The Human LRRK2-R1441G Mutation Drives Age-Dependent Oxidative Stress and Mitochondrial Dysfunction in Dopaminergic...

Mitochondrial dysfunction and oxidative stress are central to the pathogenesis of Parkinson's disease (PD), particularly affecting substantia nigra pars compacta (SNc) dopamine (DA) neurons. Here, we investigate how the R1441G mutation in leucine-rich repeat kinase 2 (LRRK2), a key genetic contributor to familial and sporadic PD, impacts mitochondrial function in midbrain DA neurons.

We employed a BAC transgenic mouse model overexpressing human LRRK2-R1441G and crossed it with TH-mito-roGFP mice to enable mitochondria-targeted redox imaging specifically in DA neurons. Acute midbrain slices from 3-, 6-, and 10-month-old mice were imaged using two-photon microscopy to assess mitochondrial oxidative stress. In parallel, mitochondrial respiratory function, membrane potential flickering events, and expression of uncoupling proteins (UCP4/UCP5) were analyzed. Spatial transcriptomic profiling was performed using the GeoMx^® Digital Spatial Profiler to uncover associated molecular alterations.

We observed a progressive increase in mitochondrial oxidative stress in SNc DA neurons of LRRK2 BAC-hR1441G mice at 3, 6, and 10 months of age. This was accompanied by reduced respiratory complex activity, attenuated mitochondrial membrane potential flickering, and diminished expression of UCP4 and UCP5. Spatial transcriptomic analysis revealed dysregulation of genes linked to mitochondrial uncoupling, calcium signaling, and redox regulation in LRRK2-R1441G SNc tissue.

These findings reveal an age-dependent progression of mitochondrial dysfunction in LRRK2-R1441G SNc DA neurons. Dysregulation of calcium channels and uncoupling proteins emerges as a key mechanism contributing to bioenergetic failure, suggesting potential therapeutic targets to mitigate PD progression.