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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...
Autores principales: | , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2013
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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. |
format | Online Article Text |
id | pubmed-3789715 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2013 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
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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