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A PI3K-WIPI2 positive feedback loop allosterically activates LC3 lipidation in autophagy

Autophagy degrades cytoplasmic cargo by its delivery to lysosomes within double membrane autophagosomes. Synthesis of the phosphoinositide PI(3)P by the autophagic class III phosphatidylinositol-3 kinase complex I (PI3KC3-C1) and conjugation of ATG8/LC3 proteins to phagophore membranes by the ATG12–...

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Autores principales: Fracchiolla, Dorotea, Chang, Chunmei, Hurley, James H., Martens, Sascha
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Rockefeller University Press 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7337497/
https://www.ncbi.nlm.nih.gov/pubmed/32437499
http://dx.doi.org/10.1083/jcb.201912098
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author Fracchiolla, Dorotea
Chang, Chunmei
Hurley, James H.
Martens, Sascha
author_facet Fracchiolla, Dorotea
Chang, Chunmei
Hurley, James H.
Martens, Sascha
author_sort Fracchiolla, Dorotea
collection PubMed
description Autophagy degrades cytoplasmic cargo by its delivery to lysosomes within double membrane autophagosomes. Synthesis of the phosphoinositide PI(3)P by the autophagic class III phosphatidylinositol-3 kinase complex I (PI3KC3-C1) and conjugation of ATG8/LC3 proteins to phagophore membranes by the ATG12–ATG5-ATG16L1 (E3) complex are two critical steps in autophagosome biogenesis, connected by WIPI2. Here, we present a complete reconstitution of these events. On giant unilamellar vesicles (GUVs), LC3 lipidation is strictly dependent on the recruitment of WIPI2 that in turn depends on PI(3)P. Ectopically targeting E3 to membranes in the absence of WIPI2 is insufficient to support LC3 lipidation, demonstrating that WIPI2 allosterically activates the E3 complex. PI3KC3-C1 and WIPI2 mutually promote the recruitment of each other in a positive feedback loop. When both PI 3-kinase and LC3 lipidation reactions were performed simultaneously, positive feedback between PI3KC3-C1 and WIPI2 led to rapid LC3 lipidation with kinetics similar to that seen in cellular autophagosome formation.
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spelling pubmed-73374972020-07-16 A PI3K-WIPI2 positive feedback loop allosterically activates LC3 lipidation in autophagy Fracchiolla, Dorotea Chang, Chunmei Hurley, James H. Martens, Sascha J Cell Biol Article Autophagy degrades cytoplasmic cargo by its delivery to lysosomes within double membrane autophagosomes. Synthesis of the phosphoinositide PI(3)P by the autophagic class III phosphatidylinositol-3 kinase complex I (PI3KC3-C1) and conjugation of ATG8/LC3 proteins to phagophore membranes by the ATG12–ATG5-ATG16L1 (E3) complex are two critical steps in autophagosome biogenesis, connected by WIPI2. Here, we present a complete reconstitution of these events. On giant unilamellar vesicles (GUVs), LC3 lipidation is strictly dependent on the recruitment of WIPI2 that in turn depends on PI(3)P. Ectopically targeting E3 to membranes in the absence of WIPI2 is insufficient to support LC3 lipidation, demonstrating that WIPI2 allosterically activates the E3 complex. PI3KC3-C1 and WIPI2 mutually promote the recruitment of each other in a positive feedback loop. When both PI 3-kinase and LC3 lipidation reactions were performed simultaneously, positive feedback between PI3KC3-C1 and WIPI2 led to rapid LC3 lipidation with kinetics similar to that seen in cellular autophagosome formation. Rockefeller University Press 2020-05-21 /pmc/articles/PMC7337497/ /pubmed/32437499 http://dx.doi.org/10.1083/jcb.201912098 Text en © 2020 Fracchiolla et al. https://creativecommons.org/licenses/by/4.0/This article is available under a Creative Commons License (Attribution 4.0 International, as described at https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Fracchiolla, Dorotea
Chang, Chunmei
Hurley, James H.
Martens, Sascha
A PI3K-WIPI2 positive feedback loop allosterically activates LC3 lipidation in autophagy
title A PI3K-WIPI2 positive feedback loop allosterically activates LC3 lipidation in autophagy
title_full A PI3K-WIPI2 positive feedback loop allosterically activates LC3 lipidation in autophagy
title_fullStr A PI3K-WIPI2 positive feedback loop allosterically activates LC3 lipidation in autophagy
title_full_unstemmed A PI3K-WIPI2 positive feedback loop allosterically activates LC3 lipidation in autophagy
title_short A PI3K-WIPI2 positive feedback loop allosterically activates LC3 lipidation in autophagy
title_sort pi3k-wipi2 positive feedback loop allosterically activates lc3 lipidation in autophagy
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7337497/
https://www.ncbi.nlm.nih.gov/pubmed/32437499
http://dx.doi.org/10.1083/jcb.201912098
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