Evaluation and targeting of amyloid precursor protein (APP)/amyloid beta (Aβ) axis in amyloidogenic and non-amyloidogenic pathways: A time outside the tunnel

In Alzheimer disease (AD), amyloid precursor protein (APP) and production of amyloid beta (Aβ) which is generated by amyloidogenic pathway is implicated in neurotoxicity and neuronal cell deaths. However, physiological Aβ level is essential to improves neuronal survival, attenuates neuronal apoptosis and has neuroprotective effect. In addition, physiological APP level has neurotrophic effect on the central nervous system (CNS). APP has a critical role in the brain growth and development via activation of long-term potentiation (LTP) and acceleration of neurite outgrowth. Moreover, APP is cleaved by α secretase to form a neuroprotective soluble APP alpha (sAPPα) in non-amyloidogenic pathway. Consequently, this mini-review purposes to highlight the possible beneficial role of APP and Aβ. In addition, this mini-review discussed the modulation of APP processing and Aβ production.

reduce Aβ generation by shifting APP processing toward non-amyloidogenic pathway in APPswe transgenic SH-SY5Y cells

BACKGROUND

Alzheimer's disease (AD) is the most common neurodegenerative disease. Deposition of amyloid β plaques (Aβ) is a central hallmark of AD. Accumulating evidence suggest that shifting amyloid precursor protein (APP) metabolism pathway to non-amyloidogenic ways and inducing autophagy play key roles in AD pathology. In published reports, there is no research on the APP metabolic process of Terminalia chebula Retz. (T. Chebula).

PURPOSE

The study aims to assess the effects of T. Chebula in AD transgenic SH-SY5Y cells to determine its underlying mechanisms on reducing Aβ level by regulating APP metabolic process.

METHODS

The effects of T. Chebula water extract (TWE) on APPswe transgenic SH-SY5Y cells were analyzed by cell viability. ELISA used to quantify extracellular Aβ_1-40 and Aβ_1-42 generations. Western blot and RT-PCR assays were chosen to detect the expression of proteins and genes. The acridine orange (AO) stain was used to label autophagic-vesicles.

RESULTS

Treatment with TWE significantly suppressed the Aβ_1-40 and Aβ_1-42 generations of APPswe transgenic cells. TWE inhibited amyloidogenic pathway by reducing BACE1 expression, and promote non-amyloidogenic pathway by inducing ADAM10 level of APP metabolism. Additionally, TWE induced autophagy in APPswe transgenic cells involved in APP metabolism to shift the balance to non-amyloidogenic pathway.

CONCLUSION

In summary, our finding first time expounded that TWE can inhibit the generation of Aβ_1-40 and Aβ_1-42 in APPswe transgenic SH-SY5Y cells, which were regulated APP metabolism tends to non-amyloid metabolism pathway and mediated by autophagy. The results presented a novel finding for AD treatment of traditional natural medicines.

Treadmill exercise decreases amyloid-β burden possibly via activation of SIRT-1 signaling in a mouse model of Alzheimer's disease

Accumulation of amyloid-β (Aβ) correlates significantly with progressive cognitive deficits, a main symptom of Alzheimer's disease (AD). Although treadmill exercise reduces Aβ levels, the molecular mechanisms underlying the effects are not fully understood. We hypothesize that treadmill exercise decreases Aβ production and alleviates cognitive deficits by activating the non-amyloidogenic pathway via SIRT-1 signaling. Treadmill exercise improved cognitive deficits and alleviated neurotoxicity. Most importantly, treadmill exercise increased SIRT-1 level, which subsequently resulted in increased ADAM-10 level by down-regulation of ROCK-1 and upregulation of RARβ, ultimately facilitating the non-amyloidogenic pathway. Treadmill exercise-induced activation in SIRT-1 level also elevated PGC-1α level and reduced BACE-1 and C-99 level, resulting in inhibition of the amyloidogenic pathway. Treadmill exercise may thus inhibit Aβ production via upregulation of SIRT-1, which biases amyloid precursor protein processing toward the non-amyloidogenic pathway. This study provides novel and valuable insight into the molecular mechanisms possibly by which treadmill exercise reduces Aβ production.