al, 2004a). Atg9 localizes to mitochondria and cycles between this compartment and the pre-autophagosomal structure (PAS), the site of organization for Cvt vesicle and autophagosome formation (Tucker et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Atg27 Is Required for Autophagy-dependent Cycling of Atg9

Yen

Legakis

Nair

et al. 2007

MBoC

Self Cite

162

142

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Autophagy is a catabolic pathway for the degradation of cytosolic proteins or organelles and is conserved among all eukaryotic cells. The hallmark of autophagy is the formation of double-membrane cytosolic vesicles, termed autophagosomes, which sequester cytoplasm; however, the mechanism of vesicle formation and the membrane source remain unclear. In the yeast Saccharomyces cerevisiae, selective autophagy mediates the delivery of specific cargos to the vacuole, the analog of the mammalian lysosome. The transmembrane protein Atg9 cycles between the mitochondria and the pre-autophagosomal structure, which is the site of autophagosome biogenesis. Atg9 is thought to mediate the delivery of membrane to the forming autophagosome. Here, we characterize a second transmembrane protein Atg27 that is required for specific autophagy in yeast. Atg27 is required for Atg9 cycling and shuttles between the pre-autophagosomal structure, mitochondria, and the Golgi complex. These data support a hypothesis that multiple membrane sources supply the lipids needed for autophagosome formation.

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The Atg1-Atg13 Complex Regulates Atg9 and Atg23 Retrieval Transport from the Pre-Autophagosomal Structure

Cited by 439 publications

References 37 publications

A current perspective of autophagosome biogenesis

A current perspective of autophagosome biogenesis

Macroautophagy versus mitochondrial autophagy: a question of fate?

Atg27 Is Required for Autophagy-dependent Cycling of Atg9

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