PI4P-signaling pathway for the synthesis of a nascent membrane structure in selective autophagy

Yamashita, Shunichi; Oku, Masahide; Wasada, Yuko; Ano, Yoshitaka; Sakai, Yasuyoshi

doi:10.1083/jcb.200512142

Cited by 78 publications

(77 citation statements)

References 31 publications

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“…It could be that the amount of sterol glucoside (SG) in S. cerevisiae 13 is too low to have any effect on these autophagy-related pathways. SG synthesis is higher in P. pastoris, and the SG content might influence MIPA formation and other membrane events in P. pastoris, which contributes to the involvement of PpAtg26 in pexophagy; 5 however, the role of the S. cerevisiae Atg26 protein, remains to be elucidated.…”

Section: Resultsmentioning

confidence: 99%

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Atg26 is Not Involved in Autophagy-Related Pathways inSaccharomyces cerevisiae

Cao¹,

Klionsky²

2007

Autophagy

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Previously published online a an Autophagy E-publication: http://www.landesbioscience.com/journals/autophagy/abstract.php?id=3371 KEY WORDScytoplasm to vacuole targeting, lysosome, pexophagy, protein transport, vacuole, yeast Atg26 is Not Involved in Autophagy-Related Pathways in Saccharomyces cerevisiae ABSTRACTAutophagy is a degradative pathway conserved among eukaryotes. It is a major route for degradation of long-lived proteins and entire organelles, such as peroxisomes. Atg26, a sterol glucosyltransferase, is specifically required for micro-and macropexophagy, but not for starvation-induced bulk autophagy in Pichia pastoris. Here we study the requirement of Saccharomyces cerevisiae Atg26 in the Cvt pathway, nonspecific autophagy and pexophagy. Our results show that the S. cerevisiae atg26∆ strain is not defective in prApe1 maturation, macroautophagy or peroxisome degradation, in contrast to the situation seen in Pichia pastoris. These studies highlight the importance of examining mutants in multiple organisms.

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Section: Resultsmentioning

confidence: 99%

“…4 PpAtg26 is also required for the formation of the MIPA structure. 5 The three domains of PpAtg26, pleckstrin homology (PH), GRAM and catalytic UDP-glucosyl transferase (UDPGT) domains, are all essential for microautophagy. 4 However, in the alkane-utilizing yeast Yarrowia lipolytica, it is not required for pexophagy.…”

Section: Introductionmentioning

confidence: 99%

Atg26 is Not Involved in Autophagy-Related Pathways inSaccharomyces cerevisiae

Cao¹,

Klionsky²

2007

Autophagy

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“…The sterol glucosyltransferase Atg26 is also crucial for the generation of the MIPA (Oku et al 2003). Upon micropexophagy induction, the synthesis of phosphatidylinositol-4-phosphate at the site where the MIPA will emerge leads to the recruitment of Atg26 through its GRAM domain, which specifically binds to this lipid, and permits the local production of ergosterol glucoside (Oku et al 2003;Yamashita et al 2006). The function of this molecule in micropexophagy, however, is unclear and it appears to be essential only for glucose-induced micropexophagy, but not when the same pathway is triggered by oleate or amine (Nazarko et al 2007).…”

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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“…Therefore, we examined the trafficking of Atg9p and Atg11p, and we showed that their trafficking to the sequestering membranes was unaffected by the Sar1p mutants. The MIPA assembles from the PAS or initiation complex, a structure that contains Atg8p and Atg17p Yamashita et al, 2006). The formation of the MIPA is influenced by many Atg proteins, including Atg8p and Atg26p and the availability of lipids such as PE and phosphatidylinositol 4Ј-monophosphate (PI4P) (Yamashita et al, 2007).…”

Section: Role Of Sar1p In Micropexophagymentioning

confidence: 99%

The Membrane Dynamics of Pexophagy Are Influenced by Sar1p inPichia pastoris

Schröder

Ortiz

Dunn

2008

MBoC

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Several Sec proteins including a guanosine diphosphate/guanosine triphosphate exchange factor for Sar1p have been implicated in autophagy. In this study, we investigated the role of Sar1p in pexophagy by expressing dominant-negative mutant forms of Sar1p in Pichia pastoris. When expressing sar1pT34N or sar1pH79G, starvation-induced autophagy, glucose-induced micropexophagy, and ethanol-induced macropexophagy are dramatically suppressed. These Sar1p mutants did not affect the initiation or expansion of the sequestering membranes nor the trafficking of Atg11p and Atg9p to these membranes during micropexophagy. However, the lipidation of Atg8p and assembly of the micropexophagic membrane apparatus, which are essential to complete the incorporation of the peroxisomes into the degradative vacuole, were inhibited when either Sar1p mutant protein was expressed. During macropexophagy, the expression of sar1pT34N inhibited the formation of the pexophagosome, whereas sar1pH79G suppressed the delivery of the peroxisome from the pexophagosome to the vacuole. The pexophagosome contained Atg8p in wild-type cells, but in cells expressing sar1pH79G these organelles contain both Atg8p and endoplasmic reticulum components as visualized by DsRFP-HDEL. Our results demonstrate key roles for Sar1p in both micro-and macropexophagy.

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PI4P-signaling pathway for the synthesis of a nascent membrane structure in selective autophagy

Cited by 78 publications

References 31 publications

Atg26 is Not Involved in Autophagy-Related Pathways inSaccharomyces cerevisiae

Atg26 is Not Involved in Autophagy-Related Pathways inSaccharomyces cerevisiae

Autophagic Processes in Yeast: Mechanism, Machinery and Regulation

The Membrane Dynamics of Pexophagy Are Influenced by Sar1p inPichia pastoris

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