The G2019S missense mutation in Leucine-rich repeat kinase (LRRK2) gene is associated with kinase hyperactivity and increased risk of PD. Recently vitamin B12 was reported to allosterically inhibit LRRK2 kinase activity. We aim to investigate whether vitamin B12 dose-dependently inhibits LRRK2 kinase activity in neuronal cells overexpressing wild-type (WT) or G2019S LRRK2.
Human neuroblastoma SHSY-5Y cells were transfected with WT and G2019S LRRK2 using BacMam viral gene delivery system and exposed to vitamin B12 at different concentrations. After 24h their protein was isolated. Levels of p-LRRK2 (S935), LRRK2, Rab10, and p-Rab10 (T73) were analyzed in both the groups. The effects of vitamin B12 on cytotoxicity induced by PD-associated toxins MPP+ and rotenone were also assessed using MTS assay.
p-LRRK2 (S935)/LRRK2 and p-Rab10 (T73)/Rab10 ratios were significantly lower in G2019S LRRK2-overexpressing cells treated with B12, compared to untreated controls. In WT LRRK2-overexpressing cells however, no significant effect of B12 was observed. Vitamin B12 also significantly reduced MPP+ and rotenone toxicity in SHSY-5Y cells.
Vitamin B12 significantly reduced markers of LRRK2 kinase activity in G2019S LRRK2-overexpressing SHSY-5Y cells. Additionally, B12 improved cell viability of oxidative toxin-exposed cells, supporting its neuroprotective potential. These preliminary findings encourage further evaluation of vitamin B12 in disease-modifying therapy for LRRK2 PD.