Neuroprotective Effect of the LRRK2 Kinase Inhibitor PF-06447475 in Human Nerve-Like Differentiated Cells Exposed to Oxidative Stress Stimuli: Implications for Parkinson's Disease

Leucine-rich repeat kinase 2 (LRRK2) has been implicated in oxidative stress (OS) and neurodegeneration in Parkinson's disease (PD). However, the pathophysiological mechanism of the LRRK2 kinase in neurons under stress stimuli is not yet understood. We demonstrate that rotenone (ROT), a mitochondria complex I inhibitor frequently used to generate in vitro and in vivo experimental models of PD, induces LRRK2 phosphorylation at serine 935 p-(S935) concomitant with cell death in nerve-like differentiated cells (NLCs). Indeed, ROT (50 µM) at 6 h exposure significantly increased Reactive Oxygen Species (ROS) (~100 %), p-(S935)-LRRK2 kinase [~2 f(old)-(i)ncrease] level, induced nuclei condensation/fragmentation (16 %), increased the expression of NF-κB (5.6 f-i), p53 (5.3 f-i), c-Jun (5.4 f-i) transcription factors, activated Caspase-3 (8.0 f-i) and AIF (6.8 f-i) proteins; but significantly decreased mitochondrial membrane potential (∆Ψ_m, ~21 %), indicative of Apoptosis -a type of regulated cell death process- compared to untreated cells. Strikingly, the LRRK2 kinase inhibitor PF-06447475 (PF-475, 1 µM) protects NLCs against ROT induced noxious effect. The inhibitor not only blocked the p-(S935)-LRRK2 kinase phosphorylation but also completely abolished ROS, and significantly reversed all ROT-induced Apoptosis signaling and OS associated markers to comparable control values. We conclude that wild-type LRRK2 may act as a pro-apoptotic factor under OS stimuli. Our findings suggest an association between OS and LRRK2 phosphorylation in the NLCs death process, as PD model. Therefore, the pharmacological inhibition of LRRK2 might help to understand the OS-mediated kinase activation in PD neurodegenerative disorder.