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Regulation of Mammalian Autophagy by Class II and III PI 3-Kinases through PI3P Synthesis

Synthesis of phosphatidylinositol-3-phosphate (PI3P) by Vps34, a class III phosphatidylinositol 3-kinase (PI3K), is critical for the initial steps of autophagosome (AP) biogenesis. Although Vps34 is the sole source of PI3P in budding yeast, mammalian cells can produce PI3P through alternate pathways...

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Autores principales: Devereaux, Kelly, Dall’Armi, Claudia, Alcazar-Roman, Abel, Ogasawara, Yuta, Zhou, Xiang, Wang, Fan, Yamamoto, Akitsugu, De Camilli, Pietro, Di Paolo, Gilbert
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3789715/
https://www.ncbi.nlm.nih.gov/pubmed/24098492
http://dx.doi.org/10.1371/journal.pone.0076405
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author Devereaux, Kelly
Dall’Armi, Claudia
Alcazar-Roman, Abel
Ogasawara, Yuta
Zhou, Xiang
Wang, Fan
Yamamoto, Akitsugu
De Camilli, Pietro
Di Paolo, Gilbert
author_facet Devereaux, Kelly
Dall’Armi, Claudia
Alcazar-Roman, Abel
Ogasawara, Yuta
Zhou, Xiang
Wang, Fan
Yamamoto, Akitsugu
De Camilli, Pietro
Di Paolo, Gilbert
author_sort Devereaux, Kelly
collection PubMed
description Synthesis of phosphatidylinositol-3-phosphate (PI3P) by Vps34, a class III phosphatidylinositol 3-kinase (PI3K), is critical for the initial steps of autophagosome (AP) biogenesis. Although Vps34 is the sole source of PI3P in budding yeast, mammalian cells can produce PI3P through alternate pathways, including direct synthesis by the class II PI3Ks; however, the physiological relevance of these alternate pathways in the context of autophagy is unknown. Here we generated Vps34 knockout mouse embryonic fibroblasts (MEFs) and using a higher affinity 4x-FYVE finger PI3P-binding probe found a Vps34-independent pool of PI3P accounting for (~)35% of the total amount of this lipid species by biochemical analysis. Importantly, WIPI-1, an autophagy-relevant PI3P probe, still formed some puncta upon starvation-induced autophagy in Vps34 knockout MEFs. Additional characterization of autophagy by electron microscopy as well as protein degradation assays showed that while Vps34 is important for starvation-induced autophagy there is a significant component of functional autophagy occurring in the absence of Vps34. Given these findings, class II PI3Ks (α and β isoforms) were examined as potential positive regulators of autophagy. Depletion of class II PI3Ks reduced recruitment of WIPI-1 and LC3 to AP nucleation sites and caused an accumulation of the autophagy substrate, p62, which was exacerbated upon the concomitant ablation of Vps34. Our studies indicate that while Vps34 is the main PI3P source during autophagy, class II PI3Ks also significantly contribute to PI3P generation and regulate AP biogenesis.
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spelling pubmed-37897152013-10-04 Regulation of Mammalian Autophagy by Class II and III PI 3-Kinases through PI3P Synthesis Devereaux, Kelly Dall’Armi, Claudia Alcazar-Roman, Abel Ogasawara, Yuta Zhou, Xiang Wang, Fan Yamamoto, Akitsugu De Camilli, Pietro Di Paolo, Gilbert PLoS One Research Article Synthesis of phosphatidylinositol-3-phosphate (PI3P) by Vps34, a class III phosphatidylinositol 3-kinase (PI3K), is critical for the initial steps of autophagosome (AP) biogenesis. Although Vps34 is the sole source of PI3P in budding yeast, mammalian cells can produce PI3P through alternate pathways, including direct synthesis by the class II PI3Ks; however, the physiological relevance of these alternate pathways in the context of autophagy is unknown. Here we generated Vps34 knockout mouse embryonic fibroblasts (MEFs) and using a higher affinity 4x-FYVE finger PI3P-binding probe found a Vps34-independent pool of PI3P accounting for (~)35% of the total amount of this lipid species by biochemical analysis. Importantly, WIPI-1, an autophagy-relevant PI3P probe, still formed some puncta upon starvation-induced autophagy in Vps34 knockout MEFs. Additional characterization of autophagy by electron microscopy as well as protein degradation assays showed that while Vps34 is important for starvation-induced autophagy there is a significant component of functional autophagy occurring in the absence of Vps34. Given these findings, class II PI3Ks (α and β isoforms) were examined as potential positive regulators of autophagy. Depletion of class II PI3Ks reduced recruitment of WIPI-1 and LC3 to AP nucleation sites and caused an accumulation of the autophagy substrate, p62, which was exacerbated upon the concomitant ablation of Vps34. Our studies indicate that while Vps34 is the main PI3P source during autophagy, class II PI3Ks also significantly contribute to PI3P generation and regulate AP biogenesis. Public Library of Science 2013-10-03 /pmc/articles/PMC3789715/ /pubmed/24098492 http://dx.doi.org/10.1371/journal.pone.0076405 Text en © 2013 Devereaux et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Devereaux, Kelly
Dall’Armi, Claudia
Alcazar-Roman, Abel
Ogasawara, Yuta
Zhou, Xiang
Wang, Fan
Yamamoto, Akitsugu
De Camilli, Pietro
Di Paolo, Gilbert
Regulation of Mammalian Autophagy by Class II and III PI 3-Kinases through PI3P Synthesis
title Regulation of Mammalian Autophagy by Class II and III PI 3-Kinases through PI3P Synthesis
title_full Regulation of Mammalian Autophagy by Class II and III PI 3-Kinases through PI3P Synthesis
title_fullStr Regulation of Mammalian Autophagy by Class II and III PI 3-Kinases through PI3P Synthesis
title_full_unstemmed Regulation of Mammalian Autophagy by Class II and III PI 3-Kinases through PI3P Synthesis
title_short Regulation of Mammalian Autophagy by Class II and III PI 3-Kinases through PI3P Synthesis
title_sort regulation of mammalian autophagy by class ii and iii pi 3-kinases through pi3p synthesis
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3789715/
https://www.ncbi.nlm.nih.gov/pubmed/24098492
http://dx.doi.org/10.1371/journal.pone.0076405
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