PF-06447475 Molecule Attenuates the Neuropathology of Familial Alzheimer's and Coexistent Parkinson's Disease Markers in PSEN1 I416T Dopaminergic-like Neurons.

Abstract

Familial Alzheimer's disease (FAD) is a complex multifactorial disorder clinically characterized by cognitive impairment and memory loss. Pathologically, FAD is characterized by intracellular accumulation of the protein fragment Aβ42 (iAβ), hyperphosphorylated microtubule-associated protein TAU (p-TAU), and extensive degeneration of basal forebrain cholinergic neurons of the nucleus basalis of Meynert (NbM) and the medial septal nucleus (MSN), mainly caused by mutations in the amyloid precursor protein (APP), presenilin 1 (PSEN1), and PSEN2 gene. Since the dopaminergic system may contribute to FAD symptoms, alterations in the nigro-hippocampal pathway may be associated with cognitive impairment in FAD. Interestingly, p-α-synuclein (p-α-Syn), Aβ, and p-TAU have been found to coexist in vulnerable regions of postmortem AD brains. However, the mechanism by which Aβ, p-TAU, and α-Syn coexist in DAergic neurons in AD brains has not been determined. We generated PSEN1 I416T dopaminergic-like neurons (DALNs) from I416T menstrual stromal cells (MenSCs) in NeuroForsk 2.0 medium for 7 days and then cultured them in minimal culture medium (MCm) for another 4 days. On day 11, DALNs were analyzed for molecular and pathological markers by flow cytometry and fluorescence microscopy. We found that mutant DALNs showed increased accumulation of iAβ as well as increased phosphorylation of TAU at S202/T205 compared to WT DALNs. Thus, mutant DALNs exhibited typical pathological hallmarks of Alzheimer's disease. Furthermore, PSEN1 I416T DALNs showed concomitant signs of OS as evidenced by the appearance of oxidized sensor protein DJ-1 (i.e., DJ-1C106-SO₃) and apoptotic markers TP53, pS63-c-JUN, PUMA, and cleavage caspase 3 (CC3). Notably, these DALNs exhibited PD-associated proteins such as intracellular accumulation of α-Syn (detected as aggregates of pS129-α-Syn) and phosphorylation of LRRK2 kinase at residue S935. In addition, mutant DALNs showed a 17.16- and 6.17-fold decrease in DA-induced Ca²⁺ flux, compared to WT DALNs. These observations suggest that iAβ and p-TAU, together with p-α-Syn, and p-LRRK2 kinase, may damage DAergic neurons and thereby contribute to the exacerbation of neuropathologic processes in FAD. Remarkably, the LRRK2 inhibitor PF-06447475 (PF-475) significantly reversed PSEN1 I416T-induced neuropathological markers in DAergic neurons. PF-465 inhibitor reduced iAβ, oxDJ-1C106-SO₃, and p-TAU. In addition, this inhibitor reduced pS935-LRRK2, pS129-αSYN, pS63-c-JUN, and CC3. We conclude that the observed neuroprotective effects of PF-475 are due to direct inhibition of LRRK2 activity and that the LRRK2 protein is upstream of the molecular cascade of apoptosis and proteinopathy. Our results suggest that PF-475 is an effective neuroprotective agent against endogenous PSEN1 I416T-induced neurotoxicity in DALNs coexisting with Parkinson's disease markers. Therefore, PF-475 may be of great therapeutic value in FAD.