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Kinase inhibition of G2019S-LRRK2 enhances autolysosome formation and function to reduce endogenous alpha-synuclein intracellular inclusions.

ABSTRACT: The Parkinson's disease (PD)-associated kinase Leucine-Rich Repeat Kinase 2 (LRRK2) is a crucial modulator of the autophagy-lysosome pathway, but unclarity exists on the precise mechanics of its role and the direction of this modulation. In particular, LRRK2 is involved in the degradation of pathological alpha-synuclein, with pathogenic mutations precipitating neuropathology in cellular and animal models of PD, and a significant proportion of LRRK2 patients presenting Lewy neuropathology. Defects in autophagic processing and lysosomal degradation of alpha-synuclein have been postulated to underlie its accumulation and onset of neuropathology. Thus, it is critical to obtain a comprehensive knowledge on LRRK2-associated pathology. Here, we investigated a G2019S-LRRK2 recombinant cell line exhibiting accumulation of endogenous, phosphorylated alpha-synuclein. We found that G2019S-LRRK2 leads to accumulation of LC3 and abnormalities in lysosome morphology and proteolytic activity in a kinase-dependent fashion, but independent from constitutively active Rab10. Notably, LRRK2 inhibition was ineffective upon upstream blockade of autophagosome-lysosome fusion events, highlighting this step as critical for alpha-synuclein clearance.

SUBMITTER: Obergasteiger J

PROVIDER: S-EPMC7280235 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Kinase inhibition of G2019S-LRRK2 enhances autolysosome formation and function to reduce endogenous alpha-synuclein intracellular inclusions.

Obergasteiger Julia J Frapporti Giulia G Lamonaca Giulia G Pizzi Sara S Picard Anne A Lavdas Alexandros A AA Pischedda Francesca F Piccoli Giovanni G Hilfiker Sabine S Lobbestael Evy E Baekelandt Veerle V Hicks Andrew A AA Corti Corrado C Pramstaller Peter P PP Volta Mattia M

Cell death discovery 20200608

The Parkinson's disease (PD)-associated kinase Leucine-Rich Repeat Kinase 2 (LRRK2) is a crucial modulator of the autophagy-lysosome pathway, but unclarity exists on the precise mechanics of its role and the direction of this modulation. In particular, LRRK2 is involved in the degradation of pathological alpha-synuclein, with pathogenic mutations precipitating neuropathology in cellular and animal models of PD, and a significant proportion of LRRK2 patients presenting Lewy neuropathology. Defect ...[more]

PMID: 32550012

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Project description:Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common genetic cause of Parkinson's disease. Here, we investigated whether the G2019S LRRK2 mutation causes morphological and/or functional changes at nigro-striatal dopamine neurons. Density of striatal dopaminergic terminals, nigral cell counts, tyrosine hydroxylase protein levels as well as exocytotic dopamine release measured in striatal synaptosomes, or striatal extracellular dopamine levels monitored by in vivo microdialysis were similar between ≥12-month-old G2019S knock-in mice and wild-type controls. In vivo striatal dopamine release was insensitive to the LRRK2 inhibitor Nov-LRRK2-11, and was elevated by the membrane dopamine transporter blocker GBR-12783. However, G2019S knock-in mice showed a blunted neurochemical and motor activation response to GBR-12783 compared to wild-type controls. Western blot and dopamine uptake analysis revealed an increase in dopamine transporter levels and activity in the striatum of 12-month-old G2019S KI mice. This phenotype correlated with a reduction in vesicular monoamine transporter 2 levels and an enhancement of vesicular dopamine uptake, which was consistent with greater resistance to reserpine-induced hypolocomotion. These changes were not observed in 3-month-old mice. Finally, Western blot analysis revealed no genotype difference in striatal levels of endogenous α-synuclein or α-synuclein bound to DOPAL (a toxic metabolite of dopamine). However, Serine129-phosphorylated α-synuclein levels were higher in 12-month-old G2019S knock-in mice. Immunohistochemistry confirmed this finding, also showing no genotype difference in 3-month-old mice. We conclude that the G2019S mutation causes progressive dysfunctions of dopamine transporters, along with Serine129-phosphorylated α-synuclein overload, at striatal dopaminergic terminals, which are not associated with dopamine homeostasis dysregulation or neuron loss but might contribute to intrinsic dopaminergic terminal vulnerability. We propose G2019S knock-in mice as a presymptomatic Parkinson's disease model, useful to investigate the pathogenic interaction among genetics, aging, and internal or environmental factors leading to the disease.

Project description:Leucine-rich repeat kinase 2 (LRRK2) and α-synuclein share enigmatic roles in the pathobiology of Parkinson's disease (PD). LRRK2 mutations are a common genetic cause of PD which, in addition to neurodegeneration, often present with abnormal deposits of α-synuclein in the form of Lewy-related pathology. As Lewy-related pathology is a prominent neuropathologic finding in sporadic PD, the relationship between LRRK2 and α-synuclein has garnered considerable interest. However, whether and how LRRK2 might influence the accumulation of Lewy-related pathology remains poorly understood. Through stereotactic injection of mouse α-synuclein pre-formed fibrils (PFF), we modeled the spread of Lewy-related pathology within forebrain regions where LRRK2 is most highly expressed. The impact of LRRK2 genotype on the formation of α-synuclein inclusions was evaluated at 1-month post-injection. Neither deletion of LRRK2 nor G2019S LRRK2 knockin appreciably altered the burden of α- synuclein pathology at this early timepoint. These observations fail to provide support for a robust pathophysiologic interaction between LRRK2 and α-synuclein in the forebrain in vivo . There was, however, a modest reduction in microglial activation induced by PFF delivery in the hippocampus of LRRK2 knockout mice, suggesting that LRRK2 may contribute to α-synuclein-induced neuroinflammation. Collectively, our data indicate that the pathological accumulation of α-synuclein in the mouse forebrain is largely independent of LRRK2.HighlightsAdult mice accumulate α-synuclein pathology in the hippocampus and cortex following stereotactic injection with α-synuclein PFFs, with negligible influence of LRRK2 genotype. Hippocampal and cortical α-synuclein pathology elicits the concomitant accrual of phosphorylated tau, reactive astrogliosis, and microglial activation. Absence of endogenous LRRK2 attenuates microglial activation in the dorsal hippocampus induced by PFFs, but not in the entorhinal cortex. Accumulation of α-synuclein inclusions and related neuropathologic changes were strongly associated across the hippocampal dorsal-ventral axis, regardless of LRRK2 genotype.

Dataset Information

Kinase inhibition of G2019S-LRRK2 enhances autolysosome formation and function to reduce endogenous alpha-synuclein intracellular inclusions.

Publications

Kinase inhibition of G2019S-LRRK2 enhances autolysosome formation and function to reduce endogenous alpha-synuclein intracellular inclusions.

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