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ATG5 cancer mutations and alternative mRNA splicing reveal a conjugation switch that regulates ATG12–ATG5-ATG16L1 complex assembly and autophagy
Autophagy is critical for maintaining cellular homeostasis during times of stress, and is thought to play important roles in both tumorigenesis and tumor cell survival. Formation of autophagosomes, which mediate delivery of cytoplasmic cargo to lysosomes, requires multiple autophagy-related (ATG) pr...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Nature Publishing Group UK
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6796855/ https://www.ncbi.nlm.nih.gov/pubmed/31636955 http://dx.doi.org/10.1038/s41421-019-0110-1 |
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author | Wible, Daric J. Chao, Hsueh-Ping Tang, Dean G. Bratton, Shawn B. |
author_facet | Wible, Daric J. Chao, Hsueh-Ping Tang, Dean G. Bratton, Shawn B. |
author_sort | Wible, Daric J. |
collection | PubMed |
description | Autophagy is critical for maintaining cellular homeostasis during times of stress, and is thought to play important roles in both tumorigenesis and tumor cell survival. Formation of autophagosomes, which mediate delivery of cytoplasmic cargo to lysosomes, requires multiple autophagy-related (ATG) protein complexes, including the ATG12–ATG5-ATG16L1 complex. Herein, we report that a molecular ATG5 “conjugation switch”, comprised of competing ATG12 and ubiquitin conjugation reactions, integrates ATG12–ATG5-ATG16L1 complex assembly with protein quality control of its otherwise highly unstable subunits. This conjugation switch is tightly regulated by ATG16L1, which binds to free ATG5 and mutually protects both proteins from ubiquitin conjugation and proteasomal degradation, thereby instead promoting the irreversible conjugation of ATG12 to ATG5. The resulting ATG12–ATG5 conjugate, in turn, displays enhanced affinity for ATG16L1 and thus fully stabilizes the ATG12–ATG5-ATG16L1 complex. Most importantly, we find in multiple tumor types that ATG5 somatic mutations and alternative mRNA splicing specifically disrupt the ATG16L1-binding pocket in ATG5 and impair the essential ATG5-ATG16L1 interactions that are initially required for ATG12–ATG5 conjugation. Finally, we provide evidence that ATG16L2, which is overexpressed in several cancers relative to ATG16L1, hijacks the conjugation switch by competing with ATG16L1 for binding to ATG5. While ATG16L2 stabilizes ATG5 and enables ATG12–ATG5 conjugation, this endogenous dominant-negative inhibitor simultaneously displaces ATG16L1, resulting in its proteasomal degradation and a block in autophagy. Thus, collectively, our findings provide novel insights into ATG12–ATG5-ATG16L1 complex assembly and reveal multiple mechanisms wherein dysregulation of the ATG5 conjugation switch inhibits autophagy. |
format | Online Article Text |
id | pubmed-6796855 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | Nature Publishing Group UK |
record_format | MEDLINE/PubMed |
spelling | pubmed-67968552019-10-21 ATG5 cancer mutations and alternative mRNA splicing reveal a conjugation switch that regulates ATG12–ATG5-ATG16L1 complex assembly and autophagy Wible, Daric J. Chao, Hsueh-Ping Tang, Dean G. Bratton, Shawn B. Cell Discov Article Autophagy is critical for maintaining cellular homeostasis during times of stress, and is thought to play important roles in both tumorigenesis and tumor cell survival. Formation of autophagosomes, which mediate delivery of cytoplasmic cargo to lysosomes, requires multiple autophagy-related (ATG) protein complexes, including the ATG12–ATG5-ATG16L1 complex. Herein, we report that a molecular ATG5 “conjugation switch”, comprised of competing ATG12 and ubiquitin conjugation reactions, integrates ATG12–ATG5-ATG16L1 complex assembly with protein quality control of its otherwise highly unstable subunits. This conjugation switch is tightly regulated by ATG16L1, which binds to free ATG5 and mutually protects both proteins from ubiquitin conjugation and proteasomal degradation, thereby instead promoting the irreversible conjugation of ATG12 to ATG5. The resulting ATG12–ATG5 conjugate, in turn, displays enhanced affinity for ATG16L1 and thus fully stabilizes the ATG12–ATG5-ATG16L1 complex. Most importantly, we find in multiple tumor types that ATG5 somatic mutations and alternative mRNA splicing specifically disrupt the ATG16L1-binding pocket in ATG5 and impair the essential ATG5-ATG16L1 interactions that are initially required for ATG12–ATG5 conjugation. Finally, we provide evidence that ATG16L2, which is overexpressed in several cancers relative to ATG16L1, hijacks the conjugation switch by competing with ATG16L1 for binding to ATG5. While ATG16L2 stabilizes ATG5 and enables ATG12–ATG5 conjugation, this endogenous dominant-negative inhibitor simultaneously displaces ATG16L1, resulting in its proteasomal degradation and a block in autophagy. Thus, collectively, our findings provide novel insights into ATG12–ATG5-ATG16L1 complex assembly and reveal multiple mechanisms wherein dysregulation of the ATG5 conjugation switch inhibits autophagy. Nature Publishing Group UK 2019-08-27 /pmc/articles/PMC6796855/ /pubmed/31636955 http://dx.doi.org/10.1038/s41421-019-0110-1 Text en © The Author(s) 2019 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. |
spellingShingle | Article Wible, Daric J. Chao, Hsueh-Ping Tang, Dean G. Bratton, Shawn B. ATG5 cancer mutations and alternative mRNA splicing reveal a conjugation switch that regulates ATG12–ATG5-ATG16L1 complex assembly and autophagy |
title | ATG5 cancer mutations and alternative mRNA splicing reveal a conjugation switch that regulates ATG12–ATG5-ATG16L1 complex assembly and autophagy |
title_full | ATG5 cancer mutations and alternative mRNA splicing reveal a conjugation switch that regulates ATG12–ATG5-ATG16L1 complex assembly and autophagy |
title_fullStr | ATG5 cancer mutations and alternative mRNA splicing reveal a conjugation switch that regulates ATG12–ATG5-ATG16L1 complex assembly and autophagy |
title_full_unstemmed | ATG5 cancer mutations and alternative mRNA splicing reveal a conjugation switch that regulates ATG12–ATG5-ATG16L1 complex assembly and autophagy |
title_short | ATG5 cancer mutations and alternative mRNA splicing reveal a conjugation switch that regulates ATG12–ATG5-ATG16L1 complex assembly and autophagy |
title_sort | atg5 cancer mutations and alternative mrna splicing reveal a conjugation switch that regulates atg12–atg5-atg16l1 complex assembly and autophagy |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6796855/ https://www.ncbi.nlm.nih.gov/pubmed/31636955 http://dx.doi.org/10.1038/s41421-019-0110-1 |
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