The cerebral proteopathies

The abnormal assembly and deposition of specific proteins in the brain is the probable cause of most neurodegenerative disease afflicting the elderly. These “cerebral proteopathies” include Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), prion diseases, and a variety of other disorders. Evidence is accumulating that the anomalous aggregation of the proteins, and not a loss of protein function, is central to the pathogenesis of these diseases. Thus, therapeutic strategies that reduce the production, accumulation, or polymerization of pathogenic proteins might be applicable to a wide range of some of the most devastating diseases of old age.     

神经退化性疾病生物能量代谢和氧化应激研究进展

衰老是导致几种常见的神经系统退化性疾病的主要危险因素,包括帕金森氏病（Ｐａｒｋｉｎｓｏｎ’ｓ ｄｉｓｅａｓｅ ＰＤ）,肌萎缩性侧索硬化（Ａｍｙｏｔｒｏｐｈｉｃ ｌａｔｅｒａｌ ｓｃｌｅｒｏｓｉｓ,ＡＬＳ）,早老性痴呆（Ａｌｚｈｅｉｍｅｒ’ｓ ｄｉｓｅａｓｅ ＡＤ）和亨廷顿氏病（Ｈｕｎｔｉｎｇｔｏｎ’ｓ ｄｉｓｅａｓｅ ＨＤ）。最近研究表明,神经退化性疾病涉及到线粒体缺陷,氧化应激等因素。在脑和其它组织中,老化可导致线粒体功能的损伤和氧化损伤的增强。ＰＤ病人中,已发现线粒体复合酶体Ⅰ活性降低,氧化损伤增加和抗氧化系统活性的改变。在几例家族性ＡＬＳ病人中,也发现Ｃｕ、Ｚｎ超氧化物歧化酶（Ｃｕ,Ｚｎ ＳＯＤ）基因的突变,导致Ｃｕ、Ｚｎ超氧化物歧化酶活性减低;散发的ＡＬＳ病人氧化损伤增高。在ＨＤ病人中已发现能量代谢异常     

Protective Effects of Asiatic Acid on Rotenone- or H<Subscript>2</Subscript>O<Subscript>2</Subscript>-Induced Injury in SH-SY5Y Cells

Parkinson’s disease (PD) is a progressive neurodegenerative disorder with a prevalence of 1–2% in people over the age of 50. Mitochondrial dysfunction occurred in PD patients showing a 15–30% loss of activity in complex I. Asiatic acid (AA), a triterpenoid, is an antioxidant and used for depression treatment, but the effect of AA against PD-like damage has never been reported. In the present study, we investigated the protective effects of AA against H₂O₂ or rotenone-induced cellular injury and mitochondrial dysfunction in SH-SY5Y cells. Mitochondrial membrane potential (MMP) and the expression of voltage-dependent anion channel (VDAC) were detected with or without AA pretreatment following cellular injury to address the possible mechanisms of AA neuroprotection. The results showed that pre-treatment of AA (0.01–100 nM) protected cells against the toxicity induced by rotenone or H₂O₂. In addition, MMP dissipation occurred following the exposure of rotenone, which could be prevented by AA treatment. More interestingly, pre-administration of AA inhibited the elevation of VDAC mRNA and protein levels induced by rotenone(100 nM) or H₂O₂ (300 μM).These data indicate that AA could protect neuronal cells against mitochondrial dysfunctional injury and suggest that AA might be developed as an agent for PD prevention or therapy. Special issue article in honor of Dr. Akitane Mori.     

Natural Antioxidants Protect Neurons in Alzheimer’s Disease and Parkinson’s Disease

“Modern” medicine and pharmacology require an effective medical drug with a single compound for a specific disease. This seams very scientific but usually has unavoidable side effects. For example, the chemical therapy to cancer can totally damage the immunological ability of the patient leading to death early than non-treatment. On the other hand, natural antioxidant drugs not only can cure the disease but also can enhance the immunological ability of the patient leading to healthier though they usually have several compounds or a mixture. For the degenerative disease such as Alzheimer’s disease (AD) and Parkinson’s disease (PD), natural antioxidant drugs are suitable drugs, because the pathogenesis of these diseases is complex with many targets and pathways. These effects are more evidence when the clinic trial is for long term treatment. The author reviews the studies on the protecting effects of natural antioxidants on neurons in neurodegenerative diseases, especially summarized the results about protective effect of green tea polyphenols on neurons against apoptosis of cellular and animal PD models, and of genestine and nicotine on neurons against Aβ—induced apoptosis of hippocampal neuronal and transgenic mouse AD models. Special issue in honor of Dr. Akitane Mori.     

Features of ceruloplasmin in the cerebrospinal fluid of Alzheimer’s disease patients

The level of the apo-form of the copper enzyme ceruloplasmin (CP) is an established peripheral marker in diseases associated with copper imbalance. In view of the proposal that disturbances of copper homeostasis may contribute to neurodegeneration associated with Alzheimer’s disease (AD), the present work investigates, by Western blot and non-reducing SDS-PAGE followed by activity staining, the features of CP protein, and the copper/CP relationship in cerebrospinal fluid (CSF) and serum of AD patients. Results show that only a fraction of total copper is associated with CP in the CSF, at variance with serum, both in affected and in healthy individuals. Furthermore, a conspicuous amount of apo-ceruloplasmin and a decrease of CP oxidase activity characterize the CSF of the affected individuals, and confirm that an impairment of copper metabolism occurs in their central nervous system. In the CSF of AD patients the decrease of active CP, associated with the increase in the pool of copper not sequestered by this protein, may play a role in the neurodegenerative process.     

Genes and the Environment in Neurodegeneration

Neurodegenerative diseases are a heterogeneous group of pathologies which includes complex multifactorial diseases, monogenic disorders and disorders for which inherited, sporadic and transmissible forms are known. Factors associated with predisposition and vulnerability to neurodegenerative disorders may be described usefully within the context of gene–environment interplay. There are many identified genetic determinants for neurodegeneration, and it is possible to duplicate many elements of recognized human neurodegenerative disorders in animal models of the disease. However, there are similarly several identifiable environmental influences on outcomes of the genetic defects; and the course of a progressive neurodegenerative disorder can be greatly modified by environmental elements. In this review we highlight some of the major neurodegenerative disorders (Alzheimer’s disease, Parkinson’s disease, Amyotrophic lateral sclerosis, Huntington’s disease, and prion diseases.) and discuss possible links of gene–environment interplay including, where implicated, mitochondrial genes.     

Amyloid β-protein toxicity and oxidative stress in Alzheimer’s disease

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by loss of memory and progressive decline of cognitive abilities. Although the pathogenesis of this disease is not known and is still under intensive investigation, there are several hypotheses which address certain aspects of the disease. This review focuses on the oxidative-stress hypothesis of AD and on novel antioxidative approaches to an effective neuroprotection for the prevention and therapy of this neurodegenerative disorder. The toxicity of the AD-associated amyloid β-protein (Aβ), the induction of oxidative stress by Aβ in neurons, and potential sources of oxidative events in brain tissue are discussed. Received: 20 February 1997 / Accepted: 9 May 1997     

Hallmarks of protein oxidative damage in neurodegenerative diseases: focus on Alzheimer’s disease

Summary. The pathogenesis of several neurodegenerative diseases, including Alzheimer’s disease, has been linked to a condition of oxidative and nitrosative stress, arising from the imbalance between increased reactive oxygen species (ROS) and reactive nitrogen species (RNS) production and antioxidant defences or efficiency of repair or removal systems. The effects of free radicals are expressed by the accumulation of oxidative damage to biomolecules: nucleic acids, lipids and proteins. In this review we focused our attention on the large body of evidence of oxidative damage to protein in Alzheimer’s disease brain and peripheral cells as well as in their role in signalling pathways. The progress in the understanding of the molecular alterations underlying Alzheimer’s disease will be useful in developing successful preventive and therapeutic strategies, since available drugs can only temporarily stabilize the disease, but are not able to block the neurodegenerative process.     

Modeling human neurodegenerative diseases in transgenic systems

Transgenic systems are widely used to study the cellular and molecular basis of human neurodegenerative diseases. A wide variety of model organisms have been utilized, including bacteria (Escherichia coli), plants (Arabidopsis thaliana), nematodes (Caenorhabditis elegans), arthropods (Drosophila melanogaster), fish (zebrafish, Danio rerio), rodents (mouse, Mus musculus and rat, Rattus norvegicus) as well as non-human primates (rhesus monkey, Macaca mulatta). These transgenic systems have enormous value for understanding the pathophysiological basis of these disorders and have, in some cases, been instrumental in the development of therapeutic approaches to treat these conditions. In this review, we discuss the most commonly used model organisms and the methodologies available for the preparation of transgenic organisms. Moreover, we provide selected examples of the use of these technologies for the preparation of transgenic animal models of neurodegenerative diseases, including Alzheimer’s disease (AD), frontotemporal lobar degeneration (FTLD), amyotrophic lateral sclerosis (ALS), Huntington’s disease (HD) and Parkinson’s disease (PD) and discuss the application of these technologies to AD as an example of how transgenic modeling has affected the study of human neurodegenerative diseases.     

Applications of neutron activation analysis to the study of age-related neurological diseases

Although the etiology and pathogenesis of Alzheimer’s disease, Pick’s disease, and amyotrophic lateral sclerosis are still unknown, it has been suggested that perturbations in element metabolism may play a role. Even if not causative factors, these imbalances may prove to be markers that could aid in diagnosis. We have employed a sequential neutron activation analysis (NAA) procedure to determine elemental concentrations in brain, hair, fingernails, blood, and cerebrospinal fluid (CSF) of these patients and age-matched controls. Samples are first irradiated with accelerator-produced 14-MeV neutrons for determination of nitrogen and phosphorus, then with reactor thermal neutrons for the instrumental determination of 16–18 minor and trace elements, and, finally, reactor-irradiated again, followed by a rapid radiochemical separation procedure (RNAA) to determine four additional elements. Major advantages of NAA are: (1) its simultaneous multielement capability; (2) the relative freedom from reagent and laboratory contamination; (3) the absence of major matrix effects; and (4) an adequate sensitivity for most elements of interest. Ranges of concentrations by INAA and RNAA in selected control tissues and interelement correlations in control brain are presented to illustrate results obtained by the procedure. Longitudinal studies of tissues from Alzheimer’s disease (AD) and amyotrophic lateral sclerosis (ALS) patients are still in progress.     

Increased Caspase-2, Calpain Activations and Decreased Mitochondrial Complex II Activity in Cells Expressing Exogenous Huntingtin Exon 1 Containing CAG Repeat in the Pathogenic Range

(1) Huntington’s disease (HD) is an autosomal dominant neurodegenerative disease caused by the expansion of polymorphic CAG repeats beyond 36 at exon 1 of huntingtin gene (htt). To study cellular effects by expressing N-terminal domain of Huntingtin (Htt) in specific cell lines, we expressed exon 1 of htt that codes for 40 glutamines (40Q) and 16Q in Neuro2A and HeLa cells. (2) Aggregates and various apoptotic markers were detected at various time points after transfection. In addition, we checked the alterations of expressions of few apoptotic genes by RT-PCR. (3) Cells expressing exon 1 of htt coding 40Q at a stretch exhibited nuclear and cytoplasmic aggregates, increased caspase-1, caspase-2, caspase-8, caspase-9/6, and calpain activations, release of cytochrome c and AIF from mitochondria in a time-dependent manner. Truncation of Bid was increased, while the activity of mitochondrial complex II was decreased in such cells. These changes were significantly higher in cells expressing N-terminal Htt with 40Q than that obtained in cells expressing N-terminal Htt with 16Q. Expressions of caspase-1, caspase-2, caspase-3, caspase-7, and caspase-8 were increased while expression of Bcl-2 was decreased in cells expressing mutated Htt-exon 1. (4) Results presented in this communication showed that expression of mutated Htt-exon 1 could mimic the cellular phenotypes observed in Huntington’s disease and this cell model can be used for screening the agents that would interfere with the apoptotic pathway and aggregate formation.     

Role of Nitric Oxide Synthases in Parkinson’s Disease: A Review on the Antioxidant and Anti-inflammatory Activity of Polyphenols

Natural polyphenols can exert protective action on a number of pathological conditions including neurodegenerative disorders. The neuroprotective effects of many polyphenols rely on their ability to permeate brain barrier and here directly scavenge pathological concentration of reactive oxygen and nitrogen species and chelate transition metal ions. Importantly, polyphenols modulate neuroinflammation by inhibiting the expression of inflammatory genes and the level of intracellular antioxidants. Parkinson’s disease (PD) is a neurodegenerative disorder characterized by several abnormalities including inflammation, mitochondrial dysfunction, iron accumulation and oxidative stress. There is considerable evidence showing that cellular oxidative damage occurring in PD might result also from the actions of altered production of nitric oxide (NO). Indeed, high levels of neuronal and inducible NO synthase (NOS) were found in substantia nigra of patients and animal models of PD. Here, we evaluate the involvement of NOS/NO in PD and explore the neuroprotective activity of natural polyphenol compounds in terms of anti-inflammatory and antioxidant action. Special issue article in honor of Dr. Anna Maria Giuffrida-Stella.     

Modulation of α-Synuclein Aggregation by Dopamine: A Review

Parkinson’s disease (PD) is a progressive neurodegenerative disorder that is characterized by (1) the selective loss of dopaminergic neurons in the substantia nigra and (2) the deposition of misfolded α-synuclein (α-syn) as amyloid fibrils in the intracellular Lewy bodies in various region of the brain. Current thinking suggests that an interaction between α-syn and dopamine (DA) leads to the selective death of neuronal cells and the accumulation of misfolded α-syn. However, the exact mechanism by which this occurs is not fully defined. DA oxidation could play a key role is the pathogenesis of PD by causing oxidative stress, mitochondria dysfunction and impairment of protein metabolism. Here, we review the literature on the role of DA and its oxidative intermediates in modulating the aggregation pathways of α-syn.     

Flavonoid Baicalein Modulates H<Subscript>2</Subscript>O<Subscript>2</Subscript>-Induced Mitogen-Activated Protein Kinases Activation and Cell Death in SK-N-MC Cells

It is believed that ROS-induced oxidative stress triggers numerous signaling pathways which are involved in neurodegenerative diseases, including Alzheimer’s disease. To find the effective drugs for neurodegenerative diseases, the deep delve into molecular mechanisms underlie these diseases is necessary. In the current study, we investigated the effects of flavonoid baicalein on H₂O₂-induced oxidative stress and cell death in SK-N-MC cells. Our results revealed that the treatment of SK-N-MC cells with H₂O₂ led to a decrease in cell viability through phosphorylation and activation of extracellular signal-regulated kinases (ERKs) and c-Jun N-terminal kinases (JNKs) pathways followed by increase in Bax/Bcl2 ratio and initiation of caspase-dependent apoptotic pathways. In addition, our results showed that the exposure of SK-N-MC cells to H₂O₂ ended up in reduction of glutathione (GSH) levels of SK-N-MC cells via JNK/ERK-mediated down-regulation of γ-glutamyl-cysteine synthetase (γ-GCS) expression. Our results demonstrated that flavonoid baicalein protected against H₂O₂-induced cell death by inhibition of JNK/ERK pathways activation and other key molecules in apoptotic pathways, including blockage of Bax and caspase-9 activation, induction of Bcl-2 expression and prevention of cell death. Baicalein supported intracellular defense mechanisms through maintaining GSH levels in SK-N-MC cells by the removal of inhibition effects of JNK/ERK pathways from γ-GCS expression. In addition, baicalein attenuated lipid and protein peroxidation and intracellular reactive oxygen species in SK-N-MC cells. In accordance with these observations, baicalein can be a promising candidate in antioxidant therapy and designing of natural-based drug for ROS-induced neurodegenerative disorders.     

Cell death pathways in Parkinson’s disease: proximal triggers, distal effectors, and final steps

Parkinson’s disease (PD) is a common neurodegenerative disorder. Neuronal cell death in PD is still poorly understood, despite a wealth of potential pathogenic mechanisms and pathways. Defects in several cellular systems have been implicated as early triggers that start cells down the road toward neuronal death. These include abnormal protein accumulation, particularly of alpha-synuclein; altered protein degradation via multiple pathways; mitochondrial dysfunction; oxidative stress; neuroinflammation; and dysregulated kinase signaling. As dysfunction in these systems mounts, pathways that are more explicitly involved in cell death become recruited. These include JNK signaling, p53 activation, cell cycle re-activation, and signaling through bcl-2 family proteins. Eventually, neurons become overwhelmed and degenerate; however, even the mechanism of final cell death in PD is still unsettled. In this review, we will discuss cell death triggers and effectors that are relevant to PD, highlighting important unresolved issues and implications for the development of neuroprotective therapies.     

Metalloproteinase’s Activity and Oxidative Stress in Mild Cognitive Impairment and Alzheimer’s Disease

Matrix metalloproteinases (MMPs) and oxidative stress have been implicated in neurological diseases such as Alzheimer’s disease (AD). Plasma MMP-2 and MMP-9 activities were assessed in Mild Cognitive Impairment (MCI) and AD subjects compared with aged-matched controls, and subsequently analysed in relation to oxidative stress markers. Both MMP-2 and MMP-9 showed no significant changes versus control subjects. Plasma glutathione peroxidase Se-dependent (GPx-Se) activity and malondialdehyde (MDA) levels were higher in AD than in controls (P < 0.05), suggesting a role for GPx-Se in controlling oxidative stress in AD. Negative correlations were observed between MMPs and MDA in AD and MCI patients (P < 0.05). In conclusion, oxidative stress events did not include activation of MMPs and this similar pattern in AD and MCI suggests that both are biochemically equivalent.     

Oxidative stress in brain aging, neurodegenerative and vascular diseases: an overview

According to the free radical theory, aging can be considered as a progressive, inevitable process partially related to the accumulation of oxidative damage into biomolecules -- nucleic acids, lipids, proteins or carbohydrates -- due to an imbalance between prooxidants and antioxidants in favor of the former. More recently also the pathogenesis of several diseases has been linked to a condition of oxidative stress. In this review we focus our attention on the evidence of oxidative stress in aging brain, some of the most important neurodegenerative diseases -- Alzheimer's disease (AD), mild cognitive impairment (MCI), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD) -- and in two common and highly disabling vascular pathologies--stroke and cardiac failure. Particular attention will be given to the current knowledge about the biomarkers of oxidative stress that can be possibly used to monitor their severity and outcome.     

Glutathionylation of the Pro-apoptotic Protein p53 in Alzheimer’s Disease Brain: Implications for AD Pathogenesis

Alzheimer’s disease (AD) is an age-related neurodegenerative disorder. The exact mechanism for the AD pathogenesis is not clearly understood. However, a number of hypotheses have been proposed to explain the pathogenesis of AD. One the hypotheses is the oxidative stress hypothesis that is supported by a number of studies which reported an increase in the levels of reactive oxygen/reactive nitrogen species and their products with a concomitant decrease in the levels of antioxidant enzymes in AD brain. In the present study, we measured in AD brain the expression levels of different forms (monomer, dimer and tetramer) of the pro-apoptotic protein, p53, and observed greater levels of p53 monomer and dimer in AD brain compared to control. In addition, we also showed the selective glutathionylation of monomeric and dimeric form of p53 in AD brain. We propose that glutathionylation of p53 may prevent the formation of tetramer, an aggregate form required for effective action of p53, and may be involved in oxidative stress conditions and neurodegeneration observed in this dementing disorder. Special issue article in Honour of Dr. Akitane Mori. Fabio Di Domenico and Giovanna Cenini contributed equally. An erratum to this article can be found at     

Role of Tuberin in Neuronal Degeneration

One of the tuberous sclerosis complex (TSC) gene products, tuberin is assumed to be the functional component, being involved in a wide variety of cellular processes. Here, we report for the first time that tuberin dysfunction may represent a mechanism for neuronal damage in Alzheimer’s disease (AD), Parkinson’s disease with dementia (PD/DLB), and a mouse model of PD. Tuberin was hyperphosphorylated at Thr1462 in post-mortem frontal cortex tissue of both AD and PD/DLB patients and in mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP). Both PTEN and Akt phosphoactivation corresponded to the hyperphosphorylation patterns of tuberin suggesting that the PTEN–Akt pathway might be the mechanism of tuberin phosphorylation. Our data provide new information regarding the possible role of tuberin dysfunction in major neurodegenerative disorders, such as AD and PD, whereby inhibition of tuberin function may trigger an onset of neuronal cell death.