Olympia Apokotou

High consumption of colorful fruits and vegetables correlates with low dementia risk, but the exact molecules and the underlying biological mechanisms governing their bioactive profiles are largely unknown. Using a 10-year observational cohort study coupled with an AI-driven systems pharmacology platform, we identified a natural triterpenoid compound found in colorful fruits and vegetables, α-Amyrin (αA), as a therapeutic candidate for Alzheimer's disease (AD). The efficacy of αA in treating the symptoms of AD, such as Tau tangles, damaged mitochondria, and memory loss, was examined using cross-species models; αA retained memory in AD-like animal models while also strongly inhibiting Tau pathology, especially p-Tau217, in a cellular 'Tau seeding' system and in Tau[P301S] mice, followed by validation using a human 3D microfluidic system. At molecular level, αA is a robust mitochondrial regulator, enhancing mitochondrial stress resilience and activation of mitophagy. Mechanistically, αA inhibits dual leucine zipper kinase (DLK), leading to the inhibition of DLK-Sterile Alpha and TIR Motif Containing 1 (SARM1)-dependent neurodegeneration; this inhibition frees unc-51 Like Autophagy Activating Kinase 1 (ULK1) from the ULK1-SARM1 complex, allowing it to participate in autophagy/mitophagy. αA also shows strong translational potential with a 10.1 h half-life and the ability to cross the blood-brain barrier. Our results indicate that αA may act as a mitochondrial guardian against AD via modulating the DLK-SARM1-ULK1-autophagy/mitophagy axis while further preclinical and clinical studies are warranted.

Abstract Alpha-Synuclein (αSyn) plays a central role in Parkinson’s disease (PD) and the p.A53T mutation causes an early-onset familial form of PD with severe manifestations. The pathological effects of the p.A53T-αSyn mutation have been extensively investigated in neurons, yet the consequences on astrocytes and astrocytic contribution to PD pathology are understudied. Here, we differentiated induced pluripotent stem cells from PD patients carrying the p.A53T-αSyn mutation to astrocytes, which uncovered cell-intrinsic phenotypes, including calcium dyshomeostasis and accumulation of protein aggregates. Proteomic profiling and functional analyses revealed perturbed protein catabolic processes, involving the proteasome and autophagy, associated with lysosomal malfunction. Dopamine neurons co-cultured with p.A53T-αSyn astrocytes displayed exacerbated neurodegeneration with hallmark Lewy-like pathologies, reversed by control astrocytes at least due to their ability to resolve neuronal αSyn aggregates by endocytic clearance. Our findings underscore a critical impact of p.A53T-αSyn on astrocytic protein quality control mechanisms, positioning astrocytes as important contributors to PD neuropathology. Highlights iPSC-derived astrocytes from PD patients with the p.A53T-αSyn mutation display cell-autonomous pathological phenotypes and toxic αSyn accumulation Proteome and functional analyses reveal failure of major proteostasis mechanisms in p.A53T-αSyn astrocytes, largely related to lysosomal malfunction Inherent Lewy-like pathological features are identified in p.A53T-αSyn astrocyte-neuron co-cultures p.A53T-αSyn astrocytes induce PD-relevant neuropathology to healthy neurons Control but not p.A53T-αSyn astrocytes alleviate neuropathology in co-cultured neurons

Alpha-Synuclein (αSyn) plays a central role in Parkinson's disease (PD), and the p.A53T mutation causes an early-onset familial form of PD with severe manifestations. While its effects on neurons are well studied, its consequences on astrocytes and astrocytic contribution to PD pathology are understudied. Here, we differentiated patient-derived p.A53T-αSyn induced pluripotent stem cells (iPSC) to ventral midbrain astrocytes and characterized them via comprehensive molecular, functional, and proteomic analyses. Gene-corrected and healthy iPSC-derived astrocytes served as controls. To assess the effects of p.A53T-αSyn astrocytes on dopamine neurons, we established neuron-astrocyte cocultures of iPSC-derived control and mutant cells at all combinations. Our analyses uncovered cell-intrinsic pathologies in p.A53T-αSyn astrocytes, such as calcium dyshomeostasis, and accumulation of protein aggregates including those of phosphorylated αSyn. Proteomic and mechanistic studies demonstrated perturbed protein catabolic processes, with associated disturbances in lysosomal function and mTOR signaling. These deficits reduced the endocytic clearance capacity of p.A53T-αSyn astrocytes and their ability to process exogenous αSyn cargo. p.A53T-αSyn dopamine neurons cocultured with p.A53T-αSyn astrocytes displayed Lewy-like pathologies, mirroring the histopathological hallmarks identified in postmortem PD brains and exacerbated neurodegeneration, in anatomical and functional aspects. Control astrocytes mitigated these pathologies, highlighting their neuroprotective role. Additionally, p.A53T-αSyn astrocytes induced PD-relevant pathology ιn control neurons. Our findings, validated using an isogenic pair, demonstrate a critical impact of p.A53T-αSyn in disrupting astrocytic protein quality control mechanisms and establish astrocytes as active contributors to PD neuropathology. Our two-dimensional coculture model reflects key aspects of PD pathology, offering a relevant platform for mechanistic and drug discovery studies.