Is serine racemase (SRR) a second hit target for LRRK2-G2019S induced Parkinson’s disease?

Background: Inherited mutations in the LRRK2 protein are the common causes of Parkinson’s disease, but the mechanisms by which increased kinase activity of mutant LRRK2 leads to pathological events remain to be determined. In vitro assays (heterologous cell culture, phospho-protein mass spectrometry) suggest that several Rab proteins might be directly phosphorylated by LRRK2-G2019S. An in vivo screen of Rab expression in dopaminergic neurons in young adult Drosophila demonstrated a strong genetic interaction between LRRK2-G2019S and Rab10. Objective: To determine if Rab10 is necessary for LRRK2-induced pathophysiological responses in the neurons that control movement, vision, circadian activity, and memory. These four systems were chosen because they are modulated by dopaminergic neurons in both humans and flies. Methods: LRRK2-G2019S was expressed in Drosophila dopaminergic neurons and the effects of Rab10 depletion on Proboscis Extension, retinal neurophysiology, circadian activity pattern (‘sleep’), and courtship memory determined in aged flies. Results: Rab10 loss-of-function rescued LRRK2-G2019S induced bradykinesia and retinal signaling deficits. Rab10 knock-down, however, did not rescue the marked sleep phenotype which results from dopaminergic LRRK2-G2019S. Courtship memory is not affected by LRRK2, but is markedly improved by Rab10 depletion. Anatomically, both LRRK2-G2019S and Rab10 are seen in the cytoplasm and at the synaptic endings of dopaminergic neurons. Conclusion: We conclude that, in Drosophila dopaminergic neurons, Rab10 is involved in some, but not all, LRRK2-induced behavioral deficits. Therefore, variations in Rab expression may contribute to susceptibility of different dopaminergic nuclei to neurodegeneration seen in people with Parkinson’s disease.

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LRRK2 G2019S is a common mutation in Spanish patients with late-onset Parkinson's disease

Neuroscience Letters ◽

10.1016/j.neulet.2005.10.083 ◽

2006 ◽

Vol 395 (3) ◽

pp. 224-226 ◽

Cited By ~ 49

Author(s):

Jon Infante ◽

Eloy Rodríguez ◽

Onofre Combarros ◽

Ignacio Mateo ◽

Ana Fontalba ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Late Onset ◽

Common Mutation ◽

Lrrk2 G2019s

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Generation of gene-corrected iPSC line from Parkinson's disease patient iPSC with LRRK2 G2019S mutation using BAC-based homologous recombination

IBRO Reports ◽

10.1016/j.ibror.2019.07.926 ◽

2019 ◽

Vol 6 ◽

pp. S300

Author(s):

Seo-Young Lee ◽

Sangkyun Jeong ◽

Sun-Ku Chung

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Homologous Recombination ◽

Disease Patient ◽

Ipsc Line ◽

G2019s Mutation ◽

Lrrk2 G2019s

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Accurate MS-based Rab10 Phosphorylation Stoichiometry Determination as Readout for LRRK2 Activity in Parkinson's Disease

Molecular & Cellular Proteomics ◽

10.1074/mcp.ra120.002055 ◽

2020 ◽

Vol 19 (9) ◽

pp. 1546-1560 ◽

Cited By ~ 1

Author(s):

Özge Karayel ◽

Francesca Tonelli ◽

Sebastian Virreira Winter ◽

Phillip E. Geyer ◽

Ying Fan ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Drug Target ◽

Patient Stratification ◽

Leucine Rich Repeat ◽

Target Engagement ◽

Mutation Carriers ◽

Lrrk2 G2019s ◽

Before And After ◽

Inhibitor Treatment

Pathogenic mutations in the Leucine-rich repeat kinase 2 (LRRK2) are the predominant genetic cause of Parkinson's disease (PD). They increase its activity, resulting in augmented Rab10-Thr73 phosphorylation and conversely, LRRK2 inhibition decreases pRab10 levels. Currently, there is no assay to quantify pRab10 levels for drug target engagement or patient stratification. To meet this challenge, we developed an high accuracy and sensitivity targeted mass spectrometry (MS)-based assay for determining Rab10-Thr73 phosphorylation stoichiometry in human samples. It uses synthetic stable isotope-labeled (SIL) analogues for both phosphorylated and nonphosphorylated tryptic peptides surrounding Rab10-Thr73 to directly derive the percentage of Rab10 phosphorylation from attomole amounts of the endogenous phosphopeptide. The SIL and the endogenous phosphopeptides are separately admitted into an Orbitrap analyzer with the appropriate injection times. We test the reproducibility of our assay by determining Rab10-Thr73 phosphorylation stoichiometry in neutrophils of LRRK2 mutation carriers before and after LRRK2 inhibition. Compared with healthy controls, the PD predisposing mutation carriers LRRK2 G2019S and VPS35 D620N display 1.9-fold and 3.7-fold increased pRab10 levels, respectively. Our generic MS-based assay further establishes the relevance of pRab10 as a prognostic PD marker and is a powerful tool for determining LRRK2 inhibitor efficacy and for stratifying PD patients for LRRK2 inhibitor treatment.

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