Acrolein induces selective protein carbonylation in synaptosomes

Role of reactive carbonyls and superoxide radicals in protein damage by cigarette smoke extracts: Comparison of Heat-not-Burn e-cigarettes to conventional cigarettes

Oxidative protein damage involving carbonylation of respiratory tract proteins typically accompanies exposure to tobacco smoke. Such damage can arise via multiple mechanisms, including direct amino acid oxidation by reactive oxygen species or protein adduction by electrophilic aldehydes. This study investigated the relative importance of these pathways during exposure of a model protein to fresh cigarette emission extracts. Briefly, protein carbonyl adducts were estimated in bovine serum albumin following incubation in buffered solutions with whole cigarette emissions extracts prepared from either a single 1R6F research cigarette or a single "Heat-not-Burn" e-cigarette. Although both extracts caused concentration-dependent protein carbonylation, conventional cigarette extracts produced higher adduct yields than e-cigarette extracts. Superoxide radical generation by conventional and e-cigarette emissions was assessed by monitoring nitro blue tetrazolium reduction and was considerably lower in extracts made from "Heat-Not-Burn" e-cigarettes. The superoxide dismutase/catalase mimic EUK-134 strongly suppressed radical production by whole smoke extracts from conventional cigarettes, however, it did not diminish protein carbonyl adduction when incubating smoke extracts with the model protein. In contrast, edaravone, a neuroprotective drug with strong carbonyl-trapping properties, strongly suppressed protein damage without inhibiting superoxide formation. Although these findings require extension to appropriate cell-based and in vivo systems, they suggest reactive aldehydes in tobacco smoke make greater contributions to oxidative protein damage than smoke phase radicals.

The Role of Acrolein in Neurodegenerative Diseases and Its Protective Strategy

Neurodegenerative diseases are characterized by a massive loss of specific neurons, which can be fatal. Acrolein, an omnipresent environmental pollutant, is classified as a priority control contaminant by the EPA. Evidence suggests that acrolein is a highly active unsaturated aldehyde related to many nervous system diseases. Therefore, numerous studies have been conducted to identify the function of acrolein in neurodegenerative diseases, such as ischemic stroke, AD, PD, and MS, and its exact regulatory mechanism. Acrolein is involved in neurodegenerative diseases mainly by elevating oxidative stress, polyamine metabolism, neuronal damage, and plasma ACR-PC levels, and decreasing urinary 3-HPMA and plasma GSH levels. At present, the protective mechanism of acrolein mainly focused on the use of antioxidant compounds. This review aimed to clarify the role of acrolein in the pathogenesis of four neurodegenerative diseases (ischemic stroke, AD, PD and MS), as well as protection strategies, and to propose future trends in the inhibition of acrolein toxicity through optimization of food thermal processing and exploration of natural products.

Protein Oxidation in Muscle Foods: A Comprehensive Review

Muscle foods and their products are a fundamental part of the human diet. The high protein content found in muscle foods, as well as the high content of essential amino acids, provides an appropriate composition to complete the nutritional requirements of humans. However, due to their special composition, they are susceptible to oxidative degradation. In this sense, proteins are highly susceptible to oxidative reactions. However, in contrast to lipid oxidation, which has been studied in depth for decades, protein oxidation of muscle foods has been investigated much less. Moreover, these reactions have an important influence on the quality of muscle foods, from physico-chemical, techno-functional, and nutritional perspectives. In this regard, the loss of essential nutrients, the impairment of texture, water-holding capacity, color and flavor, and the formation of toxic substances are some of the direct consequences of protein oxidation. The loss of quality for muscle foods results in consumer rejection and substantial levels of economic losses, and thus the control of oxidative processes is of vital importance for the food industry. Nonetheless, the complexity of the reactions involved in protein oxidation and the many different factors that influence these reactions make the mechanisms of protein oxidation difficult to fully understand. Therefore, the present manuscript reviews the fundamental mechanisms of protein oxidation, the most important oxidative reactions, the main factors that influence protein oxidation, and the currently available analytical methods to quantify compounds derived from protein oxidation reactions. Finally, the main effects of protein oxidation on the quality of muscle foods, both from physico-chemical and nutritional points of view, are also discussed.

Carnosine quenches the reactive carbonyl acrolein in the central nervous system and attenuates autoimmune neuroinflammation

Background

Multiple sclerosis (MS) is a chronic autoimmune disease driven by sustained inflammation in the central nervous system. One of the pathological hallmarks of MS is extensive free radical production. However, the subsequent generation, potential pathological role, and detoxification of different lipid peroxidation-derived reactive carbonyl species during neuroinflammation are unclear, as are the therapeutic benefits of carbonyl quenchers. Here, we investigated the reactive carbonyl acrolein and (the therapeutic effect of) acrolein quenching by carnosine during neuroinflammation.

Methods

The abundance and localization of acrolein was investigated in inflammatory lesions of MS patients and experimental autoimmune encephalomyelitis (EAE) mice. In addition, we analysed carnosine levels and acrolein quenching by endogenous and exogenous carnosine in EAE. Finally, the therapeutic effect of exogenous carnosine was assessed in vivo (EAE) and in vitro (primary mouse microglia, macrophages, astrocytes).

Results

Acrolein was substantially increased in inflammatory lesions of MS patients and EAE mice. Levels of the dipeptide carnosine (β-alanyl-l-histidine), an endogenous carbonyl quencher particularly reactive towards acrolein, and the carnosine-acrolein adduct (carnosine-propanal) were ~ twofold lower within EAE spinal cord tissue. Oral carnosine treatment augmented spinal cord carnosine levels (up to > tenfold), increased carnosine-acrolein quenching, reduced acrolein-protein adduct formation, suppressed inflammatory activity, and alleviated clinical disease severity in EAE. In vivo and in vitro studies indicate that pro-inflammatory microglia/macrophages generate acrolein, which can be efficiently quenched by increasing carnosine availability, resulting in suppressed inflammatory activity. Other properties of carnosine (antioxidant, nitric oxide scavenging) may also contribute to the therapeutic effects.

Conclusions

Our results identify carbonyl (particularly acrolein) quenching by carnosine as a therapeutic strategy to counter inflammation and macromolecular damage in MS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02306-9.

Protein carbonylation in food and nutrition: a concise update

Protein oxidation is a topic of indisputable scientific interest given the impact of oxidized proteins on food quality and safety. Carbonylation is regarded as one of the most notable post-translational modifications in proteins and yet, this reaction and its consequences are poorly understood. From a mechanistic perspective, primary protein carbonyls (i.e. α-aminoadipic and γ-glutamic semialdehydes) have been linked to radical-mediated oxidative stress, but recent studies emphasize the role alternative carbonylation pathways linked to the Maillard reaction. Secondary protein carbonyls are introduced in proteins via covalent linkage of lipid carbonyls (i.e. protein-bound malondialdehyde). The high reactivity of protein carbonyls in foods and other biological systems indicates the intricate chemistry of these species and urges further research to provide insight into these molecular mechanisms and pathways. In particular, protein carbonyls are involved in the formation of aberrant and dysfunctional protein aggregates, undergo further oxidation to yield carboxylic acids of biological relevance and establish interactions with other biomolecules such as oxidizing lipids and phytochemicals. From a methodological perspective, the routine dinitrophenylhydrazine (DNPH) method is criticized not only for the lack of accuracy and consistency but also authors typically perform a poor interpretation of DNPH results, which leads to misleading conclusions. From a practical perspective, the biological relevance of protein carbonyls in the field of food science and nutrition is still a topic of debate. Though the implication of carbonylation on impaired protein functionality and poor protein digestibility is generally recognized, the underlying mechanism of such connections requires further clarification. From a medical perspective, protein carbonyls are highlighted as markers of protein oxidation, oxidative stress and disease. Yet, the specific role of specific protein carbonyls in the onset of particular biological impairments needs further investigations. Recent studies indicates that regardless of the origin (in vivo or dietary) protein carbonyls may act as signalling molecules which activate not only the endogenous antioxidant defences but also implicate the immune system. The present paper concisely reviews the most recent advances in this topic to identify, when applicable, potential fields of interest for future studies.

Chemical Depletion of Histidine-Containing Peptides Allows Identification of More Low-Abundance Methylation Sites from Proteome Samples

Protein methylation, especially that occurs on arginine and lysine residues, is one of the most important post-translational modifications involved in various cellular processes including RNA splicing, DNA repair, and so forth. Systematic analysis of protein methylation would facilitate the understanding of its regulatory mechanisms. Strong cation chromatography has been used to globally analyze arginine/lysine methylation at the proteome scale with good performance. However, the co-enriched histidine-containing peptides severely interfere with the detection of low-abundance methylpeptides. Here, we developed a novel chemical strategy which enabled almost complete depletion of histidine-containing peptides in the protein digest, thereby resulting in the identification of more low-abundance arginine/lysine methylpeptides. Totally, 333 arginine and lysine methylation forms from 207 proteins were identified in this study. Overall, the number of methylation identifications increased about 50% by using our new method. Data are available via ProteomeXchange with the identifier PXD023845.

VDAC1 at the Intersection of Cell Metabolism, Apoptosis, and Diseases

The voltage-dependent anion channel 1 (VDAC1) protein, is an important regulator of mitochondrial function, and serves as a mitochondrial gatekeeper, with responsibility for cellular fate. In addition to control over energy sources and metabolism, the protein also regulates epigenomic elements and apoptosis via mediating the release of apoptotic proteins from the mitochondria. Apoptotic and pathological conditions, as well as certain viruses, induce cell death by inducing VDAC1 overexpression leading to oligomerization, and the formation of a large channel within the VDAC1 homo-oligomer. This then permits the release of pro-apoptotic proteins from the mitochondria and subsequent apoptosis. Mitochondrial DNA can also be released through this channel, which triggers type-Ι interferon responses. VDAC1 also participates in endoplasmic reticulum (ER)-mitochondria cross-talk, and in the regulation of autophagy, and inflammation. Its location in the outer mitochondrial membrane, makes VDAC1 ideally placed to interact with over 100 proteins, and to orchestrate the interaction of mitochondrial and cellular activities through a number of signaling pathways. Here, we provide insights into the multiple functions of VDAC1 and describe its involvement in several diseases, which demonstrate the potential of this protein as a druggable target in a wide variety of pathologies, including cancer.

Determination of Protein Haptenation by Chemical Sensitizers Within the Complexity of the Human Skin Proteome

Skin sensitization associated with the development of allergic contact dermatitis occurs via a number of specific key events at the cellular level. The molecular initiating event (MIE), the first in the sequence of these events, occurs after exposure of the skin to an electrophilic chemical, causing the irreversible haptenation of proteins within skin. Characterization of this MIE is a key step in elucidating the skin sensitization adverse outcome pathway and is essential to providing parameters for mathematical models to predict the capacity of a chemical to cause sensitization. As a first step to addressing this challenge, we have exposed complex protein lysates from a keratinocyte cell line and human skin tissue with a range of well characterized sensitizers, including dinitrochlorobenzene, 5-chloro-2-methylisothiazol-3-one, cinnamaldehyde, and the non (or weak) sensitizer 6-methyl coumarin. Using a novel stable isotope labeling approach combined with ion mobility-assisted data independent mass spectrometry (HDMSE), we have characterized the haptenome for these sensitizers. Although a significant proportion of highly abundant proteins were haptenated, we also observed the haptenation of low abundant proteins by all 3 of the chemical sensitizers tested, indicating that within a complex protein background, protein abundance is not the sole determinant driving haptenation, highlighting a relationship to tertiary protein structure and the amino acid specificity of these chemical sensitizers and sensitizer potency.

Mitochondrial VDAC1: A Key Gatekeeper as Potential Therapeutic Target

Mitochondria are the key source of ATP that fuels cellular functions, and they are also central in cellular signaling, cell division and apoptosis. Dysfunction of mitochondria has been implicated in a wide range of diseases, including neurodegenerative and cardiac diseases, and various types of cancer. One of the key proteins that regulate mitochondrial function is the voltage-dependent anion channel 1 (VDAC1), the most abundant protein on the outer membrane of mitochondria. VDAC1 is the gatekeeper for the passages of metabolites, nucleotides, and ions; it plays a crucial role in regulating apoptosis due to its interaction with apoptotic and anti-apoptotic proteins, namely members of the Bcl-2 family of proteins and hexokinase. Therefore, regulation of VDAC1 is crucial not only for metabolic functions of mitochondria, but also for cell survival. In fact, multiple lines of evidence have confirmed the involvement of VDAC1 in several diseases. Consequently, modulation or dysregulation of VDAC1 function can potentially attenuate or exacerbate pathophysiological conditions. Understanding the role of VDAC1 in health and disease could lead to selective protection of cells in different tissues and diverse diseases. The purpose of this review is to discuss the role of VDAC1 in the pathogenesis of diseases and as a potentially effective target for therapeutic management of various pathologies.

The Association of VDAC with Cell Viability of PC12 Model of Huntington's Disease

It is becoming increasingly apparent that mitochondria dysfunction plays an important role in the pathogenesis of Huntington’s disease (HD), but the underlying mechanism is still elusive. Thus, there is a still need for further studies concerning the upstream events in the mitochondria dysfunction that could contribute to cell death observed in HD. Taking into account the fundamental role of the voltage-dependent anion-selective channel (VDAC) in mitochondria functioning, it is reasonable to consider the channel as a crucial element in HD etiology. Therefore, we applied inducible PC12 cell model of HD to determine the relationship between the effect of expression of wild type and mutant huntingtin (Htt and mHtt, respectively) on cell survival and mitochondria functioning in intact cells under conditions of undergoing cell divisions. Because after 48 h of Htt and mHtt expression differences in mitochondria functioning co-occurred with differences in the cell viability, we decided to estimate the effect of Htt and mHtt expression lasted for 48 h on VDAC functioning. Therefore, we isolated VDAC from the cells and tested the preparations by black lipid membrane system. We observed that the expression of mHtt, but not Htt, resulted in changes of the open state conductance and voltage-dependence when compared to control cells cultured in the absence of the expression. Importantly, for all the VDAC preparations, we observed a dominant quantitative content of VDAC1, and the quantitative relationships between VDAC isoforms were not changed by Htt and mHtt expression. Thus, Htt and mHtt-mediated functional changes of VDAC, being predominantly VDAC1, which occur shortly after these protein appearances in cells, may result in differences concerning mitochondria functioning and viability of cells expressing Htt and mHtt. The assumption is important for better understanding of cytotoxicity as well as cytoprotection mechanisms of potential clinical application.

News about VDAC1 in Hypoxia

The voltage-dependent anion channel (VDAC) is the main interface between the cytosol and mitochondria of cells. It plays a crucial role in both mitochondrial metabolism and cell death. The main basic function of this channel is to mediate and gate the flux of small ions, metabolites, and adenosine triphosphate. Changes in its structure, and thus conformation, are expected to affect its activity and modulate the ability of cancer cells to expand. In this review, we describe a novel mechanism by which mitochondria of cells in hypoxia, a low level of oxygen, protects from apoptosis. In hypoxia, some mitochondria become enlarged due to hyperfusion. These mitochondria possess a truncated form of VDAC1 (VDAC1-ΔC), which is linked to the higher metabolic capacity and the greater resistance to cell death of hypoxic cells. However, not all of the VDAC1 protein is truncated, but the amount of the full-length form is diminished compared to the amount in normoxic cells. First, we describe how such a decrease effects cell proliferation, respiration, glycolysis, and other processes. Second, we report on a novel mitochondrial-endolysosomal crosstalk that leads to VDAC1 truncation. By pharmacological targeting of VDAC1-ΔC, the production of energy could be turned off and the sensitivity to cell death restored. This could counteract the favorable microenvironment that gives cancer cells a growth advantage and thereby disrupts the balance between life and death, which is controlled by VDAC1.

Acrolein-an α,β-Unsaturated Aldehyde: A Review of Oral Cavity Exposure and Oral Pathology Effects

Acrolein is a highly reactive unsaturated aldehyde widely present in the environment, particularly as a product of tobacco smoke. Our previous studies indicated the adverse consequences of even short-term acrolein exposure and proposed a molecular mechanism of its potential harmful effect on oral cavity keratinocytic cells. In this paper we chose to review the broad spectrum of acrolein sources such as pollution, food, and smoking. Consequently, in this paper we consider a high level of oral exposure to acrolein through these sources and discuss the noxious effects it has on the oral cavity including on salivary quality and contents, oral resistance to oxidative stress, and stress mechanism activation in a variety of oral cells.

Tropomyosins in the healthy and diseased nervous system

Regulation of the actin cytoskeleton is dependent on a plethora of actin-associated proteins in all eukaryotic cells. The family of tropomyosins plays a key role in controlling the function of several of these actin-associated proteins and their access to actin filaments. In order to understand the regulation of the actin cytoskeleton in highly dynamic subcellular compartments of neurons such as growth cones of developing neurons and the synaptic compartment of mature neurons, it is pivotal to decipher the functional role of tropomyosins in the nervous system. In this review, we will discuss the current understanding and recent findings on the regulation of the actin cytoskeleton by tropomyosins and potential implication that this has for the dysregulation of the actin cytoskeleton in neurological diseases.

Modulation of learning and memory by natural polyamines

Spermine and spermidine are natural polyamines that are produced mainly via decarboxylation of l-ornithine and the sequential transfer of aminopropyl groups from S-adenosylmethionine to putrescine by spermidine synthase and spermine synthase. Spermine and spermidine interact with intracellular and extracellular acidic residues of different nature, including nucleic acids, phospholipids, acidic proteins, carboxyl- and sulfate-containing polysaccharides. Therefore, multiple actions have been suggested for these polycations, including modulation of the activity of ionic channels, protein synthesis, protein kinases, and cell proliferation/death, within others. In this review we summarize these neurochemical/neurophysiological/morphological findings, particularly those that have been implicated in the improving and deleterious effects of spermine and spermidine on learning and memory of naïve animals in shock-motivated and nonshock-motivated tasks, from a historical perspective. The interaction with the opioid system, the facilitation and disruption of morphine-induced reward and the effect of polyamines and putative polyamine antagonists on animal models of cognitive diseases, such as Alzheimer's, Huntington, acute neuroinflammation and brain trauma are also reviewed and discussed. The increased production of polyamines in Alzheimer's disease and the biphasic nature of the effects of polyamines on memory and on the NMDA receptor are also considered. In light of the current literature on polyamines, which include the description of an inborn error of the metabolism characterized by mild-to moderate mental retardation and polyamine metabolism alterations in suicide completers, we can anticipate that polyamine targets may be important for the development of novel strategies and approaches for understanding the etiopathogenesis of important central disorders and their pharmacological treatment.

Markov chain Monte Carlo based analysis of post-translationally modified VDAC gating kinetics

The voltage-dependent anion channel (VDAC) is the main conduit for permeation of solutes (including nucleotides and metabolites) of up to 5 kDa across the mitochondrial outer membrane (MOM). Recent studies suggest that VDAC activity is regulated via post-translational modifications (PTMs). Yet the nature and effect of these modifications is not understood. Herein, single channel currents of wild-type, nitrosated, and phosphorylated VDAC are analyzed using a generalized continuous-time Markov chain Monte Carlo (MCMC) method. This developed method describes three distinct conducting states (open, half-open, and closed) of VDAC activity. Lipid bilayer experiments are also performed to record single VDAC activity under un-phosphorylated and phosphorylated conditions, and are analyzed using the developed stochastic search method. Experimental data show significant alteration in VDAC gating kinetics and conductance as a result of PTMs. The effect of PTMs on VDAC kinetics is captured in the parameters associated with the identified Markov model. Stationary distributions of the Markov model suggest that nitrosation of VDAC not only decreased its conductance but also significantly locked VDAC in a closed state. On the other hand, stationary distributions of the model associated with un-phosphorylated and phosphorylated VDAC suggest a reversal in channel conformation from relatively closed state to an open state. Model analyses of the nitrosated data suggest that faster reaction of nitric oxide with Cys-127 thiol group might be responsible for the biphasic effect of nitric oxide on basal VDAC conductance.

TPM3 and TPM4 gene products segregate to the postsynaptic region of central nervous system synapses

Synaptic function in the central nervous system (CNS) is highly dependent on a dynamic actin cytoskeleton in both the pre- and the postsynaptic compartment. Remodelling of the actin cytoskeleton is controlled by tropomyosins, a family of actin-associated proteins which define distinct actin filament populations. Here we show that TPM3 and TPM4 gene products localize to the postsynaptic region in mouse hippocampal neurons. Furthermore our data confirm previous findings of isoform segregation to the pre- and postsynaptic compartments at CNS synapses. These data provide fundamental insights in the formation of functionally distinct actin filament populations at the pre- and post-synapse.

Aldehydes participation in oxidative stress in rat thymocytes in vitro

A variety of lipid radicals are formed under oxidative stress development. The further oxidation of these radicals leads to formation of numerous aldehydes. They can form postsynthetic modifications in proteins and nucleic acids that disrupt their functions. In the present study aldehydes role in the formation of oxidative stress parameters in rat thymocytes was investigated. Two models were used: iron-stimulated oxidative stress and exogenous aldehydes exposure to thymocytes. For oxidative stress induction, thymocytes (2 x 10(6) cells/ml HBSS, pH 7.2) were exposed to different concentrations of FeSO4 (20, 30, 40 microM) and ascorbic acid (100 microM) for 6 h. It resulted in increase of levels of aldehydes 29 times (90 +/- 6 nmol/10(7) cells), these changes led to increase of TBARS levels 4.4 times; the levels of protein CO groups 10 times, cell mitochondrial activity and low-molecular weight SH groups were decreased 1.5 and 2.3 times, respectively. Treatment with aldehydes acceptor dimedone (200 microM) significantly decreased the levels of aldehydes 3.7 times, TBARS 1.6 times and protein CO groups 5 times. It was shown that the levels of cell mitochondrial activity increase 1.4 times and the levels of SH groups 1.8 times. To compare the effects of aldehydes in induction of oxidative stress, thymocytes (2 x 10(6) cells/ml HBSS, pH 7.2) were exposed to 50-600 microM formaldehyde (FA), 50-600 microM glyoxal (GL), 50-600 microM methylglyoxal (MGL), 1-15 microM acrolein (ACR) for 6 h. TBARS levels were increased for FA 1.3 times and for other aldehydes about 5-7 times. The levels of protein CO groups were increase for FA 3.7 times, for MGL 7 times, for GL 13 times, for ACR 22 times. Levels of SH groups were decreased for FA 1.5 times, for MGL 2.6 times, for GL 3 times, for ACR 9 times. A decrease of cell mitochondrial activity 1.5 times observe for all aldehydes. Obtained results prove the aldehydes participation in the formation of oxidative stress parameters and their capability to oxidative stress induction in the rat thymocytes.

Mitochondrial ATP-dependent proteases in protection against accumulation of carbonylated proteins

Carbonylation is an irreversible oxidative modification of proteins induced by reactive oxygen species (ROS) and reactive nitrogen species (RNS) or by-products of oxidative stress. Carbonylation leads to the loss of protein function and is used as a marker of oxidative stress. Recent data indicate that carbonylation is not only an unfavorable chance process but may also play a significant role in the control of diverse physiological processes. In plants, carbonylated proteins have been found in all cellular compartments; however, mitochondria, one of the major sources of reactive species, show the highest levels of oxidatively modified proteins under normal or stress conditions. Carbonylated proteins tend to misfold and have to be removed to prevent the formation of harmful insoluble aggregates. Mitochondria have developed several pathways that continuously monitor and remove oxidatively damaged polypeptides, and the mitochondrial protein quality control (mtPQC) system, comprising chaperones and ATP-dependent proteases, is the first line of defense. The Lon protease has been recognized as a key protease involved in the removal of oxidized proteins in yeast and mammalian mitochondria, but not in plants. Recently, it has been reported that the inner-membrane human i-AAA and m-AAA and Arabidopsis i-AAA proteases are crucial components of the defense against accumulation of carbonylated proteins, but the molecular basis of their action is not yet clear. Altogether, the mitochondrial AAA proteases secure the mitochondrial proteome against accumulation of carbonylated proteins.

Proteomic analysis of rat cerebral cortex following subchronic acrolein toxicity

Acrolein, a member of reactive α,β-unsaturated aldehydes, is a major environmental pollutant. Acrolein is also produced endogenously as a toxic by-product of lipid peroxidation. Because of high reactivity, acrolein may mediate oxidative damages to cells and tissues. It has been shown to be involved in a wide variety of pathological states including pulmonary, atherosclerosis and neurodegenerative diseases. In this study we employed proteomics approach to investigate the effects of subchronic oral exposures to 3mg/kg of acrolein on protein expression profile in the brain of rats. Moreover effects of acrolein on malondialdehyde (MDA) levels and reduced glutathione (GSH) content were investigated. Our results revealed that treatment with acrolein changed levels of several proteins in diverse physiological process including energy metabolism, cell communication and transport, response to stimulus and metabolic process. Interestingly, several differentially over-expressed proteins, including β-synuclein, enolase and calcineurin, are known to be associated with human neurodegenerative diseases. Changes in the levels of some proteins were confirmed by Western blot. Moreover, acrolein increases the level of MDA, as a lipid peroxidation biomarker and decreased GSH concentrations, as a non-enzyme antioxidant in the brain of acrolein treated rats. These findings suggested that acrolein induces the oxidative stress and lipid peroxidation in the brain, and so that may contribute to the pathophysiology of neurological disorders.

Oxidative modification of lipoic acid by HNE in Alzheimer disease brain

Alzheimer disease (AD) is an age-related neurodegenerative disease characterized by the presence of three pathological hallmarks: synapse loss, extracellular senile plaques (SP) and intracellular neurofibrillary tangles (NFTs). The major component of SP is amyloid β-peptide (Aβ), which has been shown to induce oxidative stress. The AD brain shows increased levels of lipid peroxidation products, including 4-hydroxy-2-nonenal (HNE). HNE can react covalently with Cys, His, or Lys residues on proteins, altering structure and function of the latter. In the present study we measured the levels of the HNE-modified lipoic acid in brain of subjects with AD and age-matched controls. Lipoic acid is a key co-factor for a number of proteins including pyruvate dehydrogenase and α-ketoglutarate dehydrogenase, key complexes for cellular energetics. We observed a significant decrease in the levels of HNE-lipoic acid in the AD brain compared to that of age-matched controls. To investigate this phenomenon further, the levels and activity of lipoamide dehydrogenase (LADH) were measured in AD and control brains. Additionally, LADH activities were measured after in-vitro HNE-treatment to mice brains. Both LADH levels and activities were found to be significantly reduced in AD brain compared to age-matched control. HNE-treatment also reduced the LADH activity in mice brain. These data are consistent with a two-hit hypothesis of AD: oxidative stress leads to lipid peroxidation that, in turn, causes oxidative dysfunction of key energy-related complexes in mitochondria, triggering neurodegeneration. This study is consonant with the notion that lipoic acid supplementation could be a potential treatment for the observed loss of cellular energetics in AD and potentiate the antioxidant defense system to prevent or delay the oxidative stress in and progression of this devastating dementing disorder.

VDAC1: from structure to cancer therapy

Here, we review current evidence pointing to the function of VDAC1 in cell life and death, and highlight these functions in relation to cancer. Found at the outer mitochondrial membrane, VDAC1 assumes a crucial position in the cell, controlling the metabolic cross-talk between mitochondria and the rest of the cell. Moreover, its location at the boundary between the mitochondria and the cytosol enables VDAC1 to interact with proteins that mediate and regulate the integration of mitochondrial functions with other cellular activities. As a metabolite transporter, VDAC1 contributes to the metabolic phenotype of cancer cells. This is reflected by VDAC1 over-expression in many cancer types, and by inhibition of tumor development upon silencing VDAC1 expression. Along with regulating cellular energy production and metabolism, VDAC1 is also a key protein in mitochondria-mediated apoptosis, participating in the release of apoptotic proteins and interacting with anti-apoptotic proteins. The involvement of VDAC1 in the release of apoptotic proteins located in the inter-membranal space is discussed, as is VDAC1 oligomerization as an important step in apoptosis induction. VDAC also serves as an anchor point for mitochondria-interacting proteins, some of which are also highly expressed in many cancers, such as hexokinase (HK), Bcl2, and Bcl-xL. By binding to VDAC, HK provides both metabolic benefit and apoptosis-suppressive capacity that offers the cell a proliferative advantage and increases its resistance to chemotherapy. VDAC1-based peptides that bind specifically to HK, Bcl2, or Bcl-xL abolished the cell’s abilities to bypass the apoptotic pathway. Moreover, these peptides promote cell death in a panel of genetically characterized cell lines derived from different human cancers. These and other functions point to VDAC1 as a rational target for the development of a new generation of therapeutics.

Functional diversity of actin cytoskeleton in neurons and its regulation by tropomyosin

Neurons comprise functionally, molecularly, and spatially distinct subcellular compartments which include the soma, dendrites, axon, branches, dendritic spines, and growth cones. In this chapter, we detail the remarkable ability of the neuronal cytoskeleton to exquisitely regulate all these cytoplasmic distinct partitions, with particular emphasis on the microfilament system and its plethora of associated proteins. Importance will be given to the family of actin-associated proteins, tropomyosin, in defining distinct actin filament populations. The ability of tropomyosin isoforms to regulate the access of actin-binding proteins to the filaments is believed to define the structural diversity and dynamics of actin filaments and ultimately be responsible for the functional outcome of these filaments.

Proteomic profiling of acrolein adducts in human lung epithelial cells

Acrolein (2,3-propenal) is a major indoor and outdoor air pollutant originating largely from tobacco smoke or organic combustion. Given its high reactivity, the adverse effects of inhaled acrolein are likely due to direct interactions with the airway epithelium, resulting in altered epithelial function, but only limited information exists to date regarding the primary direct cellular targets for acrolein. Here, we describe a global proteomics approach to characterize the spectrum of airway epithelial protein targets for Michael adduction in acrolein-exposed bronchial epithelial (HBE1) cells, based on biotin hydrazide labeling and avidin purification of biotinylated proteins or peptides for analysis by LC-MS/MS. Identified protein targets included a number of stress proteins, cytoskeletal proteins, and several key proteins involved in redox signaling, including thioredoxin reductase, thioredoxin, peroxiredoxins, and glutathione S-transferase π. Because of the central role of thioredoxin reductase in cellular redox regulation, additional LC-MS/MS characterization was performed on purified mitochondrial thioredoxin reductase to identify the specific site of acrolein adduction, revealing the catalytic selenocysteine residue as the target responsible for enzyme inactivation. Our findings indicate that these approaches are useful in characterizing major protein targets for acrolein, and will enhance mechanistic understanding of the impact of acrolein on cell biology.

VDAC isoforms in mammals

VDACs (Voltage Dependent Anion selective Channels) are a family of pore-forming proteins discovered in the mitochondrial outer membrane. In the animal kingdom, mammals show a conserved genetic organization of the VDAC genes, corresponding to a group of three active genes. Three VDAC protein isoforms thus exist. From a historically point of view most of the data collected about this protein refer to the VDAC1 isoform, the first to be identified and also the most abundant in the organisms. In this work we compare the information available about the three VDAC isoforms, with a special emphasis upon the human proteins, here considered prototypical of the group, and we try to shed some light on specific functional roles of this apparently redundant group of proteins. A new hypothesis about the VDAC(s) involvement in ROS control is proposed. This article is part of a Special Issue entitled: VDAC structure, function, and regulation of mitochondrial metabolism.

Protein modification by acrolein: relevance to pathological conditions and inhibition by aldehyde sequestering agents

Acrolein (ACR) is a toxic and highly reactive α,β-unsaturated aldehyde widely distributed in the environment as a common pollutant and generated endogenously mainly by lipoxidation reactions. Its biological effects are due to its ability to react with the nucleophilic sites of proteins, to form covalently modified biomolecules which are thought to be involved as pathogenic factors in the onset and progression of many pathological conditions such as cardiovascular and neurodegenerative diseases. Functional impairment of structural proteins and enzymes by covalent modification (crosslinking) and triggering of key cell signalling systems are now well-recognized signs of cell and tissue damage induced by reactive carbonyl species (RCS). In this review, we mainly focus on the in vitro and in vivo evidence demonstrating the ability of ACR to covalently modify protein structures, in order to gain a deeper insight into the dysregulation of cellular and metabolic pathways caused by such modifications. In addition, by considering RCS and RCS-modified proteins as drug targets, this survey will provide an overview on the newly developed molecules specifically tested for direct or indirect ACR scavenging, and the more significant studies performed in the last years attesting the efficacy of compounds already recognized as promising aldehyde-sequestering agents.

Proteomic profiling of acrolein adducts in human lung epithelial cells

Acrolein (2,3-propenal) is a major indoor and outdoor air pollutant originating largely from tobacco smoke or organic combustion. Given its high reactivity, the adverse effects of inhaled acrolein are likely due to direct interactions with the airway epithelium, resulting in altered epithelial function, but only limited information exists to date regarding the primary direct cellular targets for acrolein. Here, we describe a global proteomics approach to characterize the spectrum of airway epithelial protein targets for Michael adduction in acrolein-exposed bronchial epithelial (HBE1) cells, based on biotin hydrazide labeling and avidin purification of biotinylated proteins or peptides for analysis by LC-MS/MS. Identified protein targets included a number of stress proteins, cytoskeletal proteins, and several key proteins involved in redox signaling, including thioredoxin reductase, thioredoxin, peroxiredoxins, and glutathione S-transferase π. Because of the central role of thioredoxin reductase in cellular redox regulation, additional LC-MS/MS characterization was performed on purified mitochondrial thioredoxin reductase to identify the specific site of acrolein adduction, revealing the catalytic selenocysteine residue as the target responsible for enzyme inactivation. Our findings indicate that these approaches are useful in characterizing major protein targets for acrolein, and will enhance mechanistic understanding of the impact of acrolein on cell biology.

Proteomic research in psychiatry

Psychiatric disorders such as Alzheimer's disease, schizophrenia and mood disorders are severe and disabling conditions of largely unknown origin and poorly understood pathophysiology. An accurate diagnosis and treatment of these disorders is often complicated by their aetiological and clinical heterogeneity. In recent years proteomic technologies based on mass spectrometry have been increasingly used, especially in the search for diagnostic and prognostic biomarkers in neuropsychiatric disorders. Proteomics enable an automated high-throughput protein determination revealing expression levels, post-translational modifications and complex protein-interaction networks. In contrast to other methods such as molecular genetics, proteomics provide the opportunity to determine modifications at the protein level thereby possibly being more closely related to pathophysiological processes underlying the clinical phenomenology of specific psychiatric conditions. In this article we review the theoretical background of proteomics and its most commonly utilized techniques. Furthermore the current impact of proteomic research on diverse psychiatric diseases, such as Alzheimer's disease, schizophrenia, mood and anxiety disorders, drug abuse and autism, is discussed. Proteomic methods are expected to gain crucial significance in psychiatric research and neuropharmacology over the coming decade.

Synaptoproteomics of learned helpless rats involve energy metabolism and cellular remodeling pathways in depressive-like behavior and antidepressant response

Although depression is a severe and life-threatening psychiatric illness, its pathogenesis still is essentially unknown. Recent studies highlighted the influence of environmental stress factors on an individual's genetic predisposition to develop mood disorders. In the present study, we employed a well-validated stress-induced animal model of depression, Learned Helplessness paradigm, in rats. Learned helpless (LH) and non-learned helpless (NLH) rats were treated with nortriptyline, a tricyclic antidepressant. The resulting 4 groups (LH vs. NLH, treated vs. non-treated), were subjected to global analysis of protein expression, a powerful approach to gain insight into the molecular mechanisms underlying vulnerability to psychiatric disorders and the long-term action of drug treatments. Many of the biological targets of antidepressant drugs are localized at synapses. Thus, to reduce the complexity of the proteome analyzed and to enrich for less abundant synaptic proteins, purified nerve terminals (synaptosomes) from prefrontal/frontal cortex (P/FC) and hippocampus (HPC) of LH-NLH rats were used. Synaptosomes were purified by differential centrifugation on Percoll gradients and analyzed by two-dimensional polyacrylamide gel electrophoresis (2-DE). Protein spots differently regulated in the various comparisons were excised from gels and identified by mass spectrometry. Proteins involved in energy metabolism and cellular remodeling were primarily dysregulated, when LH and NLH rats were compared. Moreover, several proteins (aconitate hydratase, pyruvate dehydrogenase E1, dihydropyrimidinase-related protein-2 and stathmin) were found to be regulated in opposite directions by stress and drug treatment. These proteins could represent new molecular correlates of both vulnerability to stress and response to drugs, and putative targets for the development of novel drugs with antidepressant action. This article is part of a Special Issue entitled 'Trends in neuropharmacology: in memory of Erminio Costa'.

Chemical probes for analysis of carbonylated proteins: a review

Protein carbonylation is a major form of protein oxidation and is widely used as an indicator of oxidative stress. Carbonyl groups do not have distinguishing UV or visible, spectrophotometric absorbance/fluorescence characteristics and thus their detection and quantification can only be achieved using specific chemical probes. In this paper, we review the advantages and disadvantages of several chemical probes that have been and are still being used for protein carbonyl analysis. These probes include 2,4-dinitrophenylhydazine (DNPH), tritiated sodium borohydride ([(3)H]NaBH(4)), biotin-containing probes, and fluorescence probes. As our discussions lean toward gel-based approaches, utilizations of these probes in 2D gel-based proteomic analysis of carbonylated proteins are illustrated where applicable. Analysis of carbonylated proteins by ELISA, immunofluorescent imaging, near infrared fluorescence detection, and gel-free proteomic approaches are also discussed where appropriate. Additionally, potential applications of blue native gel electrophoresis as a tool for first dimensional separation in 2D gel-based analysis of carbonylated proteins are discussed as well.

VDAC, a multi-functional mitochondrial protein regulating cell life and death

Research over the past decade has extended the prevailing view of the mitochondrion to include functions well beyond the generation of cellular energy. It is now recognized that mitochondria play a crucial role in cell signaling events, inter-organellar communication, aging, cell proliferation, diseases and cell death. Thus, mitochondria play a central role in the regulation of apoptosis (programmed cell death) and serve as the venue for cellular decisions leading to cell life or death. One of the mitochondrial proteins controlling cell life and death is the voltage-dependent anion channel (VDAC), also known as mitochondrial porin. VDAC, located in the mitochondrial outer membrane, functions as gatekeeper for the entry and exit of mitochondrial metabolites, thereby controlling cross-talk between mitochondria and the rest of the cell. VDAC is also a key player in mitochondria-mediated apoptosis. Thus, in addition to regulating the metabolic and energetic functions of mitochondria, VDAC appears to be a convergence point for a variety of cell survival and cell death signals mediated by its association with various ligands and proteins. In this article, we review what is known about the VDAC channel in terms of its structure, relevance to ATP rationing, Ca(2+) homeostasis, protection against oxidative stress, regulation of apoptosis, involvement in several diseases and its role in the action of different drugs. In light of our recent findings and the recently solved NMR- and crystallography-based 3D structures of VDAC1, the focus of this review will be on the central role of VDAC in cell life and death, addressing VDAC function in the regulation of mitochondria-mediated apoptosis with an emphasis on structure-function relations. Understanding structure-function relationships of VDAC is critical for deciphering how this channel can perform such a variety of functions, all important for cell life and death. This review also provides insight into the potential of VDAC1 as a rational target for new therapeutics.

Intermediate filament carbonylation during acute acrolein toxicity in A549 lung cells: functional consequences, chaperone redistribution, and protection by bisulfite

Extensive protein carbonylation accompanies cellular exposure to acrolein, a ubiquitous smoke constituent implicated in life-threatening pulmonary edema in fire victims, a condition involving rapid erosion of the "watertight" properties of respiratory epithelium. Since the identities of lung epithelial proteins that sustain carbonylation by acrolein are unknown, we sought to identify significant targets in subcellular fractions from A549 cells after 30 min exposure to either subtoxic or acutely toxic acrolein concentrations (60 or 360 fmol acrolein/cell). The lower concentration mainly modified cytosolic proteins while the higher concentration also damaged nuclear, membrane, and cytoskeletal proteins. The multifunctional intermediate filament proteins vimentin, keratin-18, keratin-7 and keratin-8, were conspicuous targets. Consistent with their mechanical functions, a loss of cellular adhesive strength accompanied adduction of the two most abundant intermediate filaments in A549 cells, keratins-8 and -18. Acrolein also elicited redistribution of several chaperones (Hsp40, -70, -90, and -110) to intermediate filament fractions, suggesting chaperone-mediated autophagy contributes to the triage of acrolein-adducted proteins. The carbonyl scavenger bisulfite suppressed acrolein toxicity, intermediate filament adduction, vimentin cross-linking, Hsp90 redistribution, and loss of cellular adhesive strength, while also suppressing vimentin hyperphosphorylation. These novel observations identify intermediate filaments as key targets for the reactive smoke constituent acrolein.

Toxicity of smoke extracts towards A549 lung cells: role of acrolein and suppression by carbonyl scavengers

The noxious 3-carbon electrophile acrolein forms on combustion of diverse organic matter including synthetic polymers such as polyethylene. While known to play a key role in smoke inhalation injury (SII), the molecular basis for the pulmonary toxicity of high dose acrolein-containing smoke is unclear. As a result, drug interventions in SII are poorly directed against pathogenetic smoke toxicants such as acrolein. The first aim of this study was to confirm a role for acrolein in the acute toxicity of smoke extracts towards A549 lung cells by monitoring adduction of known acrolein targets and the expression of acrolein-inducible genes. A second aim was to evaluate carbonyl scavengers for their abilities to protect cell targets and block smoke extract toxicity. Extracts were prepared by bubbling smoke released by smouldering polyethylene through a buffered saline-trap. Acrolein levels in the extracts were estimated via HPLC after derivatisation with 2,4-dinitrophenylhydrazine. Extracts were highly toxic towards A549 cells, eliciting greater ATP depletion than an equivalent concentration of acrolein alone. The toxicity was accompanied by pronounced carbonylation of several cytoskeletal targets, namely vimentin and keratins-7, -8 and -18. Western blotting revealed that polyethylene combustion products also upregulated several acrolein-responsive protein markers, including GADD45beta, NQO1, HMOX, Hsp70, Nur77 and Egr1. Several carbonyl scavengers (bisulfite, d-penicillamine, hydralazine and 1-hydrazinoisoquinoline) strongly attenuated smoke extract toxicity, with bisulfite suppressing both the adduction and cross-linking of intermediate filament targets. Bisulfite also suppressed the cytotoxicity of smoke extracts when detected using real-time monitoring of cellular impedance. These findings confirm a key role for acrolein in smoke cytotoxicity and suggest drugs that block acrolein toxicity deserve further investigation as possible interventions against SII.

Communication between mitochondria and nucleus: putative role for VDAC in reduction/oxidation mechanism

Voltage dependent anion channel (VDAC) was identified in 1976 and since that time has been extensively studied. It is well known that VDAC transports metabolites across the outer mitochondrial membrane. The simple transport function is indispensable for proper mitochondria functions and, consequently for cell activity, and makes VDAC crucial for a range of cellular processes including ATP rationing, Ca2+ homeostasis and apoptosis execution. Here, we review recent data obtained for Saccharomyces cerevisiae cells used as a model system concerning the putative role of VDAC in communication between mitochondria and the nucleus. The S. cerevisiae VDAC isoform known as VDAC1 (termed here YVDAC) mediates the cytosol reduction/oxidation (redox) state that contributes to regulation of expression and activity of cellular proteins including proteins that participate in protein import into mitochondria and antioxidant enzymes. Simultaneously, copper-and-zinc-containing superoxide dismutase (CuZnSOD) plays an important role in controlling YVDAC activity and expression levels. Thus, it is proposed that VDAC constitutes an important component of a regulatory mechanism based on the cytosol redox state.

Oxidatively modified proteins in Alzheimer's disease (AD), mild cognitive impairment and animal models of AD: role of Abeta in pathogenesis

Oxidative stress has been implicated in the pathogenesis of a number of diseases including Alzheimer's disease (AD). The oxidative stress hypothesis of AD pathogenesis, in part, is based on beta-amyloid peptide (Abeta)-induced oxidative stress in both in vitro and in vivo studies. Oxidative modification of the protein may induce structural changes in a protein that might lead to its functional impairment. A number of oxidatively modified brain proteins were identified using redox proteomics in AD, mild cognitive impairment (MCI) and Abeta models of AD, which support a role of Abeta in the alteration of a number of biochemical and cellular processes such as energy metabolism, protein degradation, synaptic function, neuritic growth, neurotransmission, cellular defense system, long term potentiation involved in formation of memory, etc. All the redox proteomics-identified brain proteins fit well with the appearance of the three histopathological hallmarks of AD, i.e., synapse loss, amyloid plaque formation and neurofibrillary tangle formation and suggest a direct or indirect association of the identified proteins with the pathological and/or biochemical alterations in AD. Further, Abeta models of AD strongly support the notion that oxidative stress induced by Abeta may be a driving force in AD pathogenesis. Studies conducted on arguably the earliest stage of AD, MCI, may elucidate the mechanism(s) leading to AD pathogenesis by identifying early markers of the disease, and to develop therapeutic strategies to slow or prevent the progression of AD. In this review, we summarized our findings of redox proteomics identified oxidatively modified proteins in AD, MCI and AD models.

Hop proanthocyanidins induce apoptosis, protein carbonylation, and cytoskeleton disorganization in human colorectal adenocarcinoma cells via reactive oxygen species

Proanthocyanidins (PCs) have been shown to suppress the growth of diverse human cancer cells and are considered as promising additions to the arsenal of chemopreventive phytochemicals. An oligomeric mixture of PCs from hops (Humulus lupulus) significantly decreased cell viability of human colon cancer HT-29 cells in a dose-dependent manner. Hop PCs, at 50 or 100 microg/ml, exhibited apoptosis-inducing properties as shown by the increase in caspase-3 activity. Increased levels of intracellular reactive oxygen species (ROS) was accompanied by an augmented accumulation of protein carbonyls. Mass spectrometry-based proteomic analysis in combination with 2-alkenal-specific immunochemical detection identified beta-actin and protein disulfide isomerase as major putative targets of acrolein adduction. Incubation of HT-29 cells with hop PCs resulted in morphological changes that indicated disruption of the actin cytoskeleton. PC-mediated hydrogen peroxide (H2O2) formation in the cell culture media was also quantified; but, the measured H2O2 levels would not explain the observed changes in the oxidative modifications of actin. These findings suggest new modes of action for proanthocyandins as anticarcinogenic agents in human colon cancer cells, namely, promotion of protein oxidative modifications and cytoskeleton derangement.

Proteomic profiling of rat lung epithelial cells induced by acrolein

AIMS

Acrolein is a highly toxic unsaturated aldehyde and is also an endogenous byproduct produced from lipid peroxidation. It can be formed from the breakdown of certain pollutants in outdoor air or from burning tobacco or gasoline. Inhalation and dermal exposure to acrolein are extremely toxic to human tissue. Although it is known that acrolein is toxic to lung tissue, no studies have attempted to address the changes induced by acrolein on a global scale.

MAIN METHODS

In the present study we have attempted to address the changes in global protein expression induced by acrolein using proteomics analysis in rat lung epithelial cells.

KEY FINDINGS

Our analysis reveals a comprehensive profiling of the proteins that includes a heterogeneous class of proteins and this compels one to consider that the toxic response to acrolein is very complex. There were 34 proteins that showed changes between the control cells and after acrolein treatment. The expression of 18 proteins was increased and the expression of 16 proteins was decreased following exposure to acrolein. We have further validated two differentially expressed proteins namely annexin II (ANXII) and prohibitin (PHB) in lung epithelial cells treated with acrolein.

SIGNIFICANCE

Based on the results of the overall proteomic analysis, acrolein appears to induce changes in a diverse range of proteins suggesting a complex mechanism of acrolein-induced toxicity in lung epithelial cells.

Proteomics-determined differences in the concanavalin-A-fractionated proteome of hippocampus and inferior parietal lobule in subjects with Alzheimer's disease and mild cognitive impairment: implications for progression of AD

Alzheimer's disease (AD) is the most common type of dementia, comprising 60-80% of all reported cases, and currently affects 5.2 million Americans. AD is characterized pathologically by the accumulation of senile plaques (SPs), neurofibrillary tangles (NFTs), and synapse loss. The early stages of memory loss associated with AD have been studied in a condition known as amnestic mild cognitive impairment (MCI), arguably the earliest form of AD. In spite of extensive research across a variety of disciplines, the cause of AD remains elusive. Proteomics techniques have helped to advance knowledge about AD by identifying irregularities in protein expression and post-translational modifications (PTMs) in AD brain. Glycosylation is a less studied PTM with regards to AD and MCI. This PTM is important to study because glycosylation is involved in proper protein folding, protein anchoring to cell membranes, and the delivery of proteins to organelles, and these processes are impaired in AD. Concanavalin-A (Con-A) binds to N-linked glycoproteins, but hydrophobic sites on nonglycoproteins are also known to bind Con-A. To our knowledge, the present study is the first to examine Con-A-associated brain proteins in MCI and AD with focus on the hippocampus and inferior parietal lobule (IPL) brain regions. Proteins found in AD hippocampus with altered levels are glutamate dehydrogenase (GDH), glial fibrillary acidic protein (GFAP), tropomyosin 3 (TPM3), Rab GDP-dissociation inhibitor XAP-4 (XAP4), and heat shock protein 90 (HSP90). Proteins found with altered levels in AD IPL are alpha-enolase, gamma-enolase, and XAP-4. MCI hippocampal proteins with altered levels are dihydropyrimidase-2 (DRP2), glucose-regulated protein 78 (GRP-78), protein phosphatase related protein Sds-22 (Sds22), and GFAP and the only protein found with altered levels in MCI IPL was beta-synuclein. These results are discussed with reference to biochemical and pathological alterations in and progression of AD.

Cu,Zn-superoxide dismutase is necessary for proper function of VDAC in Saccharomyces cerevisiae cells

Available data suggest that a copper-and zinc-containing dismutase (CuZnSOD) plays a significant role in protecting eukaryotic cells against oxidative modifications which may contribute to cell aging. Here we demonstrated that depletion of CuZnSOD in Saccharomyces cerevisiae cells (Deltasod1 cells) affected distinctly channel activity of VDAC (voltage dependent anion selective channel) and resulted in a moderate reduction in VDAC levels as well as in levels of protein crucial for VDAC import into mitochondria, namely Tob55/Sam50 and Tom40. The observed alterations may result in mitochondriopathy and subsequently in the shortening of the replicative life span observed for S. cerevisiaeDeltasod1 cells.

Protective effect of Pycnogenol in human neuroblastoma SH-SY5Y cells following acrolein-induced cytotoxicity

Oxidative stress is one of the hypotheses involved in the etiology of Alzheimer's disease (AD). Considerable attention has been focused on increasing the intracellular glutathione (GSH) levels in many neurodegenerative diseases, including AD. Pycnogenol (PYC) has antioxidant properties and stabilizes intracellular antioxidant defense systems including glutathione levels. The present study investigated the protective effects of PYC on acrolein-induced oxidative cell toxicity in cultured SH-SY5Y neuroblastoma cells. Decreased cell survival in SH-SY5Y cultures treated with acrolein correlated with oxidative stress, increased NADPH oxidase activity, free radical production, protein oxidation/nitration (protein carbonyl, 3-nitrotyrosine), and lipid peroxidation (4-hydroxy-2-nonenal). Pretreatment with PYC significantly attenuated acrolein-induced cytotoxicity, protein damage, lipid peroxidation, and cell death. A dose-response study suggested that PYC showed protective effects against acrolein toxicity by modulating oxidative stress and increasing GSH. These findings provide support that PYC may provide a promising approach for the treatment of oxidative stress-related neurodegenerative diseases such as AD.