Effects of Newly Synthesized Recombinant Human Amyloid-�� Complexes and Poly-Amyloid-�� Fibers on Cell Apoptosis and Cognitive Decline

Abstract

The main pathological hallmark of Alzheimer's disease is the deposition of amyloid-beta (Aβ) peptides in the brain. Aβ has been widely used to mimic several aspects of Alzheimer's disease. However, several characteristics of amyloid-induced Alzheimer's disease pathology are not well established, especially in mice. The present study aimed to develop a new Alzheimer's disease model by investigating how Aβ can be effectively aggregated using prokaryotes and eukaryotes. To express the Aβ42 complex in HEK293 cells, we cloned the Aβ42 region in a tandem repeat and incorporated the resulting construct into a eukaryotic expression vector. Following transfection into HEK293 cells via lipofection, cell viability assay and western blotting analysis revealed that exogenous Aβ42 can induce cell death and apoptosis. In addition, recombinant His-tagged Aβ42 was successfully expressed in BL21 (DE3) and not only readily formed Aβ complexes, but also inhibited the proliferation of SH-SY5Y cells and. For in vivo testing, recombinant His-tagged Aβ42 solution (3 μg/μl in 1× PBS containing 1 mM Ni²⁺) was injected stereotaxically into the left and right lateral ventricles of the brains of C57BL/6J mice ( = 8). Control mice were injected with 1× PBS containing 1 mM Ni²⁺ following the same procedure. Ten days after the sample injection, the Morris water maze test confirmed that exogenous Aβ caused an increase in memory loss. These findings demonstrated that Ni²⁺ is capable of complexing the 50-kDa amyloid and that intracerebroventricular injection of Aβ42 can lead to cognitive impairment, thereby providing improved Alzheimer's disease models.

Pharmacological Basis for the Use of Evodiamine in Alzheimer’s Disease: Antioxidation and Antiapoptosis

“…The increased level of Aβ42 in the cerebral cortex is a striking feature of AD [ 2 ]. Low levels of Aβ42 in serum ( p < 0.01; Figure 5 A) and high levels of Aβ42 in the cerebral cortex ( p < 0.01; Figure 5 B) were found in AD mice.…”

“…Intracellular NFTs are formed by atypical hyperphosphorylation of tau protein, and ultimately lead to apoptosis and neuronal loss. 42-amino-acid Aβ peptide derived from amyloid precursor protein (APP) is one of the major components of neuritic plaques [ 2 ]. The preferential deposition of Aβ42 is attributed to the extended form of COOH of the peptide.…”

“…Aβ42 is less soluble than Aβ40 and more readily aggregates and forms anti-parallel β-pleated sheets. Aβ42 can also act as seeds to initiate Aβ40 aggregation [ 2 ]. Protein oxidation caused by ROS leads to polymerization, thereby forming protein aggregation, such as Aβ deposition [ 36 ].…”

“…Alzheimer’s disease (AD), a chronic and progressive neurodegenerative disorder generally related to ageing, is characterized by cognitive dysfunction, impaired memory, and poor prognosis [ 1 ]. Although the pathological cause of AD is still mostly unknown, past findings have proven that patients with AD show an accumulation of abnormally folded beta-amyloid (Aβ) in senile plaques and neuronal apoptosis [ 2 ]. Oxidative stress has been reported as one of the key causes of neuronal apoptosis during the development of AD, which is associated with the remarkable accumulation of reactive oxygen species (ROS), mitochondrial dysfunction, and calcium accumulation [ 3 ].…”

Age-Related Increase of Insulin-Degrading Enzyme Is Inversely Correlated with Cognitive Function in APPswe/PS1dE9 Mice

“…Aβ plaques are one of the most important risk factors of advanced cognitive impairment in the pathogenesis of AD. They can be produced by neuronal cells and peripheral cells [ 36 ]. Almost all patients with Alzheimer’s disease, which includes familial AD and sporadic AD, have Aβ plaques deposited in brain tissue.…”