TFEB/Mitf links impaired nuclear import to autophagolysosomal dysfunction in C9-ALS
Disrupted nucleocytoplasmic transport (NCT) has been implicated in neurodegenerative disease pathogenesis; however, the mechanisms by which disrupted NCT causes neurodegeneration remain unclear. In a Drosophila screen, we identified ref(2)P/p62, a key regulator of autophagy, as a potent suppressor of neurodegeneration caused by the GGGGCC hexanucleotide repeat expansion (G4C2 HRE) in C9orf72 that causes amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). We found that p62 is increased and forms ubiquitinated aggregates due to decreased autophagic cargo degradation. Immunofluorescence and electron microscopy of Drosophila tissues demonstrate an accumulation of lysosome-like organelles that precedes neurodegeneration. These phenotypes are partially caused by cytoplasmic mislocalization of Mitf/TFEB, a key transcriptional regulator of autophagolysosomal function. Additionally, TFEB is mislocalized and downregulated in human cells expressing GGGGCC repeats and in C9-ALS patient motor cortex. Our data suggest that the C9orf72-HRE impairs Mitf/TFEB nuclear import, thereby disrupting autophagy and exacerbating proteostasis defects in C9-ALS/FTD.
All data generated or analysed during this study are included in the manuscript and supporting files.
Article and author information
National Institute of Neurological Disorders and Stroke (R01NS082563,R01NS094239,P30NS050274,F31NS100401)
- Thomas E Lloyd
Amyotrophic Lateral Sclerosis Association (17-IIP-370)
- Thomas E Lloyd
National Institute of General Medical Sciences (P40OD018537)
- Hugo J Bellen
Howard Hughes Medical Institute
- Hugo J Bellen
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Human subjects: The use of human tissue and associated decedents' demographic information was approved by the Johns Hopkins University Institutional Review Board and ethics committee (HIPAA Form 5 exemption, Application 11-02-10-01RD) and from the Ravitz Laboratory (UCSD) through the Target ALS Consortium.
- Harry T Orr, University of Minnesota, United States
- Received: May 28, 2020
- Accepted: December 9, 2020
- Accepted Manuscript published: December 10, 2020 (version 1)
- Version of Record published: December 23, 2020 (version 2)
- Version of Record updated: December 31, 2020 (version 3)
© 2020, Cunningham et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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