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Larbalestier H, Keatinge M, Watson L, White E, Gowda S, Wei W, Koler K, Semenova SA, Elkin AM, Rimmer N, Sweeney ST, Mazzolini J, Sieger D, Hide W, McDearmid J, Panula P, MacDonald RB, Bandmann O. GCH1 Deficiency Activates Brain Innate Immune Response and Impairs Tyrosine Hydroxylase Homeostasis. J Neurosci 2022; 42:702-716. [PMID: 34876467 PMCID: PMC8805627 DOI: 10.1523/jneurosci.0653-21.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 10/08/2021] [Accepted: 11/03/2021] [Indexed: 11/21/2022] Open
Abstract
The Parkinson's disease (PD) risk gene GTP cyclohydrolase 1 (GCH1) catalyzes the rate-limiting step in tetrahydrobiopterin (BH4) synthesis, an essential cofactor in the synthesis of monoaminergic neurotransmitters. To investigate the mechanisms by which GCH1 deficiency may contribute to PD, we generated a loss of function zebrafish gch1 mutant (gch1-/-), using CRISPR/Cas technology. gch1-/- zebrafish develop marked monoaminergic neurotransmitter deficiencies by 5 d postfertilization (dpf), movement deficits by 8 dpf and lethality by 12 dpf. Tyrosine hydroxylase (Th) protein levels were markedly reduced without loss of ascending dopaminergic (DAergic) neurons. L-DOPA treatment of gch1-/- larvae improved survival without ameliorating the motor phenotype. RNAseq of gch1-/- larval brain tissue identified highly upregulated transcripts involved in innate immune response. Subsequent experiments provided morphologic and functional evidence of microglial activation in gch1-/- The results of our study suggest that GCH1 deficiency may unmask early, subclinical parkinsonism and only indirectly contribute to neuronal cell death via immune-mediated mechanisms. Our work highlights the importance of functional validation for genome-wide association studies (GWAS) risk factors and further emphasizes the important role of inflammation in the pathogenesis of PD.SIGNIFICANCE STATEMENT Genome-wide association studies have now identified at least 90 genetic risk factors for sporadic Parkinson's disease (PD). Zebrafish are an ideal tool to determine the mechanistic role of genome-wide association studies (GWAS) risk genes in a vertebrate animal model. The discovery of GTP cyclohydrolase 1 (GCH1) as a genetic risk factor for PD was counterintuitive, GCH1 is the rate-limiting enzyme in the synthesis of dopamine (DA), mutations had previously been described in the non-neurodegenerative movement disorder dopa-responsive dystonia (DRD). Rather than causing DAergic cell death (as previously hypothesized by others), we now demonstrate that GCH1 impairs tyrosine hydroxylase (Th) homeostasis and activates innate immune mechanisms in the brain and provide evidence of microglial activation and phagocytic activity.
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Affiliation(s)
- Hannah Larbalestier
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Marcus Keatinge
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
- Centre for Discovery Brain Sciences, Chancellor's Building, The University of Edinburgh, Edinburgh EH16 4SB, United Kingdom
| | - Lisa Watson
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Emma White
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Siri Gowda
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Wenbin Wei
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
| | - Katjusa Koler
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
| | - Svetlana A Semenova
- Department of Anatomy, University of Helsinki, Helsinki, Finland, 00014
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland 20892
| | - Adam M Elkin
- Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Neal Rimmer
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Sean T Sweeney
- Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Julie Mazzolini
- Centre for Discovery Brain Sciences, Chancellor's Building, The University of Edinburgh, Edinburgh EH16 4SB, United Kingdom
| | - Dirk Sieger
- Centre for Discovery Brain Sciences, Chancellor's Building, The University of Edinburgh, Edinburgh EH16 4SB, United Kingdom
| | - Winston Hide
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Department of Pathology, Beth Israel Medical Center, Boston, Massachusetts 02215
- Harvard Medical School, Boston, Massachusetts 02115
| | - Jonathan McDearmid
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Pertti Panula
- Department of Anatomy, University of Helsinki, Helsinki, Finland, 00014
| | - Ryan B MacDonald
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Oliver Bandmann
- Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield S10 2HQ, United Kingdom
- Bateson Centre, Firth Court, University of Sheffield, Sheffield S10 2TN, United Kingdom
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