DECODING Β-AMYLOID TOXICITY THROUGH SPATIOTEMPORAL AND INTERACTOMIC PROFILING OF RHO GTPASES

Synaptic dysfunction and dendritic spine loss are early pathological hallmarks of Alzheimer’s disease (AD) and strongly correlate with cognitive decline. Soluble β-amyloid (Aβ) oligomers play a central role in these alterations, yet the molecular signaling mechanisms translating Aβ exposure into synaptic collapse remain incompletely understood. Rho GTPases are key regulators of actin and microtubule dynamics underlying dendritic spine structure and plasticity; however, their regulation during Aβ-mediated toxicity remains controversial.
Here, we investigate the spatiotemporal dynamics of Rho GTPase signaling in hippocampal neurons exposed to Aβ₁–₄₂ oligomers. Primary hippocampal neurons were monitored using genetically encoded FRET biosensors to resolve RhoA, Rac1, and Cdc42 activity with high spatial and temporal resolution. In parallel, we established a TurboID-based proximity labeling strategy to enable future mapping of Aβ-dependent remodeling of Rho GTPase interaction networks.
Preliminary results indicate that acute Aβ₁–₄₂ exposure induces rapid and transient alterations in Rho GTPase activity. Within minutes, RhoA and Rac1 activities are increased, whereas Cdc42 activity is reduced in dendrites, revealing an early and reversible signaling imbalance that normalizes at later time points. We also demonstrate robust expression and enzymatic activity of TurboID–Rho GTPase constructs in hippocampal neurons, supporting the feasibility of temporally resolved interactome studies.
Together, these findings suggest that β-amyloid oligomers rapidly reprogram Rho GTPase activity programs prior to synaptic loss. Future integration of spatiotemporal activity mapping with interactome-based approaches is expected to provide insight into early mechanisms of synaptic vulnerability and identify potential therapeutic targets at preclinical stages of Alzheimer’s disease.