1
|
Zhang YJ, Jansen-West K, Xu YF, Gendron TF, Bieniek KF, Lin WL, Sasaguri H, Caulfield T, Hubbard J, Daughrity L, Chew J, Belzil VV, Prudencio M, Stankowski JN, Castanedes-Casey M, Whitelaw E, Ash PEA, DeTure M, Rademakers R, Boylan KB, Dickson DW, Petrucelli L. Aggregation-prone c9FTD/ALS poly(GA) RAN-translated proteins cause neurotoxicity by inducing ER stress. Acta Neuropathol 2014; 128:505-24. [PMID: 25173361 PMCID: PMC4159567 DOI: 10.1007/s00401-014-1336-5] [Citation(s) in RCA: 240] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Revised: 08/20/2014] [Accepted: 08/20/2014] [Indexed: 12/13/2022]
Abstract
The occurrence of repeat-associated non-ATG (RAN) translation, an atypical form of translation of expanded repeats that results in the synthesis of homopolymeric expansion proteins, is becoming more widely appreciated among microsatellite expansion disorders. Such disorders include amyotrophic lateral sclerosis and frontotemporal dementia caused by a hexanucleotide repeat expansion in the C9ORF72 gene (c9FTD/ALS). We and others have recently shown that this bidirectionally transcribed repeat is RAN translated, and the "c9RAN proteins" thusly produced form neuronal inclusions throughout the central nervous system of c9FTD/ALS patients. Nonetheless, the potential contribution of c9RAN proteins to disease pathogenesis remains poorly understood. In the present study, we demonstrate that poly(GA) c9RAN proteins are neurotoxic and may be implicated in the neurodegenerative processes of c9FTD/ALS. Specifically, we show that expression of poly(GA) proteins in cultured cells and primary neurons leads to the formation of soluble and insoluble high molecular weight species, as well as inclusions composed of filaments similar to those observed in c9FTD/ALS brain tissues. The expression of poly(GA) proteins is accompanied by caspase-3 activation, impaired neurite outgrowth, inhibition of proteasome activity, and evidence of endoplasmic reticulum (ER) stress. Of importance, ER stress inhibitors, salubrinal and TUDCA, provide protection against poly(GA)-induced toxicity. Taken together, our data provide compelling evidence towards establishing RAN translation as a pathogenic mechanism of c9FTD/ALS, and suggest that targeting the ER using small molecules may be a promising therapeutic approach for these devastating diseases.
Collapse
Affiliation(s)
- Yong-Jie Zhang
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Karen Jansen-West
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Ya-Fei Xu
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Tania F. Gendron
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Kevin F. Bieniek
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
- Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, MN 55905 USA
| | - Wen-Lang Lin
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Hiroki Sasaguri
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Thomas Caulfield
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Jaime Hubbard
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Lillian Daughrity
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Jeannie Chew
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
- Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, MN 55905 USA
| | | | - Mercedes Prudencio
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | | | | | - Ena Whitelaw
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Peter E. A. Ash
- Department of Pharmacology, Boston University School of Medicine, Boston, MA 02118 USA
| | - Michael DeTure
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Rosa Rademakers
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Kevin B. Boylan
- Department of Neurology, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Dennis W. Dickson
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| | - Leonard Petrucelli
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224 USA
| |
Collapse
|