Mitochondrial Dynamics-Related Gene Regulation by Epigenetic Suppression of GCN5 Exerts Neuroprotective Effects in...

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by dopaminergic neuron loss and mitochondrial dysfunction. Recent studies implicate the histone acetyltransferase GCN5 in regulating mitochondrial homeostasis and oxidative stress. This study investigated the therapeutic potential of GCN5 silencing via systemically administered siRNA-loaded niosomes in a rotenone-induced rat model of PD. Niosomes were prepared using the thin-film hydration method, and the most effective siRNA sequence was selected through real time quantitative PCR (RT-qPCR) and immunofluorescence in primary mesencephalic neurons. Adult male rats were divided into four groups (n = 24/group), and PD was induced with rotenone (2 mg/kg/day, s.c., for 35 days). Behavioral assessments, biochemical analyses, IVIS imaging, histopathology, immunohistochemistry, and RT-qPCR were conducted. IVIS confirmed brain accumulation of siRNA-niosomes within 3-5 h post-injection. GCN5 siRNA treatment significantly improved locomotor activity (p < 0.05), decreased MDA levels (p < 0.05), and restored SOD and dopamine levels (p < 0.05). Molecular findings showed decreased GCN5 and mitochondrial fission-related gene Drp-1 expression, increased expression of mitophagy and biogenesis markers (↑Parkin, ↑PINK1, ↑Mfn2, ↑PGC-1α), elevated TH expression, and reduced α-synuclein accumulation. Histological analysis revealed preserved midbrain cytoarchitecture and reduced neuronal damage. In conclusion, these findings highlight that epigenetic silencing of GCN5 via siRNA-loaded niosomal delivery provides neuroprotection in PD by modulating the expression of genes involved in mitochondrial dynamics, offering preclinical support for its development as a novel therapeutic strategy.