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Cholesterol Alters Mitophagy by Impairing Optineurin Recruitment and Lysosomal Clearance in Alzheimer’s Disease
Anna Colell
Institut d'Investigacions Biomèdiques de Barcelona (IIBB-CSIC)
Corresponding Author
ORCiD: https://orcid.org/0000-0001-5236-1834
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The most recent version of this article is available here.
Background: Emerging evidence indicates that impaired mitophagy-mediated clearance of defective mitochondria is a critical event in Alzheimer’s disease (AD) pathogenesis. Amyloid-beta (Aβ) metabolism and the microtubule-associated protein tau have been reported to regulate key components of the mitophagy machinery. However, the mechanisms that lead to mitophagy dysfunction in AD are not fully deciphered. We have previously shown that intraneuronal cholesterol accumulation can disrupt the autophagy flux, resulting in low Aβ clearance. In this study, we examine the impact of neuronal cholesterol changes on mitochondrial removal by autophagy.
Methods: Regulation of PINK1-parkin-mediated mitophagy was investigated in conditions of acute (in vitro) and chronic (in vivo) high cholesterol loading using cholesterol-enriched SH-SY5Y cells, cultured primary neurons from transgenic mice overexpressing active SREBF2 (sterol regulatory element binding factor 2), and mice of increasing age that express the amyloid precursor protein with the familial Alzheimer Swedish mutation (Mo/HuAPP695swe) and mutant presenilin 1 (PS1-dE9) together with active SREBF2.
Results: In cholesterol-enriched SH-SY5Y cells and cultured primary neurons, high intracellular cholesterol levels stimulated mitochondrial PINK1 accumulation and mitophagosomes formation triggered by Aβ while impairing lysosomal-mediated clearance. Antioxidant recovery of cholesterol-induced mitochondrial glutathione (GSH) depletion prevented mitophagosomes formation indicating mitochondrial ROS involvement. Interestingly, when brain cholesterol accumulated chronically in aged APP-PSEN1-SREBF2 mice the mitophagy flux was affected at the early steps of the pathway, with defective recruitment of the key autophagy receptor optineurin (OPTN). Sustained cholesterol-induced alterations in APP-PSEN1-SREBF2 mice promoted an age-dependent accumulation of OPTN into HDAC6-positive aggresomes, which disappeared after in vivo treatment with GSH ethyl ester (GSHee). The analyses in post-mortem brain tissues from individuals with AD confirmed these findings, showing OPTN in aggresome-like structures that correlated with high mitochondrial cholesterol levels in late AD stages.
Conclusions: Our data demonstrate that accumulation of intracellular cholesterol reduces the clearance of defective mitochondria and suggest recovery of the cholesterol homeostasis and the mitochondrial scavenging of ROS as potential therapeutic targets for AD.
Keywords
APP-PSEN1 mice, mitochondria, glutathione, oxidative stress, PINK1, parkin, optineurin, aggressomes
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Received 14 Oct, 2020
Reviewer #3 agreed
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Received 24 Sep, 2020
Reviewers invited
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Reviewer #1 agreed
On 24 Sep, 2020
Reviewer #2 agreed
On 24 Sep, 2020
Review #1 received
Received 24 Sep, 2020
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This preprint is under consideration at Molecular Neurodegeneration. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research article
Cholesterol Alters Mitophagy by Impairing Optineurin Recruitment and Lysosomal Clearance in Alzheimer’s Disease
Anna Colell
Institut d'Investigacions Biomèdiques de Barcelona (IIBB-CSIC)
Corresponding Author
ORCiD: https://orcid.org/0000-0001-5236-1834
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Under Review
No community comments so far
Review #1 received
Received 17 Feb, 2021
Reviewer #1 agreed
On 07 Feb, 2021
Editor assigned
On 03 Feb, 2021
Reviewers invited
Invitations sent on 03 Feb, 2021
Submission checks complete
On 03 Feb, 2021
Editor invited
On 03 Feb, 2021
Version 2
Posted 29 Dec, 2020
No comments provided
Editorial decision: Major revision
On 01 Jan, 2021
Review #2 received
Received 31 Dec, 2020
Reviewer #2 agreed
On 15 Dec, 2020
Review #1 received
Received 13 Dec, 2020
Editor assigned
On 11 Dec, 2020
Reviewers invited
Invitations sent on 11 Dec, 2020
Reviewer #1 agreed
On 11 Dec, 2020
Submission checks complete
On 11 Dec, 2020
Editor invited
On 11 Dec, 2020
No comments provided
Editorial decision: Major revision
On 15 Oct, 2020
Review #3 received
Received 14 Oct, 2020
Reviewer #3 agreed
On 30 Sep, 2020
Review #2 received
Received 24 Sep, 2020
Reviewers invited
Invitations sent on 24 Sep, 2020
Reviewer #1 agreed
On 24 Sep, 2020
Reviewer #2 agreed
On 24 Sep, 2020
Review #1 received
Received 24 Sep, 2020
Editor assigned
On 07 Sep, 2020
Submission checks complete
On 06 Sep, 2020
Editor invited
On 06 Sep, 2020
First submitted
On 01 Sep, 2020
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Molecular Genetics
License:
This work is licensed under a CC BY 4.0 License. Read Full License
The most recent version of this article is available here.
Background: Emerging evidence indicates that impaired mitophagy-mediated clearance of defective mitochondria is a critical event in Alzheimer’s disease (AD) pathogenesis. Amyloid-beta (Aβ) metabolism and the microtubule-associated protein tau have been reported to regulate key components of the mitophagy machinery. However, the mechanisms that lead to mitophagy dysfunction in AD are not fully deciphered. We have previously shown that intraneuronal cholesterol accumulation can disrupt the autophagy flux, resulting in low Aβ clearance. In this study, we examine the impact of neuronal cholesterol changes on mitochondrial removal by autophagy.
Methods: Regulation of PINK1-parkin-mediated mitophagy was investigated in conditions of acute (in vitro) and chronic (in vivo) high cholesterol loading using cholesterol-enriched SH-SY5Y cells, cultured primary neurons from transgenic mice overexpressing active SREBF2 (sterol regulatory element binding factor 2), and mice of increasing age that express the amyloid precursor protein with the familial Alzheimer Swedish mutation (Mo/HuAPP695swe) and mutant presenilin 1 (PS1-dE9) together with active SREBF2.
Results: In cholesterol-enriched SH-SY5Y cells and cultured primary neurons, high intracellular cholesterol levels stimulated mitochondrial PINK1 accumulation and mitophagosomes formation triggered by Aβ while impairing lysosomal-mediated clearance. Antioxidant recovery of cholesterol-induced mitochondrial glutathione (GSH) depletion prevented mitophagosomes formation indicating mitochondrial ROS involvement. Interestingly, when brain cholesterol accumulated chronically in aged APP-PSEN1-SREBF2 mice the mitophagy flux was affected at the early steps of the pathway, with defective recruitment of the key autophagy receptor optineurin (OPTN). Sustained cholesterol-induced alterations in APP-PSEN1-SREBF2 mice promoted an age-dependent accumulation of OPTN into HDAC6-positive aggresomes, which disappeared after in vivo treatment with GSH ethyl ester (GSHee). The analyses in post-mortem brain tissues from individuals with AD confirmed these findings, showing OPTN in aggresome-like structures that correlated with high mitochondrial cholesterol levels in late AD stages.
Conclusions: Our data demonstrate that accumulation of intracellular cholesterol reduces the clearance of defective mitochondria and suggest recovery of the cholesterol homeostasis and the mitochondrial scavenging of ROS as potential therapeutic targets for AD.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6