The Nonfibrillar Amyloid β‐Peptide Induces Apoptotic Neuronal Cell Death

Abstract

Abstract:The toxicity of the nonaggregated amyloid ␤-peptide (1-40) [A␤(1-40)] on the viability of rat cortical neurons in primary culture was investigated. We demonstrated that low concentrations of A␤ peptide, in a nonfibrillar form, induced a time-and dose-dependent apoptotic cell death, including DNA condensation and fragmentation. We compared the neurotoxicity of the A␤(1-40) peptide with those of several A␤-peptide domains, comprising the membrane-destabilizing C-terminal domain of A␤ peptide (e.g., amino acids 29 -40 and 29 -42). These peptides reproduced the effects of the (1-40) peptide, whereas mutant nonfusogenic A␤ peptides and the central region of the A␤ peptide (e.g., amino acids 13-28) had no effect on cell viability. We further demonstrated that the neurotoxicity of the nonaggregated A␤ peptide paralleled a rapid and stable interaction between the A␤ peptide and the plasma membrane of neurons, preceding apoptosis and DNA fragmentation. By contrast, the peptide in a fibrillar form induced a rapid and dramatic neuronal death mainly through a necrotic pathway, under our conditions. Taken together, our results suggest that A␤ induces neuronal cell death by either apoptosis and necrosis and that an interaction between the nonfibrillar C-terminal domain of the A␤ peptide and the plasma membrane of cortical neurons might represent an early event in a cascade leading to neurodegeneration. Key Words: Alzheimer's disease -Amyloid ␤-peptideApoptosis-Fusogenic peptides-Neurotoxicity-Cortical primary neurons.

Critical role of cPLA2 in Aβ oligomer-induced neurodegeneration and memory deficit

“…To overcome problems of peptide solubility at high concentrations, fresh peptide stock solutions were prepared at 5 mg/mL in the disaggregating solvent hexafluoro-2-propanol, as previously described (Pillot et al, 1999) and kept frozen at Ϫ80°C. For the incubation of peptides with neurons, aliquots of peptide stock solution were quickly dried under nitrogen and directly solubilized at the experimental concentrations into the culture medium.…”

“…Primary cultures of cortical neurons were prepared from mouse or rat fetuses dissected on embryonic Days 16 -17 according to Bouillot et al (1996) and Pillot et al (1999). Briefly, dissociated cells were plated at 1.5 ϫ 10 5 cells per cm 2 for mouse cells or at 5 ϫ 10 4 cells per cm 2 for rat cells in plastic dishes precoated with polyornithine (1.5 mg/mL).…”

“…Cell viability was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay as previously described (Pillot et al, 1999;Sponne et al, 2004). Cell nuclei were visualized using 4,6-diamidino-2-phenylindole (DAPI) staining (Sponne et al, 2004).…”

Amyloid β induces neuronal cell death through ROS-mediated ASK1 activation

“…[5][6][7] Several studies also suggest that Ab-induced oxidative stress leads to apoptotic neuronal cell death that can be inhibited by antioxidants. [7][8][9] Nitric oxide (NO) synthesized by NO synthases (NOSs) also appears to participate in the pathogenesis of AD. Pathologic studies have suggested a functional link between NO and AD, in that neurofibrillary tangles in AD brain contain inducible NOS and exhibit nitrotyrosine formation in proteins.…”

Re-mention of an old neurodegenerative disease: Alzheimer’s disease

“…It has been reported that A disturbs mitochondrial respiration and promotes the generation of reactive oxygen species (ROS) [33][34][35]. Furthermore, A-induced oxidative stress leads to neuronal cell death that can be inhibited by antioxidants [33,36,37]. Additionally, pathologic study has suggested that nitric oxide (NO) synthases (NOSs) also appeared to participate in the pathogenesis of AD [38], and PS1 mutation-induced neurotoxicity is inhibited by NOS inhibitors [39].…”