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Dou D, Aiken J, Holzbaur EL. RAB3 phosphorylation by pathogenic LRRK2 impairs trafficking of synaptic vesicle precursors. J Cell Biol 2024; 223:e202307092. [PMID: 38512027 PMCID: PMC10959120 DOI: 10.1083/jcb.202307092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 02/01/2024] [Accepted: 03/04/2024] [Indexed: 03/22/2024] Open
Abstract
Gain-of-function mutations in the LRRK2 gene cause Parkinson's disease (PD), characterized by debilitating motor and non-motor symptoms. Increased phosphorylation of a subset of RAB GTPases by LRRK2 is implicated in PD pathogenesis. We find that increased phosphorylation of RAB3A, a cardinal synaptic vesicle precursor (SVP) protein, disrupts anterograde axonal transport of SVPs in iPSC-derived human neurons (iNeurons) expressing hyperactive LRRK2-p.R1441H. Knockout of the opposing protein phosphatase 1H (PPM1H) in iNeurons phenocopies this effect. In these models, the compartmental distribution of synaptic proteins is altered; synaptophysin and synaptobrevin-2 become sequestered in the neuronal soma with decreased delivery to presynaptic sites along the axon. We find that RAB3A phosphorylation disrupts binding to the motor adaptor MADD, potentially preventing the formation of the RAB3A-MADD-KIF1A/1Bβ complex driving anterograde SVP transport. RAB3A hyperphosphorylation also disrupts interactions with RAB3GAP and RAB-GDI1. Our results reveal a mechanism by which pathogenic hyperactive LRRK2 may contribute to the altered synaptic homeostasis associated with characteristic non-motor and cognitive manifestations of PD.
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Affiliation(s)
- Dan Dou
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD, USA
- Neuroscience Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jayne Aiken
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Erika L.F. Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD, USA
- Neuroscience Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Mamais A, Sanyal A, Fajfer A, Zykoski CG, Guldin M, Riley-DiPaolo A, Subrahmanian N, Gibbs W, Lin S, LaVoie MJ. The LRRK2 kinase substrates RAB8a and RAB10 contribute complementary but distinct disease-relevant phenotypes in human neurons. Stem Cell Reports 2024; 19:163-173. [PMID: 38307024 PMCID: PMC10874859 DOI: 10.1016/j.stemcr.2024.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 12/31/2023] [Accepted: 01/02/2024] [Indexed: 02/04/2024] Open
Abstract
Mutations in the LRRK2 gene cause familial Parkinson's disease presenting with pleomorphic neuropathology that can involve α-synuclein or tau accumulation. LRRK2 mutations are thought to converge upon a pathogenic increase in LRRK2 kinase activity. A subset of small RAB GTPases has been identified as LRRK2 substrates, with LRRK2-dependent phosphorylation resulting in RAB inactivation. We used CRISPR-Cas9 genome editing to generate a novel series of isogenic iPSC lines deficient in the two most well-validated LRRK2 substrates, RAB8a and RAB10, from deeply phenotyped healthy control lines. Thorough characterization of NGN2-induced neurons revealed opposing effects of RAB8a and RAB10 deficiency on lysosomal pH and Golgi organization, with isolated effects of RAB8a and RAB10 ablation on α-synuclein and tau, respectively. Our data demonstrate largely antagonistic effects of genetic RAB8a or RAB10 inactivation, which provide discrete insight into the pathologic features of their biochemical inactivation by pathogenic LRRK2 mutation in human disease.
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Affiliation(s)
- Adamantios Mamais
- Center for Translational Research in Neurodegenerative Disease and Fixel Institute for Neurologic Diseases, Department of Neurology, University of Florida, Gainesville, FL, USA
| | - Anwesha Sanyal
- Department of Cell Biology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Austin Fajfer
- Center for Translational Research in Neurodegenerative Disease and Fixel Institute for Neurologic Diseases, Department of Neurology, University of Florida, Gainesville, FL, USA
| | - Catherine G Zykoski
- Center for Translational Research in Neurodegenerative Disease and Fixel Institute for Neurologic Diseases, Department of Neurology, University of Florida, Gainesville, FL, USA
| | - Michael Guldin
- Center for Translational Research in Neurodegenerative Disease and Fixel Institute for Neurologic Diseases, Department of Neurology, University of Florida, Gainesville, FL, USA
| | | | - Nitya Subrahmanian
- Center for Translational Research in Neurodegenerative Disease and Fixel Institute for Neurologic Diseases, Department of Neurology, University of Florida, Gainesville, FL, USA
| | - Whitney Gibbs
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Steven Lin
- Ann Romney Center for Neurological Diseases, Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Matthew J LaVoie
- Center for Translational Research in Neurodegenerative Disease and Fixel Institute for Neurologic Diseases, Department of Neurology, University of Florida, Gainesville, FL, USA; Department of Cell Biology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.
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