scholarly journals Effect of amyloid beta peptide on poly(ADP-ribose) polymerase activity in adult and aged rat hippocampus.

2000 ◽  
Vol 47 (3) ◽  
pp. 847-854 ◽  
Author(s):  
J B Strosznajder ◽  
H Jeśko ◽  
R P Strosznajder
Keyword(s):  
Free Radicals ◽  
Amyloid Beta ◽  
Polymerase Activity ◽  
Rat Hippocampus ◽  
Amyloid Beta Peptide ◽  
Direct Role ◽  
Nitric Oxide Synthase Inhibitor ◽  
Aged Rat ◽  
Beta Peptide ◽  
Parp Activity

It is suggested that the fibrillar amyloid beta peptide (A beta) in brain plays a direct role in neurodegeneration in Alzheimer's disease, probably through activation of reactive oxygen species formation. Free radicals and numerous neurotoxins elicit DNA damage that subsequently activates poly(ADP-ribose) polymerase (PARP, EC 2.4.2.30). In this study the effect of neurotoxic fragment (25-35) of full length A beta peptide on PARP activity in adult and aged rat hippocampus was investigated. In adult (4 month old) rat hippocampus the A beta 25-35 peptide significantly enhanced PARP activity by about 80% but had no effect on PARP activity in cerebral cortex and in hippocampus from aged (24-27 month old) rats. The effect of A beta peptide was reduced by half by the nitric oxide synthase inhibitor N-nitro-L-arginine. Stimulation of glutamate receptor(s) itself enhanced PARP activity by about 80% in adult hippocampus. However, A beta 25-35 did not exert any additional stimulatory effect. These results indicate that A beta, through NO and probably other free radicals, induces activation of DNA bound PARP activity exclusively in adult but not in aged hippocampus.

scholarly journals Amyloid Beta-Peptide Increases BACE1 Translation through the Phosphorylation of the Eukaryotic Initiation Factor-2α

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Pol Picón-Pagès ◽  
Daniela A. Gutiérrez ◽  
Alejandro Barranco-Almohalla ◽  
Giulia Crepin ◽  
Marta Tajes ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Free Radicals ◽  
Western Blot ◽  
Amyloid Beta ◽  
Initiation Factor ◽  
Amyloid Beta Peptide ◽  
Braak Stage ◽  
Eukaryotic Initiation Factor ◽  
Bace1 Expression ◽  
Beta Peptide

Alzheimer’s disease (AD) is tightly linked to oxidative stress since amyloid beta-peptide (Aβ) aggregates generate free radicals. Moreover, the aggregation of Aβ is increased by oxidative stress, and the neurotoxicity induced by the oligomers and fibrils is in part mediated by free radicals. Interestingly, it has been reported that oxidative stress can also induce BACE1 transcription and expression. BACE1 is the key enzyme in the cleavage of the amyloid precursor protein to produce Aβ, and the expression of this enzyme has been previously shown to be enhanced in the brains of Alzheimer’s patients. Here, we have found that BACE1 expression is increased in the hippocampi from AD patients at both the early (Braak stage II) and late (Braak stage VI) stages of the disease as studied by immunohistochemistry and western blot. To address the role of Aβ and oxidative stress in the regulation of BACE1 expression, we have analyzed the effect of subtoxic concentrations of Aβ oligomers (0.25 μM) and H2O2 (10 mM) on a human neuroblastoma cell line. Firstly, our results show that Aβ oligomers and H2O2 induce an increase of BACE1 mRNA as we studied by qPCR. Regarding BACE1 translation, it is dependent on the phosphorylation of the eukaryotic initiation factor 2α (eIF2α), since BACE1 mRNA bears a 5′UTR that avoids its translation under basal conditions. BACE1 5′UTR contains four upstream initiating codons (uAUGs), and its translation is activated when eIF2α is phosphorylated. Consistently, we have obtained that Aβ oligomers and H2O2 increase the levels of BACE1 and p-eIF2α assayed by western blot and confocal microscopy. Our results suggest that Aβ oligomers increase BACE1 translation by phosphorylating eIF2α in a process that involves oxidative stress and conforms a pathophysiological loop, where the Aβ once aggregated favors its own production continuously by the increase in BACE1 expression as observed in AD patients.

G-lymphatic, vascular and immune pathways for Aβ clearance cascade and therapeutic targets for Alzheimer’s disease

2020 ◽  
Vol 23 ◽  
Author(s):  
Saurav Chakraborty ◽  
Jyothsna ThimmaReddygari ◽  
Divakar Selvaraj
Keyword(s):  
Alzheimer Disease ◽  
Amyloid Precursor Protein ◽  
Amyloid Beta ◽  
Complement System ◽  
Therapeutic Targets ◽  
Neuronal Cell ◽  
Precursor Protein ◽  
Amyloid Beta Peptide ◽  
Beta Peptide ◽  
Immune Pathways

The Alzheimer disease is a age related neurodegenerative disease. The factors causing alzheimer disease are numerous. Research on humans and rodent models predicted various causative factors involved in Alzheimer disease progression. Among them, neuroinflammation, oxidative stress and apoptosis play a major role because of accumulation of extracellular amyloid beta peptides. Here, the clearance of amyloid beta peptide plays a major role because of the imbalance in the production and clearance of the amyloid beta peptide. Additionally, neuroinflammation by microglia, astrocytes, cytokines, chemokines and the complement system also have a major role in Alzheimer disease. The physiological clearance pathways involved in amyloid beta peptide are glymphatic, vascular and immune pathways. Amyloid precursor protein, low density lipoprotein receptor-related protein 1, receptor for advanced glycation end product, apolipoprotein E, clusterin, aquaporin 4, auto-antibodies, complement system, cytokines and microglia are involved in amyloid beta peptide clearance pathways across the blood brain barrier. The plaque formation in the brain by alternative splicing of amyloid precursor protein and production of misfolded protein results in amyloid beta agglomeration. This insoluble amyloid beta leads to neurodegenerative cascade and neuronal cell death occurs. Studies had shown disturbed sleep may be a risk factor for dementia and cognitive decline. In this review, the therapeutic targets for alzheimer disease via focussing on pathways for amyloid beta clearance are discussed.

Conformations and Biological Activities of Amyloid Beta Peptide 25-35

2009 ◽  
Vol 999 (999) ◽  
pp. 1-6 ◽  
Author(s):  
L. Millucci ◽  
L. Ghezzi ◽  
G. Bernardini ◽  
A. Santucci
Keyword(s):  
Amyloid Beta ◽  
Biological Activities ◽  
Amyloid Beta Peptide ◽  
Beta Peptide
Sign in / Sign up

Export Citation Format

Share Document