Cargando…

Novel Insights into the Cellular Localization and Regulation of the Autophagosomal Proteins LC3A, LC3B and LC3C

Macroautophagy is a conserved degradative process for maintaining cellular homeostasis and plays a key role in aging and various human disorders. The microtubule-associated protein 1A/1B light chain 3B (MAP1LC3B or LC3B) is commonly analyzed as a key marker for autophagosomes and as a proxy for auto...

Descripción completa

Detalles Bibliográficos
Autores principales: Baeken, Marius W., Weckmann, Katja, Diefenthäler, Philip, Schulte, Jan, Yusifli, Kamran, Moosmann, Bernd, Behl, Christian, Hajieva, Parvana
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7603224/
https://www.ncbi.nlm.nih.gov/pubmed/33081014
http://dx.doi.org/10.3390/cells9102315
_version_ 1783603874234368000
author Baeken, Marius W.
Weckmann, Katja
Diefenthäler, Philip
Schulte, Jan
Yusifli, Kamran
Moosmann, Bernd
Behl, Christian
Hajieva, Parvana
author_facet Baeken, Marius W.
Weckmann, Katja
Diefenthäler, Philip
Schulte, Jan
Yusifli, Kamran
Moosmann, Bernd
Behl, Christian
Hajieva, Parvana
author_sort Baeken, Marius W.
collection PubMed
description Macroautophagy is a conserved degradative process for maintaining cellular homeostasis and plays a key role in aging and various human disorders. The microtubule-associated protein 1A/1B light chain 3B (MAP1LC3B or LC3B) is commonly analyzed as a key marker for autophagosomes and as a proxy for autophagic flux. Three paralogues of the LC3 gene exist in humans: LC3A, LC3B and LC3C. The molecular function, regulation and cellular localization of LC3A and LC3C have not been investigated frequently, even if a similar function to that described for LC3B appears likely. Here, we have selectively decapacitated LC3B by three separate strategies in primary human fibroblasts and analyzed the evoked effects on LC3A, LC3B and LC3C in terms of their cellular distribution and co-localization with p62, a ubiquitin and autophagy receptor. First, treatment with pharmacological sirtuin 1 (SIRT1) inhibitors to prevent the translocation of LC3B from the nucleus into the cytosol induced an increase in cytosolic LC3C, a heightened co-localization of LC3C with p62, and an increase LC3C-dependent autophagic flux as assessed by protein lipidation. Cytosolic LC3A, however, was moderately reduced, but also more co-localized with p62. Second, siRNA-based knock-down of SIRT1 broadly reproduced these findings and increased the co-localization of LC3A and particularly LC3C with p62 in presumed autophagosomes. These effects resembled the effects of pharmacological sirtuin inhibition under normal and starvation conditions. Third, siRNA-based knock-down of total LC3B in cytosol and nucleus also induced a redistribution of LC3C as if to replace LC3B in the nucleus, but only moderately affected LC3A. Total protein expression of LC3A, LC3B, LC3C, GABARAP and GABARAP-L1 following LC3B decapacitation was unaltered. Our data indicate that nuclear trapping and other causes of LC3B functional loss in the cytosol are buffered by LC3A and actively compensated by LC3C, but not by GABARAPs. The biological relevance of the potential functional compensation of LC3B decapacitation by LC3C and LC3A warrants further study.
format Online
Article
Text
id pubmed-7603224
institution National Center for Biotechnology Information
language English
publishDate 2020
publisher MDPI
record_format MEDLINE/PubMed
spelling pubmed-76032242020-11-01 Novel Insights into the Cellular Localization and Regulation of the Autophagosomal Proteins LC3A, LC3B and LC3C Baeken, Marius W. Weckmann, Katja Diefenthäler, Philip Schulte, Jan Yusifli, Kamran Moosmann, Bernd Behl, Christian Hajieva, Parvana Cells Article Macroautophagy is a conserved degradative process for maintaining cellular homeostasis and plays a key role in aging and various human disorders. The microtubule-associated protein 1A/1B light chain 3B (MAP1LC3B or LC3B) is commonly analyzed as a key marker for autophagosomes and as a proxy for autophagic flux. Three paralogues of the LC3 gene exist in humans: LC3A, LC3B and LC3C. The molecular function, regulation and cellular localization of LC3A and LC3C have not been investigated frequently, even if a similar function to that described for LC3B appears likely. Here, we have selectively decapacitated LC3B by three separate strategies in primary human fibroblasts and analyzed the evoked effects on LC3A, LC3B and LC3C in terms of their cellular distribution and co-localization with p62, a ubiquitin and autophagy receptor. First, treatment with pharmacological sirtuin 1 (SIRT1) inhibitors to prevent the translocation of LC3B from the nucleus into the cytosol induced an increase in cytosolic LC3C, a heightened co-localization of LC3C with p62, and an increase LC3C-dependent autophagic flux as assessed by protein lipidation. Cytosolic LC3A, however, was moderately reduced, but also more co-localized with p62. Second, siRNA-based knock-down of SIRT1 broadly reproduced these findings and increased the co-localization of LC3A and particularly LC3C with p62 in presumed autophagosomes. These effects resembled the effects of pharmacological sirtuin inhibition under normal and starvation conditions. Third, siRNA-based knock-down of total LC3B in cytosol and nucleus also induced a redistribution of LC3C as if to replace LC3B in the nucleus, but only moderately affected LC3A. Total protein expression of LC3A, LC3B, LC3C, GABARAP and GABARAP-L1 following LC3B decapacitation was unaltered. Our data indicate that nuclear trapping and other causes of LC3B functional loss in the cytosol are buffered by LC3A and actively compensated by LC3C, but not by GABARAPs. The biological relevance of the potential functional compensation of LC3B decapacitation by LC3C and LC3A warrants further study. MDPI 2020-10-18 /pmc/articles/PMC7603224/ /pubmed/33081014 http://dx.doi.org/10.3390/cells9102315 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Baeken, Marius W.
Weckmann, Katja
Diefenthäler, Philip
Schulte, Jan
Yusifli, Kamran
Moosmann, Bernd
Behl, Christian
Hajieva, Parvana
Novel Insights into the Cellular Localization and Regulation of the Autophagosomal Proteins LC3A, LC3B and LC3C
title Novel Insights into the Cellular Localization and Regulation of the Autophagosomal Proteins LC3A, LC3B and LC3C
title_full Novel Insights into the Cellular Localization and Regulation of the Autophagosomal Proteins LC3A, LC3B and LC3C
title_fullStr Novel Insights into the Cellular Localization and Regulation of the Autophagosomal Proteins LC3A, LC3B and LC3C
title_full_unstemmed Novel Insights into the Cellular Localization and Regulation of the Autophagosomal Proteins LC3A, LC3B and LC3C
title_short Novel Insights into the Cellular Localization and Regulation of the Autophagosomal Proteins LC3A, LC3B and LC3C
title_sort novel insights into the cellular localization and regulation of the autophagosomal proteins lc3a, lc3b and lc3c
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7603224/
https://www.ncbi.nlm.nih.gov/pubmed/33081014
http://dx.doi.org/10.3390/cells9102315
work_keys_str_mv AT baekenmariusw novelinsightsintothecellularlocalizationandregulationoftheautophagosomalproteinslc3alc3bandlc3c
AT weckmannkatja novelinsightsintothecellularlocalizationandregulationoftheautophagosomalproteinslc3alc3bandlc3c
AT diefenthalerphilip novelinsightsintothecellularlocalizationandregulationoftheautophagosomalproteinslc3alc3bandlc3c
AT schultejan novelinsightsintothecellularlocalizationandregulationoftheautophagosomalproteinslc3alc3bandlc3c
AT yusiflikamran novelinsightsintothecellularlocalizationandregulationoftheautophagosomalproteinslc3alc3bandlc3c
AT moosmannbernd novelinsightsintothecellularlocalizationandregulationoftheautophagosomalproteinslc3alc3bandlc3c
AT behlchristian novelinsightsintothecellularlocalizationandregulationoftheautophagosomalproteinslc3alc3bandlc3c
AT hajievaparvana novelinsightsintothecellularlocalizationandregulationoftheautophagosomalproteinslc3alc3bandlc3c