Long-term RNAi knockdown of α-synuclein in the adult rat substantia nigra without neurodegeneration
α-Synuclein plays a central role in the pathogenesis of Parkinson's disease (PD); interventions that decrease its expression appear neuroprotective in PD models. Successful translation of these observations into effective therapies will be dependent on the safety of suppressing α-synuclein expr...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2019-05-01
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| Series: | Neurobiology of Disease |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0969996118305606 |
| _version_ | 1818576172479414272 |
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| author | Alevtina Zharikov Qing Bai Briana R. De Miranda Amber Van Laar J. Timothy Greenamyre Edward A. Burton |
| author_facet | Alevtina Zharikov Qing Bai Briana R. De Miranda Amber Van Laar J. Timothy Greenamyre Edward A. Burton |
| author_sort | Alevtina Zharikov |
| collection | DOAJ |
| description | α-Synuclein plays a central role in the pathogenesis of Parkinson's disease (PD); interventions that decrease its expression appear neuroprotective in PD models. Successful translation of these observations into effective therapies will be dependent on the safety of suppressing α-synuclein expression in the adult brain. We investigated long-term α-synuclein knockdown in the adult rat CNS. 8-month old animals received either AAV-sh[Snca] (an RNA interference vector targeting the Snca mRNA transcript) or AAV-sh[Ctrl] (a control vector) unilaterally into the substantia nigra. No signs of systemic toxicity or motor dysfunction were observed in either experimental group over 12 months. Viral transgene expression persisted to 12 months post-inoculation, at which point Snca mRNA expression in substantia nigra dopaminergic neurons of animals that received AAV-sh[Snca] was decreased by ≈90%, and α-synuclein immunoreactivity by >70% relative to the control side. Stereological quantification of Nissl-labeled neurons showed no evidence of neurodegeneration in the substantia nigra 12 months after inoculation with either vector, and we observed abundant dopaminergic neurons with minimal α-synuclein immunoreactivity that appeared otherwise unremarkable in the AAV-sh[Snca] group. Despite the absence of neurodegeneration, some loss of TH expression was evident in nigral neurons after transduction with either vector, presumably a non-specific consequence of vector delivery, cellular transduction, or expression of shRNA or GFP. We conclude that long-term α-synuclein knockdown in the substantia nigra does not cause significant functional deficits in the ascending dopaminergic projection, or neurodegeneration. These findings are encouraging that it may be feasible to target α-synuclein expression therapeutically in PD. |
| first_indexed | 2024-12-16T06:09:48Z |
| format | Article |
| id | doaj.art-33a0acbb16ac4a8ca24e028ce31621f2 |
| institution | Directory Open Access Journal |
| issn | 1095-953X |
| language | English |
| last_indexed | 2024-12-16T06:09:48Z |
| publishDate | 2019-05-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Neurobiology of Disease |
| spelling | doaj.art-33a0acbb16ac4a8ca24e028ce31621f22022-12-21T22:41:25ZengElsevierNeurobiology of Disease1095-953X2019-05-01125146153Long-term RNAi knockdown of α-synuclein in the adult rat substantia nigra without neurodegenerationAlevtina Zharikov0Qing Bai1Briana R. De Miranda2Amber Van Laar3J. Timothy Greenamyre4Edward A. Burton5Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USADepartment of Neurology, University of Pittsburgh, Pittsburgh, PA, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USADepartment of Neurology, University of Pittsburgh, Pittsburgh, PA, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USADepartment of Neurology, University of Pittsburgh, Pittsburgh, PA, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USADepartment of Neurology, University of Pittsburgh, Pittsburgh, PA, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USA; Geriatric Research, Education and Clinical Center, Pittsburgh VA Healthcare System, Pittsburgh, PA, USADepartment of Neurology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USA; Geriatric Research, Education and Clinical Center, Pittsburgh VA Healthcare System, Pittsburgh, PA, USA; Corresponding author at: 7015 Biomedical Sciences Tower 3, 3501 Fifth Avenue, Pittsburgh, PA 15213, USA.α-Synuclein plays a central role in the pathogenesis of Parkinson's disease (PD); interventions that decrease its expression appear neuroprotective in PD models. Successful translation of these observations into effective therapies will be dependent on the safety of suppressing α-synuclein expression in the adult brain. We investigated long-term α-synuclein knockdown in the adult rat CNS. 8-month old animals received either AAV-sh[Snca] (an RNA interference vector targeting the Snca mRNA transcript) or AAV-sh[Ctrl] (a control vector) unilaterally into the substantia nigra. No signs of systemic toxicity or motor dysfunction were observed in either experimental group over 12 months. Viral transgene expression persisted to 12 months post-inoculation, at which point Snca mRNA expression in substantia nigra dopaminergic neurons of animals that received AAV-sh[Snca] was decreased by ≈90%, and α-synuclein immunoreactivity by >70% relative to the control side. Stereological quantification of Nissl-labeled neurons showed no evidence of neurodegeneration in the substantia nigra 12 months after inoculation with either vector, and we observed abundant dopaminergic neurons with minimal α-synuclein immunoreactivity that appeared otherwise unremarkable in the AAV-sh[Snca] group. Despite the absence of neurodegeneration, some loss of TH expression was evident in nigral neurons after transduction with either vector, presumably a non-specific consequence of vector delivery, cellular transduction, or expression of shRNA or GFP. We conclude that long-term α-synuclein knockdown in the substantia nigra does not cause significant functional deficits in the ascending dopaminergic projection, or neurodegeneration. These findings are encouraging that it may be feasible to target α-synuclein expression therapeutically in PD.http://www.sciencedirect.com/science/article/pii/S0969996118305606 |
| spellingShingle | Alevtina Zharikov Qing Bai Briana R. De Miranda Amber Van Laar J. Timothy Greenamyre Edward A. Burton Long-term RNAi knockdown of α-synuclein in the adult rat substantia nigra without neurodegeneration Neurobiology of Disease |
| title | Long-term RNAi knockdown of α-synuclein in the adult rat substantia nigra without neurodegeneration |
| title_full | Long-term RNAi knockdown of α-synuclein in the adult rat substantia nigra without neurodegeneration |
| title_fullStr | Long-term RNAi knockdown of α-synuclein in the adult rat substantia nigra without neurodegeneration |
| title_full_unstemmed | Long-term RNAi knockdown of α-synuclein in the adult rat substantia nigra without neurodegeneration |
| title_short | Long-term RNAi knockdown of α-synuclein in the adult rat substantia nigra without neurodegeneration |
| title_sort | long term rnai knockdown of α synuclein in the adult rat substantia nigra without neurodegeneration |
| url | http://www.sciencedirect.com/science/article/pii/S0969996118305606 |
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