Dual Inhibitors Targeting G9a and GSK-3β: Translational Perspectives on Alzheimer’s Disease Treatment

Abstract Epigenetic dysregulation and abnormal kinase signaling are key factors in Alzheimer’s disease (AD), yet no existing treatment targets both. We introduce a dual-targeting strategy that inhibits the histone methyltransferase G9a and the serine/threonine kinase GSK-3β—two synergistic drivers of neurodegeneration—using a single CNS-penetrant small molecule. This report covers the rational design, synthesis, and preclinical testing of T2 as a new therapeutic candidate. Structure-based pharmacophore modeling and medicinal chemistry refinement led to a focused library of dual inhibitors, with T2 standing out due to its balanced potency against both targets, ability to cross the blood-brain barrier, low off-target effects, and a favorable safety profile. In the SAMP8 mouse model of late-onset AD, T2 markedly improved memory, restored social behaviors, and increased synaptic complexity. Molecular studies showed that T2 treatment lowered tau phosphorylation, the Aβ42/40 ratio, and neurofilament light chain levels, while boosting neurotrophic factors and anti-inflammatory pathways. Multi-omics analyses indicated that T2 causes widespread transcriptional and proteomic changes, activating synaptic plasticity genes (like Arc and Nectin3 ), reducing ferroptosis and senescence-related pathways, and altering chromatin accessibility. Electrophysiological tests confirmed the restoration of AMPAR-mediated synaptic transmission. Overall, these results support dual G9a/GSK-3β inhibition as a promising disease-modifying approach for AD, with T2 emerging as a strong candidate for further therapeutic development.