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BiP Availability Distinguishes States of Homeostasis and Stress in the Endoplasmic Reticulum of Living Cells

Accumulation of misfolded secretory proteins causes cellular stress and induces the endoplasmic reticulum (ER) stress pathway, the unfolded protein response (UPR). Although the UPR has been extensively studied, little is known about the molecular changes that distinguish the homeostatic and stressed...

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Detalles Bibliográficos
Autores principales: Lai, Chun Wei, Aronson, Deborah E., Snapp, Erik Lee
Formato: Texto
Lenguaje:English
Publicado: The American Society for Cell Biology 2010
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2883936/
https://www.ncbi.nlm.nih.gov/pubmed/20410136
http://dx.doi.org/10.1091/mbc.E09-12-1066
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author Lai, Chun Wei
Aronson, Deborah E.
Snapp, Erik Lee
author_facet Lai, Chun Wei
Aronson, Deborah E.
Snapp, Erik Lee
author_sort Lai, Chun Wei
collection PubMed
description Accumulation of misfolded secretory proteins causes cellular stress and induces the endoplasmic reticulum (ER) stress pathway, the unfolded protein response (UPR). Although the UPR has been extensively studied, little is known about the molecular changes that distinguish the homeostatic and stressed ER. The increase in levels of misfolded proteins and formation of complexes with chaperones during ER stress are predicted to further crowd the already crowded ER lumen. Surprisingly, using live cell fluorescence microscopy and an inert ER reporter, we find the crowdedness of stressed ER, treated acutely with tunicamycin or DTT, either is comparable to homeostasis or significantly decreases in multiple cell types. In contrast, photobleaching experiments revealed a GFP-tagged variant of the ER chaperone BiP rapidly undergoes a reversible quantitative decrease in diffusion as misfolded proteins accumulate. BiP mobility is sensitive to exceptionally low levels of misfolded protein stressors and can detect intermediate states of BiP availability. Decreased BiP availability temporally correlates with UPR markers, but restoration of BiP availability correlates less well. Thus, BiP availability represents a novel and powerful tool for reporting global secretory protein misfolding levels and investigating the molecular events of ER stress in single cells, independent of traditional UPR markers.
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spelling pubmed-28839362010-08-30 BiP Availability Distinguishes States of Homeostasis and Stress in the Endoplasmic Reticulum of Living Cells Lai, Chun Wei Aronson, Deborah E. Snapp, Erik Lee Mol Biol Cell Articles Accumulation of misfolded secretory proteins causes cellular stress and induces the endoplasmic reticulum (ER) stress pathway, the unfolded protein response (UPR). Although the UPR has been extensively studied, little is known about the molecular changes that distinguish the homeostatic and stressed ER. The increase in levels of misfolded proteins and formation of complexes with chaperones during ER stress are predicted to further crowd the already crowded ER lumen. Surprisingly, using live cell fluorescence microscopy and an inert ER reporter, we find the crowdedness of stressed ER, treated acutely with tunicamycin or DTT, either is comparable to homeostasis or significantly decreases in multiple cell types. In contrast, photobleaching experiments revealed a GFP-tagged variant of the ER chaperone BiP rapidly undergoes a reversible quantitative decrease in diffusion as misfolded proteins accumulate. BiP mobility is sensitive to exceptionally low levels of misfolded protein stressors and can detect intermediate states of BiP availability. Decreased BiP availability temporally correlates with UPR markers, but restoration of BiP availability correlates less well. Thus, BiP availability represents a novel and powerful tool for reporting global secretory protein misfolding levels and investigating the molecular events of ER stress in single cells, independent of traditional UPR markers. The American Society for Cell Biology 2010-06-15 /pmc/articles/PMC2883936/ /pubmed/20410136 http://dx.doi.org/10.1091/mbc.E09-12-1066 Text en © 2010 by The American Society for Cell Biology
spellingShingle Articles
Lai, Chun Wei
Aronson, Deborah E.
Snapp, Erik Lee
BiP Availability Distinguishes States of Homeostasis and Stress in the Endoplasmic Reticulum of Living Cells
title BiP Availability Distinguishes States of Homeostasis and Stress in the Endoplasmic Reticulum of Living Cells
title_full BiP Availability Distinguishes States of Homeostasis and Stress in the Endoplasmic Reticulum of Living Cells
title_fullStr BiP Availability Distinguishes States of Homeostasis and Stress in the Endoplasmic Reticulum of Living Cells
title_full_unstemmed BiP Availability Distinguishes States of Homeostasis and Stress in the Endoplasmic Reticulum of Living Cells
title_short BiP Availability Distinguishes States of Homeostasis and Stress in the Endoplasmic Reticulum of Living Cells
title_sort bip availability distinguishes states of homeostasis and stress in the endoplasmic reticulum of living cells
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2883936/
https://www.ncbi.nlm.nih.gov/pubmed/20410136
http://dx.doi.org/10.1091/mbc.E09-12-1066
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