Mithramycin A Alleviates Cognitive Deficits and Reduces Neuropathology in a Transgenic Mouse Model of Alzheimer’s Disease

Increasing evidence has shown that specificity protein 1 (Sp1) is abnormally increased in the brains of subjects with Alzheimer’s disease (AD) and transgenic AD models. However, whether the Sp1 activation plays a critical role in the AD pathogenesis and selective inhibition of Sp1 activation may have a disease-modifying effect on the AD-like phenotypes remain elusive. In this study, we reported that Sp1 mRNA and protein expression were markedly increased in the brain of APPswe/PS1dE9 transgenic mice, whereas chronic administration of mithramycin A (MTM), a selective Sp1 inhibitor, potently inhibited Sp1 activation in the APPswe/PS1dE9 mice down to the levels of wild-type mice. Specifically, we found that MTM treatment resulted in a significant improvement of learning and memory deficits, a dramatic reduction in cerebral Aβ levels and plaque burden, a profound reduction in tau hyperphosphorylation, and a marked increase in synaptic marker in the APPswe/PS1dE9 mice. In addition, MTM treatment was powerfully effective in inhibiting amyloid precursor protein (APP) processing via suppressing APP, beta-site APP cleaving enzyme 1 (BACE1), and presenilin-1 (PS1) mRNA and protein expression to preclude Aβ production in the APPswe/PS1dE9 mice. Furthermore, MTM treatment strongly inhibited phosphorylated CDK5 and GSK3β signal pathways to reduce tau hyperphosphorylation in the APPswe/PS1dE9 mice. Collectively, our findings provide evidence that Sp1 activation may contribute to the AD pathogenesis and may serve as a novel therapeutic target in the treatment of AD. The present study highlights that selective Sp1 inhibitors may be considered as disease-modifying therapeutic agents for AD.