β-Amyloid 31-35

Alzheimer's disease is associated with the deposition of extracellular senile plaques, made primarily of amyloid-β (Aβ), particularly peptides Aβ1-42 and Aβ1-40. Neprilysin, or neutral endopeptidase (NEP), catalyzes proteolysis of the amyloid peptides (Aβ) and is recognized as one of the major regulators of the levels of these peptides in the brain, preventing Aβ accumulation and plaque formation. Here, we used a combination of techniques to elucidate the mechanism of Aβ binding and cleavage by NEP. Our findings indicate that the Aβ31-X cleavage products remain bound to the neprilysin active site, reducing proteolytic activity. Interestingly, it was already shown that this Aβ31-35 sequence is also critical for recognition of Aβ peptides by other targets, such as the serpin-enzyme complex receptor in neuronal cells.

Adiponectin is an adipocyte-derived hormone, which is closely associated with the development of Alzheimer's disease (AD) and has potential preventive and therapeutic significance. In the present study, we explored the relationship between adiponectin and circadian rhythm disorder in AD, the effect of adiponectin on the abnormal expression of Bmal1 mRNA/protein induced by amyloid-β protein 31-35 (Aβ31-35), and the underlying mechanism of action. We found that adiponectin-knockout mice exhibited amyloid-β deposition, circadian rhythm disorders and abnormal expression of Bmal1. Adiponectin ameliorated the abnormal expression of the Bmal1 mRNA/protein caused by Aβ31-35 by inhibiting the activity of glycogen synthase kinase 3β (GSK3β). These results suggest that adiponectin deficiency could induce circadian rhythm disorders and abnormal expression of the Bmal1 mRNA/protein, whilst exogenous administration of adiponectin may improve Aβ31-35-induced abnormal expression of Bmal1 by inhibiting the activity of GSK3β, thus providing a novel idea for the treatment of AD.

Amyloid β protein (Aβ) plays a critical role in pathogenesis of Alzheimer's disease (AD). Our previous studies indicated that the sequence 31-35 in Aβ molecule is an effective active center responsible for Aβ neurotoxicity in vivo and in vitro. In the present study, we prepared a novel antibody specifically targeting the sequence 31-35 of amyloid β protein, and investigated the neuroprotection of the anti-Aβ31-35 antibody against Aβ1-42 -induced impairments in neuronal viability, spatial memory, and hippocampal synaptic plasticity in rats. The results showed that the anti-Aβ31-35 antibody almost equally bound to both Aβ31-35 and Aβ1-42 , and pretreatment with the antibody dose-dependently prevented Aβ1-42 -induced cytotoxicity on cultured primary cortical neurons. In behavioral study, intracerebroventricular (i.c.v.) injection of anti-Aβ31-35 antibody efficiently attenuated Aβ1-42 -induced impairments in spatial learning and memory of rats. In vivo electrophysiological experiments further indicated that Aβ1-42 -induced suppression of hippocampal synaptic plasticity was effectively reversed by the antibody. These results demonstrated that the sequence 31-35 of Aβ may be a new therapeutic target, and the anti-Aβ31-35 antibody could be a novel immunotheraputic approach for the treatment of AD. © 2016 Wiley Periodicals, Inc.