Continued 26S proteasome dysfunction in mouse brain cortical neurons impairs autophagy and the Keap1-Nrf2 oxidative defence pathway

Aslihan Ugun-Klusek, Michael H. Tatham, Jamal Elkharaz, Dumitru Constantin-Teodosiu, Karen Lawler, Hala Mohamed, Simon M. L. Paine, Glen Anderson, R. John Mayer, James Lowe, E. Ellen Billett, Lynn Bedford (Lead / Corresponding author)

Research output: Contribution to journalArticle

8 Citations (Scopus)
85 Downloads (Pure)

Abstract

The ubiquitin-proteasome system (UPS) and macroautophagy (autophagy) are central to normal proteostasis and interdependent in that autophagy is known to compensate for the UPS to alleviate ensuing proteotoxic stress that impairs cell function. UPS and autophagy dysfunctions are believed to have a major role in the pathomechanisms of neurodegenerative disease. Here we show that continued 26S proteasome dysfunction in mouse brain cortical neurons causes paranuclear accumulation of fragmented dysfunctional mitochondria, associated with earlier recruitment of Parkin and lysine 48-linked ubiquitination of mitochondrial outer membrane (MOM) proteins, including Mitofusin-2. Early events also include phosphorylation of p62/SQSTM1 (p62) and increased optineurin, as well as autophagosomal LC3B and removal of some mitochondria, supporting the induction of selective autophagy. Inhibition of the degradation of ubiquitinated MOM proteins with continued 26S proteasome dysfunction at later stages may impede efficient mitophagy. However, continued 26S proteasome dysfunction also decreases the levels of essential autophagy proteins ATG9 and LC3B, which is characterised by decreases in their gene expression, ultimately leading to impaired autophagy. Intriguingly, serine 351 phosphorylation of p62 did not enhance its binding to Keap1 or stabilise the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor in this neuronal context. Nrf2 protein levels were markedly decreased despite transcriptional activation of the Nrf2 gene. Our study reveals novel insights into the interplay between the UPS and autophagy in neurons and is imperative to understanding neurodegenerative disease where long-term proteasome inhibition has been implicated.

Original languageEnglish
Article numbere2531
Pages (from-to)1-12
Number of pages12
JournalCell Death and Disease
Volume8
Early online date5 Jan 2017
DOIs
Publication statusPublished - Jan 2017

Fingerprint

Autophagy
Proteasome Endopeptidase Complex
Neurons
Ubiquitin
Brain
Neurodegenerative Diseases
Mitochondria
Membrane Proteins
Mitochondrial Degradation
Phosphorylation
Ubiquitination
ATP dependent 26S protease
Serine
Transcriptional Activation
Lysine
Proteins
Transcription Factors
Gene Expression
Genes

Cite this

Ugun-Klusek, Aslihan ; Tatham, Michael H. ; Elkharaz, Jamal ; Constantin-Teodosiu, Dumitru ; Lawler, Karen ; Mohamed, Hala ; Paine, Simon M. L. ; Anderson, Glen ; John Mayer, R. ; Lowe, James ; Ellen Billett, E. ; Bedford, Lynn. / Continued 26S proteasome dysfunction in mouse brain cortical neurons impairs autophagy and the Keap1-Nrf2 oxidative defence pathway. In: Cell Death and Disease. 2017 ; Vol. 8. pp. 1-12.
@article{2ec8a951fc624829bde5da807a8cd09a,
title = "Continued 26S proteasome dysfunction in mouse brain cortical neurons impairs autophagy and the Keap1-Nrf2 oxidative defence pathway",
abstract = "The ubiquitin-proteasome system (UPS) and macroautophagy (autophagy) are central to normal proteostasis and interdependent in that autophagy is known to compensate for the UPS to alleviate ensuing proteotoxic stress that impairs cell function. UPS and autophagy dysfunctions are believed to have a major role in the pathomechanisms of neurodegenerative disease. Here we show that continued 26S proteasome dysfunction in mouse brain cortical neurons causes paranuclear accumulation of fragmented dysfunctional mitochondria, associated with earlier recruitment of Parkin and lysine 48-linked ubiquitination of mitochondrial outer membrane (MOM) proteins, including Mitofusin-2. Early events also include phosphorylation of p62/SQSTM1 (p62) and increased optineurin, as well as autophagosomal LC3B and removal of some mitochondria, supporting the induction of selective autophagy. Inhibition of the degradation of ubiquitinated MOM proteins with continued 26S proteasome dysfunction at later stages may impede efficient mitophagy. However, continued 26S proteasome dysfunction also decreases the levels of essential autophagy proteins ATG9 and LC3B, which is characterised by decreases in their gene expression, ultimately leading to impaired autophagy. Intriguingly, serine 351 phosphorylation of p62 did not enhance its binding to Keap1 or stabilise the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor in this neuronal context. Nrf2 protein levels were markedly decreased despite transcriptional activation of the Nrf2 gene. Our study reveals novel insights into the interplay between the UPS and autophagy in neurons and is imperative to understanding neurodegenerative disease where long-term proteasome inhibition has been implicated.",
author = "Aslihan Ugun-Klusek and Tatham, {Michael H.} and Jamal Elkharaz and Dumitru Constantin-Teodosiu and Karen Lawler and Hala Mohamed and Paine, {Simon M. L.} and Glen Anderson and {John Mayer}, R. and James Lowe and {Ellen Billett}, E. and Lynn Bedford",
note = "This work was supported by Parkinson’s UK (LB; F-0702), Neuroscience Support Group at Queen’s Medical Centre (LB; Z53605) and through a Cancer Research UK programme grant (MHT; C434/A13067).",
year = "2017",
month = "1",
doi = "10.1038/cddis.2016.443",
language = "English",
volume = "8",
pages = "1--12",
journal = "Cell Death and Disease",
issn = "2041-4889",
publisher = "Nature Publishing Group",

}

Ugun-Klusek, A, Tatham, MH, Elkharaz, J, Constantin-Teodosiu, D, Lawler, K, Mohamed, H, Paine, SML, Anderson, G, John Mayer, R, Lowe, J, Ellen Billett, E & Bedford, L 2017, 'Continued 26S proteasome dysfunction in mouse brain cortical neurons impairs autophagy and the Keap1-Nrf2 oxidative defence pathway', Cell Death and Disease, vol. 8, e2531, pp. 1-12. https://doi.org/10.1038/cddis.2016.443

Continued 26S proteasome dysfunction in mouse brain cortical neurons impairs autophagy and the Keap1-Nrf2 oxidative defence pathway. / Ugun-Klusek, Aslihan; Tatham, Michael H.; Elkharaz, Jamal; Constantin-Teodosiu, Dumitru; Lawler, Karen; Mohamed, Hala; Paine, Simon M. L.; Anderson, Glen; John Mayer, R.; Lowe, James; Ellen Billett, E.; Bedford, Lynn (Lead / Corresponding author).

In: Cell Death and Disease, Vol. 8, e2531, 01.2017, p. 1-12.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Continued 26S proteasome dysfunction in mouse brain cortical neurons impairs autophagy and the Keap1-Nrf2 oxidative defence pathway

AU - Ugun-Klusek, Aslihan

AU - Tatham, Michael H.

AU - Elkharaz, Jamal

AU - Constantin-Teodosiu, Dumitru

AU - Lawler, Karen

AU - Mohamed, Hala

AU - Paine, Simon M. L.

AU - Anderson, Glen

AU - John Mayer, R.

AU - Lowe, James

AU - Ellen Billett, E.

AU - Bedford, Lynn

N1 - This work was supported by Parkinson’s UK (LB; F-0702), Neuroscience Support Group at Queen’s Medical Centre (LB; Z53605) and through a Cancer Research UK programme grant (MHT; C434/A13067).

PY - 2017/1

Y1 - 2017/1

N2 - The ubiquitin-proteasome system (UPS) and macroautophagy (autophagy) are central to normal proteostasis and interdependent in that autophagy is known to compensate for the UPS to alleviate ensuing proteotoxic stress that impairs cell function. UPS and autophagy dysfunctions are believed to have a major role in the pathomechanisms of neurodegenerative disease. Here we show that continued 26S proteasome dysfunction in mouse brain cortical neurons causes paranuclear accumulation of fragmented dysfunctional mitochondria, associated with earlier recruitment of Parkin and lysine 48-linked ubiquitination of mitochondrial outer membrane (MOM) proteins, including Mitofusin-2. Early events also include phosphorylation of p62/SQSTM1 (p62) and increased optineurin, as well as autophagosomal LC3B and removal of some mitochondria, supporting the induction of selective autophagy. Inhibition of the degradation of ubiquitinated MOM proteins with continued 26S proteasome dysfunction at later stages may impede efficient mitophagy. However, continued 26S proteasome dysfunction also decreases the levels of essential autophagy proteins ATG9 and LC3B, which is characterised by decreases in their gene expression, ultimately leading to impaired autophagy. Intriguingly, serine 351 phosphorylation of p62 did not enhance its binding to Keap1 or stabilise the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor in this neuronal context. Nrf2 protein levels were markedly decreased despite transcriptional activation of the Nrf2 gene. Our study reveals novel insights into the interplay between the UPS and autophagy in neurons and is imperative to understanding neurodegenerative disease where long-term proteasome inhibition has been implicated.

AB - The ubiquitin-proteasome system (UPS) and macroautophagy (autophagy) are central to normal proteostasis and interdependent in that autophagy is known to compensate for the UPS to alleviate ensuing proteotoxic stress that impairs cell function. UPS and autophagy dysfunctions are believed to have a major role in the pathomechanisms of neurodegenerative disease. Here we show that continued 26S proteasome dysfunction in mouse brain cortical neurons causes paranuclear accumulation of fragmented dysfunctional mitochondria, associated with earlier recruitment of Parkin and lysine 48-linked ubiquitination of mitochondrial outer membrane (MOM) proteins, including Mitofusin-2. Early events also include phosphorylation of p62/SQSTM1 (p62) and increased optineurin, as well as autophagosomal LC3B and removal of some mitochondria, supporting the induction of selective autophagy. Inhibition of the degradation of ubiquitinated MOM proteins with continued 26S proteasome dysfunction at later stages may impede efficient mitophagy. However, continued 26S proteasome dysfunction also decreases the levels of essential autophagy proteins ATG9 and LC3B, which is characterised by decreases in their gene expression, ultimately leading to impaired autophagy. Intriguingly, serine 351 phosphorylation of p62 did not enhance its binding to Keap1 or stabilise the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor in this neuronal context. Nrf2 protein levels were markedly decreased despite transcriptional activation of the Nrf2 gene. Our study reveals novel insights into the interplay between the UPS and autophagy in neurons and is imperative to understanding neurodegenerative disease where long-term proteasome inhibition has been implicated.

U2 - 10.1038/cddis.2016.443

DO - 10.1038/cddis.2016.443

M3 - Article

VL - 8

SP - 1

EP - 12

JO - Cell Death and Disease

JF - Cell Death and Disease

SN - 2041-4889

M1 - e2531

ER -