Marlene Jimenez Del Rio

Aβ[25–35] Peptide and Iron Promote Apoptosis in Lymphocytes by an Oxidative Stress Mechanism: Involvement of H2O2, Caspase-3, NF-κB, p53 and c-Jun

Abstract The Aβ deposition in the neuritic plaques is one of the major neuropathological hallmarks of the Alzheimer disease (AD). Studies in vitro have demonstrated that the Aβ 25–35 fragment, which contains the cytotoxic functional sequence of the amyloid peptide, induces neurotoxicity and cell death by apoptosis. Despite intense investigations, a complete picture of the precise molecular cascade leading to cell death in a single cellular model is still lacking. In this study, we provide evidence that Aβ 25–35 induce apoptosis either alone or in presence of iron in peripheral blood lymphocytes cells (PBL) in a concentration-dependent fashion by an oxidative stress mechanism involving: (1) the production of hydrogen peroxide (H 2 O 2 ), reflected by rhodamine-positive fluorescent cells, (2) activation and/or translocation of NF-κB, p53 and c-Jun transcription factors showed by immunocytochemical diaminobenzidine positive nuclei, (3) activation of NF-κB complex by electrophoretic mobility shift assay/immuno-blotting/and ammonium pyrrolidinedithiocarbamate (PDTC) inhibition, (4) caspase-3 activation, reflected by caspase Ac-DEVD-cho inhibition, (5) mRNA synthesis de novo according to actinomycin D cell death inhibition. These results are consistent with the notion that the Aβ 25–35 /H 2 O 2 generation precede the apoptotic process and that once H 2 O 2 is generated, it is able to trigger a specific cell death signalisation. Thus, taken together these results, we present a well-ordered cascade of the major molecular events leading PBL to apoptosis. These results may contribute to explain the importance of Aβ alone or in the presence of redox-available iron in association with Aβ plaques (and neurofibrillary tangles) in AD brains and the significant role played by H 2 O 2 as a second messenger of death signal in some degenerative diseases linked to oxidative stress stimuli.

Monoamine neurotoxins-induced apoptosis in lymphocytes by a common oxidative stress mechanism: involvement of hydrogen peroxide (H2O2), caspase-3, and nuclear factor kappa-B (NF-κB), p53, c-Jun transcription factors

The destruction of dopaminergic and serotonergic nerve cells by selective 6-hydroxydopamine (6-OHDA), 5,6-dihydroxytryptamine (5,6-DHT) and 5,7-dihydroxytryptamine (5,7-DHT), respectively, is a commonly used tool to investigate the mapping of neuronal pathways, elucidation of function and to mimic human neurodegenerative disease such as Parkinsons and Alzheimers diseases. Despite intense investigations, a complete picture of the precise molecular cascade leading to cell death in a single cellular model is still lacking. In this study, we provide evidence that 6-OHDA, 5,6- and 5,7-DHT toxins-induced apoptosis in peripheral blood lymphocytes cells in a concentration-dependent fashion by a common oxidative mechanism involving: (1) the oxidation of toxins into quinones and production of the by-product hydrogen peroxide, reflected by desipramine-a monoamine uptake blocker-and antioxidants inhibition, (2) activation and/or translocation of nuclear factor-kappaB, p53 and c-Jun transcription factors, showed by immunocytochemical diaminobenzidine-positive stained nuclei, (3) caspase-3 activation, reflected by caspase Ac-DEVD-CHO inhibition, (4) mRNA and protein synthesis de novo according to cycloheximide and actinomycin D cell death inhibition. These results are consistent with the notion that uptake and intracellular autoxidation of those toxins precede the apoptotic process and that once H(2)O(2) is generated, it is able to trigger a specific cell death signalisation. Thus, taken together these results, we present an ordered cascade of the major molecular events leading peripheral blood lymphocytes to apoptosis. These results may contribute to explain the importance of H(2)O(2) as a second messenger of death signal in some degenerative diseases linked to oxidative stress stimuli.

CA1 Hippocampal Neuronal Loss in Familial Alzheimer's Disease Presenilin-1 E280A Mutation Is Related to Epilepsy

Summary:  Purpose: Alzheimer disease (AD) and epilepsy are brain disorders frequently associated with neuronal cell loss in mesial temporal lobe structures, but presenting different patterns of damage. Recently it was proposed that a causal relation may exist between AD pathology and the appearance of epilepsy in some cases with AD. This study aimed to determine the neuronal loss in CA1 hippocampal region from patients bearing the presenilin‐1 [E280A] mutation (PS1[E280A]) associated with seizures.

Paraquat induces apoptosis in human lymphocytes: Protective and rescue effects of glucose, cannabinoids and insulin-like growth factor-1

In order to establish causal or protective treatments for Parkinsons disease (PD), it is necessary to identify the cascade of deleterious events that lead to the dysfunction and death of dopaminergic neurons. Paraquat (PQ) is a pesticide used as xenobiotic compound to model PD. However, the mechanism(s) of PQ-induced cell death and the mechanism(s) of cytoprotection in a single cell model are still unknown. In this study, lymphocytes were treated with (0.1–1 mM) PQ. Apoptotic morphology was assessed with acridine orange/ethidium bromide staining. Further evaluation included (i) superoxide radicals, reflected by nitroblue tetrazolium reduction to formazan, (ii) the production of hydrogen peroxide, reflected by rhodamine-positive fluorescent cells, (iii) the generation of hydroxyl radicals, reflected by dimethylsulfoxide and melatonin √OH scavengers, (iv) activation and/or translocation of NF-κB, p53 and c-Jun transcription factors showed by immunocytochemical staining, and by ammonium pyrrolidinedithiocarbamate, pifithrin-α and SP600125 inhibition and (V) caspase-3 activation, reflected by caspase Ac-DEVD-cho inhibition. To elucidate the mechanism of cytoprotection, lymphocytes were treated with PQ in the presence of cannabinoids, insulin-like growth factor-1 and glucose. We provide evidence that PQ induces apoptosis in lymphocytes in a concentration- and time-dependent fashion by an oxidative stress mechanism involving O2√ − , H2O2/(√OH) generation, simultaneous activation of NF-κB/p53/c-Jun transcription factors, mitochondrial depolarization and caspase-3 activation leading to morphological apoptosis. Moreover, dying lymphocytes are protected and rescued from PQ noxious stimuli by direct antioxidant effect by cannabinoids, receptor mediated signaling by IGF-1, and/or energetic protection by glucose. It is concluded that PQ-induced apoptosis in lymphocytes by a mechanism involving reactive oxygen species generation, mitochondrial dysfunction, transcriptional factors and caspase-3 activation. However, this cell death routine can be reversed by the action of cannabinoids, IGF-1 and glucose. These data may provide innovating therapeutic strategies to intervene environmentally or genetically susceptible PD population to oxidative stress.

17β-Estradiol protects lymphocytes against dopamine and iron-induced apoptosis by a genomic-independent mechanism: Implication in Parkinson's disease

Dopamine (DA) in combination with iron (Fe(2+)) has been demonstrated to induce apoptosis in neuronal-like PC12 cells by an oxidative stress mechanism. To get a better insight of cell death and protective mechanisms in DA/Fe(2+)-induced toxicity, we investigated the effects of DA/Fe(2+) and the antioxidant action of 17 beta-estradiol (E2) in peripheral blood lymphocytes (PBL). We found that DA/Fe(2+)-induces apoptosis in PBL via a hydrogen peroxide (H(2)O(2))-mediated oxidative mechanism, which in turn triggers a cascade of molecular events requiring RNA and de novo protein synthesis. We have also demonstrated that E2 prevents significantly DA/Fe(2+)-induced apoptosis in PBL by directly inhibiting the intracellular accumulation of peroxides generated by DA/Fe(2+)-reaction. This protective activity is independent of the presence or activation of the estrogen receptors (ERs). These data further support and validate our previous hypothesis that DA/Fe(2+)/H(2)O(2) could be a general mediator of oxidative stress through a common cell death mechanism in both neuronal and nonneuronal cells. These findings may be particularly relevant to the potential approaches to rescue and prolong the survival of neurons by estrogens in patients with Parkinsons disease (PD).

Autosomal recessive juvenile parkinsonism Cys212Tyr mutation in parkin renders lymphocytes susceptible to dopamine- and iron-mediated apoptosis

Mutations in parkin are implicated in the pathogenesis of autosomal recessive juvenile parkinsonism (AR‐JP) disease. We show that homozygote Cys212Tyr parkin mutation in AR‐JP patients renders lymphocytes sensitive to dopamine, iron and hydrogen peroxide stimuli. Indeed, dopamine‐induced apoptosis by four alternative mechanisms converging on caspase‐3 activation and apoptotic morphology: (1) NF‐κB‐dependent pathway; mitochondrial dysfunction either by (2) H2O2 or (3) hydroxyl exposure and (4) increase of unfolded–protein stress. We also demonstrate that 17β‐estradiol and testosterone prevent homozygote lymphocytes from oxidative stressors‐evoked apoptosis. These results may contribute to understanding the relationship between genetic and environmental factors and iron in AR‐JP.

Familial Alzheimer’s Disease: Oxidative Stress, β-amyloid, Presenilins, and Cell Death

1. The basic etiology of Alzheimers disease remains unknown, although four genes have so far been involved: beta-amyloid precursor protein, presenilin-1, presenilin-2 and apolipoprotein E genes. 2. The largest familial Alzheimers disease (FAD) kindred so far reported belong to a point mutation in codon 280 that results in a glutamic acid-to-alanine substitution in presenilin-1 characterized in Antioquia, Colombia. 3. A hypothetical unified molecular mechanism model of cell death in FAD mediated by presenilin-1, beta-amyloid, and oxidative stress is proposed as an attempt to explain the mechanisms of neuronal loss in this neurodegenerative disorder.

New mutation (T1232P) of the ATP-7B gene associated with neurologic and neuropsychiatric dominance onset of Wilson’s disease in three unrelated Colombian kindred

Wilsons disease is an autosomal recessive disorder of hepatic copper metabolism caused by mutations in a gene encoding a copper-transporting P-type ATPase. We report the clinical and molecular characterization of six members from three unrelated Colombian kindred. Completed sequence DNA analysis linked to the gene ATP-7B from patient wd-1 revealed a novel A to C transversion in exon 17 at position 3856 (A3856C) of the ATP-7B mRNA resulting in a threonine for proline substitution at position 1232 of the ATP-7B protein (T1232P). Additionally, two novel polymorphisms were detected (2785G:Gly875 in exon 11; and intron at +38 a > c:tgcgcccga in exon 19). All affected individuals were homozygous for the T1232P mutation and displayed neurologic and neuropsychiatric dominant onset. This work expands the knowledge about the number, type, and implication of mutations in WD.