Inhibition of LRRK2 kinase activity promotes anterograde axonal transport and presynaptic targeting of α-synuclein

Abstract

Pathologic inclusions composed of alpha-synuclein called Lewy pathology are hallmarks of Parkinson Disease (PD). Dominant inherited mutations in leucine rich repeat kinase 2 (LRRK2) are the most common genetic cause of PD. Lewy pathology is found in the majority of individuals with LRRK2-PD, particularly those with the G2019S-LRRK2 mutation. Lewy pathology in LRRK2-PD associates with increased non-motor symptoms such as cognitive deficits, anxiety, and orthostatic hypotension. Thus, understanding the relationship between LRRK2 and alpha-synuclein could be important for determining the mechanisms of non-motor symptoms. In PD models, expression of mutant LRRK2 reduces membrane localization of alpha-synuclein, and enhances formation of pathologic alpha-synuclein, particularly when synaptic activity is increased. alpha-Synuclein and LRRK2 both localize to the presynaptic terminal. LRRK2 plays a role in membrane traffic, including axonal transport, and therefore may influence alpha-synuclein synaptic localization. This study shows that LRRK2 kinase activity influences alpha-synuclein targeting to the presynaptic terminal. We used the selective LRRK2 kinase inhibitors, MLi-2 and PF-06685360 (PF-360) to determine the impact of reduced LRRK2 kinase activity on presynaptic localization of alpha-synuclein. Expansion microscopy (ExM) in primary hippocampal cultures and the mouse striatum, in vivo, was used to more precisely resolve the presynaptic localization of alpha-synuclein. Live imaging of axonal transport of alpha-synuclein-GFP was used to investigate the impact of LRRK2 kinase inhibition on alpha-synuclein axonal transport towards the presynaptic terminal. Reduced LRRK2 kinase activity increases alpha-synuclein overlap with presynaptic markers in primary neurons, and increases anterograde axonal transport of alpha-synuclein-GFP. In vivo, LRRK2 inhibition increases alpha-synuclein overlap with glutamatergic, cortico-striatal terminals, and dopaminergic nigral-striatal presynaptic terminals. The findings suggest that LRRK2 kinase activity plays a role in axonal transport, and presynaptic targeting of alpha-synuclein. These data provide potential mechanisms by which LRRK2-mediated perturbations of alpha-synuclein localization could cause pathology in both LRRK2-PD, and idiopathic PD.

Neuronopathic GBA1 L444P mutation accelerates Glucosylsphingosine levels and formation of hippocampal alpha-synuclein inclusions

“…To study the effects of GBA1 L444P expression on α-syn inclusion formation, we first used primary hippocampal neurons from GBA1 +/+ mice and GBA1 +/L444P knock-in mice exposed to sonicated α-syn fibrils on DIV7 and analyzed 14 days later (DIV21) (Volpicelli-Daley et al, 2011). Primary hippocampal neurons from mice were chosen as our model culture system because we achieve reliable, robust formation of α-syn inclusions in response to exposure to fibrils (Volpicelli-Daley et al, 2014; Froula et al, 2018; Brzozowski et al, 2021; Stoyka et al, 2021). Because the formation of α-syn inclusions depend on neuronal outgrowth (Murphy et al, 2000), we quantified axonal density using neurofilament-H (NFH; heavy polypeptide).…”

LRRK2 Suppresses Lysosome Degradative Activity in Macrophages and Microglia Through MiT-TFE Transcription Factor Inhibition

“…Given the major impact of Parkinson's disease on midbrain dopaminergic neurons, significant attention has focused on neuronal roles for LRRK2 [30][31][32][33] . However, LRRK2 is expressed in diverse non-neuronal cell types.…”