Magdalena Cieslik

Apoptosis inducing factor and lipoxygenases in mitochondrial function affected by beta-amyloid peptides

Background: Oxidative stress occurs early in the progression of Alzheimer’s disease (AD). Non-enzymatic modifications induced by oxidative stress may also arise from reaction with low Mw reactive carbonyl compounds such as glyoxal (GO), methylglyoxal (MGO) and malondialdehyde (MDA), resulting from damaged carbohydrates or unsaturated fatty acids leading to the formation of both adducts and cross-links denominated Advanced Glycation/Lipoxidation End products (AGE/ALEs). It has been described that pro-nerve growth factor (pro-NGF) has increased levels in Alzheimer’s Disease (AD) affected brains and is able to induce cell death in cultures, however the reason for these phenomena is still elusive. Methods: Post-mortem human brain samples of AD and control cases were obtained from the Institute of Neuropathology Brain Bank. Antibody against pro-NGF prodomain was made as described Beattie et al. Secondary antibodies (anti-mouse IgG-HRP and anti-rabbit IgG-HRP) were obtained from Amersham Biosciences (Piscataway, NJ). CEL, CML and AGEs specific monoclonal antibodies were purchased from TransGenic Inc., (Kobe). Protein immunodetection, Pro-NGF immunoprecipitation; expression, purification and refolding of pro-NGF from Escheria coli, modifications of rh-pro-NGF, isolation of Pro-NGF from human brain, cell cultures and treatments, detection of apoptosis in the cell cultures, pro-NGF in vivo administration, and behavioral tests were done. Results: We show that pro-NGF in human Alzheimer’s disease-affected hippocampus and entorhinal cortex is modified by advanced glycation and lipoxidation end-products (AGE/ ALEs) in a stage-dependent manner. These modifications block the proNGF processing to mature NGF (NGF), thus making the proneurotrophin especially effective in inducing apoptosis of PC12 cells in culture through p75NTR. The processing of AGE/ALE in vitro modified recombinant human pro-NGF (rh-pro-NGF) is severely impaired as evidenced by Western blot and by examining its physiological functionality in cell cultures. We also report that modified rh-pro-NGF as well as pro-NGF isolated from human brain affected by AD, cause impairment of learning tasks when administered intracerebroventricularly in mice that correlates with Alzheimer’s disease-associated learning impairment. Conclusions: The data we present here offer a novel pathway of ethiopathogenesis in Alzheimer’s disease caused by AGE/ALEs modification of pro-NGF.

AIF and PARP-1, the molecular targets for Amyloid beta-toxicity: Alzheimer's disease genetic mutation increases cells susceptibility to nitrosative stress

Background: Moderate to severe Alzheimer’s disease (AD) is characterized by a high degree of cognitive, functional, and behavioral dysfunction. There are relatively few treatments available for this stage of illness, and these appear to provide symptomatic benefit without altering the course of the disease. The most widespread symptomatic treatments for AD are acetylcholinesterase inhibitors, including donepezil, which provide temporary cognitive benefits. In addition to acetylcholinesterase inhibitors, several clinical studies have shown support for the use of the NMDA receptor antagonist memantine, either as monotherapy or in combination with a cholinesterase inhibitor for moderate to severe AD. Methods: In this study, a battery of cognitive tasks was used to test the effects of donepezil, memantine, and combined treatment in 3xTg-AD mice (PS1M146V, APPSwe and tauP301L). These transgenic mice develop both plaques and tangles in a region-specific and age-progressive manner, and also exhibit progressive learning deficits. Donepezil (1mg/kg/day), memantine (30mg/kg/day), donepezil-memantine combination, or vehicle (saline) were administered orally via drinking water to cohorts of adult (15 months of age; severe pathology) and young mice (6 months of age; mild pathology), for three months. Results: In both adult and young mice, memantine and donepezil-memantine combination treatment significantly improved spatial memory (both acquisition and retention), compared to the vehicle-treated animals, whereas donepezil improved the retention, but not acquisition, of spatial memory. Conclusions: These results suggest that memantine treatment, or combination therapy using donepezil and memantine, is more effective than donepezil monotherapy at improving cognitive performance in both young and old mice demonstrating cognitive deficits and AD-like pathology.