A Curcumin Analog Reduces Levels of the Alzheimer's Disease-Associated Amyloid-ß Protein by Modulating AßPP Processing and Autophagy.

Alzheimer's disease (AD) is a devastating neurodegenerative disease with no cure currently available. A pathological hallmark of AD is accumulation and deposition of amyloid-ß protein (Aß), a ∼4 kDa peptide generated through serial cleavage of the amyloid-ß protein precursor (AßPP) by ß- and γ-secretases. Curcumin is a natural compound primarily found in the widely used culinary spice, turmeric, which displays therapeutic potential for AD. Recently, we reported the development of curcumin analogs and identified a lead compound, curcumin-like compound-R17 (CLC-R17), that significantly attenuates Aß deposition in an AD transgenic mouse model. Here, we elucidated the mechanisms of this analog on Aß levels and AßPP processing using cell models of AD. Using biochemical methods and our recently developed nanoplasmonic fiber tip probe technology, we showed that the lead compound potently lowers Aß levels in conditioned media and reduces oligomeric amyloid levels in the cells. Furthermore, like curcumin, the lead compound attenuates the maturation of AßPP in the secretory pathway. Interestingly, it upregulated α-secretase processing of AßPP and inhibited ß-secretase processing of AßPP by decreasing BACE1 protein levels. Collectively, our data reveal mechanisms of a promising curcumin analog in reducing Aß levels, which strongly support its development as a potential therapeutic for AD.

Significant Upregulation of Alzheimer's ß-Amyloid Levels in a Living System Induced by Extracellular Elastin Polypeptides.

Alzheimer's disease (AD) is a neurodegenerative disorder and the primary cause of age-related dementia. The etiology of AD is complex and has not been completely elucidated. Herein, we report that treatment with elastin-like polypeptides (ELPs), a component of the brain extracellular matrix (ECM), significantly increased the levels of AD-related amyloid-ß peptides (Aß) both in vitro and in vivo. Regarding the molecular mechanism(s), the upregulation of Aß levels was related to increased proteolytic processing of the amyloid precursor protein. Furthermore, nesting tests demonstrated that the ELP-treated animals showed significant neurobehavioral deficits with cognitive impairment. These results suggest that the elastin is associated with AD-related pathological and behavioral changes. This finding presents a new aspect for Alzheimer's amyloidosis event and provides a great promise in developing ELP-based model systems to better understand the pathogenesis of AD.