FK506 reverses neuropathology and cognitive impairment in APPswe/PS1dE9 mice.

BACKGROUND: Alzheimer's disease (AD), a chronic and progressive neurodegenerative disease, is the most common cause of dementia. An important pathological basis for AD lesions is the excessive generation and deposition of β-amyloid (Aβ) caused by increased expression of the β-secretase, known as the β-site amyloid precursor protein cleaving enzyme 1 (BACE1). Effective suppression of the BACE1 overexpression has become a key AD treatment. Nuclear factor of activated T cells (NFAT) is a key transcription factor that regulates the expression of BACE1 in AD lesions, while Calcineurin (CaN) is a key regulatory protein that affects the transcription function of NFAT. Several lines of evidence have indicated that FK506 may promote the Aβ degradation via upregulation of the matrix metalloproteinase-9 (MMP-9) expression, which is associated with reduction of Aβ plaque deposition in the cerebral cortex and hippocampus.

METHODS: In this study, behavioral, histological, and biochemical methods were used to investigate the key role and molecular mechanisms of CaN inhibitor FK506 in cognitive dysfunction, regulation of BACE1 expression, and Aβ production in APPswe/PS1dE9 transgenic mice. Results The results indicate that FK506 inhibits NFAT1 levels in the cerebral cortex and hippocampus, thereby reducing the expression of BACE1 and mediating APP processing towards non-amyloidosis pathways, significantly reducing Aβ overproduction, which in turn saved cognitive deficits in APPswe/PS1dE9 transgenic mice. In addition, FK506 treatment had no significant effect on the expression of a disintegrin and metalloprotease (ADAM10) in α - secretase.

CONCLUSIONS: FK506 rescues cognitive deficits in APPswe/PS1dE9 mice by reducing Aβ production and deposition in the brain.