Curcumin slows the progression of Alzheimer's disease by modulating mitochondrial stress responses via JMJD3-H3K27me3-BDNF axis.

Disturbance of mitochondrial proteins by amyloid beta-protein (Aβ) that associates with mitochondrial stress responses (MSR) is one of the pathological mechanisms of Alzheimer's disease (AD). This study tried to explore whether the axis of Jumonji domain-containing protein 3 (JMJD3)-trimethylated lysine 27 on histone H3 (H3K27me3)-brain derived neurotrophic factor (BDNF) is involved in the regulation of MSR which in turn intervenes in the process of AD, and whether curcumin (CUR) has a protective role against AD by influencing this axis, aiming to provide insights into AD treatment. AD mouse models presented a significant aggregation of Aβ, with conspicuous pathological changes in brain tissues and an increase in neuronal apoptosis. Moreover, the mRNA and protein levels of JMJD3 and BDNF were down-regulated, H3K27me3 methylation levels were increased, and the MSR markers (ClpP, HSP6, HSP-60, and ATFS-1) showed abnormal alterations. In cellular models of AD, up-regulation of either JMJD3 or BDNF up-regulated BDNF levels, down-regulated H3K27me3 methylation levels, mitigated abnormalities of MSR markers and Aβ aggregation, and increased cell proliferation and inhibited apoptosis. JMJD3 was confirmed to regulate Aβ and MSR via BDNF. In addition, CUR was confirmed to modulate JMJD3-H3K27me3-BDNF axis. Furthermore, moderate and high doses of CUR could improve the morphology and histopathology of the brain, inhibit Aβ aggregation and cell apoptosis, and maintain MSR balance at least partly by modulating the JMJD3-H3K27me3-BDNF axis. To sum up, moderate and high doses of CUR regulate the progression of AD via MSR JMJD3-H3K27me3-BDNF axis.