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Krug L, Chatterjee N, Borges-Monroy R, Hearn S, Liao WW, Morrill K, Prazak L, Rozhkov N, Theodorou D, Hammell M, Dubnau J. Retrotransposon activation contributes to neurodegeneration in a Drosophila TDP-43 model of ALS. PLoS Genet 2017; 13:e1006635. [PMID: 28301478 PMCID: PMC5354250 DOI: 10.1371/journal.pgen.1006635] [Citation(s) in RCA: 128] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 02/14/2017] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are two incurable neurodegenerative disorders that exist on a symptomological spectrum and share both genetic underpinnings and pathophysiological hallmarks. Functional abnormality of TAR DNA-binding protein 43 (TDP-43), an aggregation-prone RNA and DNA binding protein, is observed in the vast majority of both familial and sporadic ALS cases and in ~40% of FTLD cases, but the cascade of events leading to cell death are not understood. We have expressed human TDP-43 (hTDP-43) in Drosophila neurons and glia, a model that recapitulates many of the characteristics of TDP-43-linked human disease including protein aggregation pathology, locomotor impairment, and premature death. We report that such expression of hTDP-43 impairs small interfering RNA (siRNA) silencing, which is the major post-transcriptional mechanism of retrotransposable element (RTE) control in somatic tissue. This is accompanied by de-repression of a panel of both LINE and LTR families of RTEs, with somewhat different elements being active in response to hTDP-43 expression in glia versus neurons. hTDP-43 expression in glia causes an early and severe loss of control of a specific RTE, the endogenous retrovirus (ERV) gypsy. We demonstrate that gypsy causes the degenerative phenotypes in these flies because we are able to rescue the toxicity of glial hTDP-43 either by genetically blocking expression of this RTE or by pharmacologically inhibiting RTE reverse transcriptase activity. Moreover, we provide evidence that activation of DNA damage-mediated programmed cell death underlies both neuronal and glial hTDP-43 toxicity, consistent with RTE-mediated effects in both cell types. Our findings suggest a novel mechanism in which RTE activity contributes to neurodegeneration in TDP-43-mediated diseases such as ALS and FTLD.
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Affiliation(s)
- Lisa Krug
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Nabanita Chatterjee
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | | | - Stephen Hearn
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Wen-Wei Liao
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Kathleen Morrill
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Lisa Prazak
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
- Department of Biology, Farmingdale State College, Farmingdale, NY United States of America
| | - Nikolay Rozhkov
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Delphine Theodorou
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Molly Hammell
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Josh Dubnau
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
- Department of Anesthesiology, Stony Brook School of Medicine, Stony Brook, New York, United States of America
- Department of Neurobiology and Behavior, Stony Brook School of Medicine, Stony Brook, New York, United States of America
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