Lipid Peroxidation and Tyrosine Nitration in Traumatic Brain Injury: Insights into Secondary Injury from Redox Proteomics

Traumatic brain injury (TBI) is a spontaneous event in which sudden trauma and secondary injury cause brain damage. Symptoms of TBI can range from mild to severe depending on extent of injury. The outcome can span from complete patient recovery to permanent memory loss and neurological decline. Currently, there is no known cure for TBI; however, immediate medical attention after injury is most beneficial for patient recovery. It is a well-established concept that imbalances in the production of reactive oxygen species (ROS), reactive nitrogen species (RNS), and native antioxidant mechicanisms have been shown to increase oxidative stress. Over the years, proteomics has been used to identify specific biomarkers in diseases such as cancers and neurological disorders such as Alzheimer disease and Parkinson disease. As TBI is a risk factor for a multitude of neurological diseases, biomarkers for this phenomenon are a likely field of study in order to confirm diagnosis. This review highlights the current proteomics studies that investigated excessively nitrated proteins and those altered by lipid peroxidation in TBI. This review also highlights possible diagnostic measures and provides insights for future treatment strategies

Redox Proteomics in Some Age-Related Neurodegenerative Disorders or Models Thereof

Neurodegenerative diseases cause memory loss and cognitive impairment. Results from basic and clinical scientific research suggest a complex network of mechanisms involved in the process of neurodegeneration. Progress in treatment of such disorders requires researchers to better understand the functions of proteins involved in neurodegenerative diseases, to characterize their role in pathogenic disease mechanisms, and to explore their roles in the diagnosis, treatment, and prevention of neurodegenerative diseases. A variety of conditions of neurodegenerative diseases often lead to post-translational modifications of proteins, including oxidation and nitration, which might be involved in the pathogenesis of neurodegenerative diseases. Redox proteomics, a subset of proteomics, has made possible the identification of specifically oxidized proteins in neurodegenerative disorders, providing insight into a multitude of pathways that govern behavior and cognition and the response of the nervous system to injury and disease. Proteomic analyses are particularly suitable to elucidate post-translational modifications, expression levels, and protein-protein interactions of thousands of proteins at a time. Complementing the valuable information generated through the integrative knowledge of protein expression and function should enable the development of more efficient diagnostic tools and therapeutic modalities. Here we review redox proteomic studies of some neurodegenerative diseases

Role of ROS and RNS Sources in Physiological and Pathological Conditions

There is significant evidence that, in living systems, free radicals and other reactive oxygen and nitrogen species play a double role, because they can cause oxidative damage and tissue dysfunction and serve as molecular signals activating stress responses that are beneficial to the organism. Mitochondria have been thought to both play a major role in tissue oxidative damage and dysfunction and provide protection against excessive tissue dysfunction through several mechanisms, including stimulation of opening of permeability transition pores. Until recently, the functional significance of ROS sources different from mitochondria has received lesser attention. However, the most recent data, besides confirming the mitochondrial role in tissue oxidative stress and protection, show interplay between mitochondria and other ROS cellular sources, so that activation of one can lead to activation of other sources. Thus, it is currently accepted that in various conditions all cellular sources of ROS provide significant contribution to processes that oxidatively damage tissues and assure their survival, through mechanisms such as autophagy and apoptosis

Roles of amyloid β-peptide-associated oxidative stress and brain protein modifications in the pathogenesis of Alzheimer\u27s disease and mild cognitive impairment

Oxidative stress has been implicated to play a crucial role in the pathogenesis of a number of diseases, including neurodegenerative disorders, cancer, and ischemia, just to name a few. Alzheimer disease (AD) is an age-related neurodegenerative disorder that is recognized as the most common form of dementia. AD is histopathologically characterized by the presence of extracellular amyloid plaques, intracellular neurofibrillary tangles, the presence of oligomers of amyloid β-peptide (Aβ), and synapse loss. In this review we discuss the role of Aβ in the pathogenesis of AD and also the use of redox proteomics to identify oxidatively modified brain proteins in AD and mild cognitive impairment. In addition, redox proteomics studies in in vivo models of AD centered around Aβ(1-42) are discussed

Proteomic identification of HNE-bound proteins in early Alzheimer disease: Insights into the role of lipid peroxidation in the progression of AD

Early Alzheimer\u27s disease (EAD) is the intermediary stage between mild cognitive impairment (MCI) and late-stage Alzheimer\u27s disease (AD). The symptoms of EAD mirror the disease advancement between the two phases. Dementia, memory deficits, and cognitive decline are more pronounced as the disease progresses. Oxidative stress in brain is reported in MCI and AD, including lipid peroxidation indexed by protein-bound 4-hydroxy-2-nonenal (HNE). There are limited data regarding the proteomics analysis of brain from subjects with EAD and even less concerning the possible relationship of EAD HNE-modified brain proteins with HNE-modified proteins in MCI and AD. Proteomics was utilized to investigate excessively HNE-bound brain proteins in EAD compared to those in control. These new results provide potentially valuable insight into connecting HNE-bound brain proteins in EAD to those previously identified in MCI and AD, since EAD is a transitional stage between MCI and late-stage AD. In total, six proteins were found to be excessively covalently bound by HNE in EAD inferior parietal lobule (IPL) compared to age-related control brain. These proteins play roles in antioxidant defense (manganese superoxide dismutase), neuronal communication and neurite outgrowth (dihydropyriminidase-related protein 2), and energy metabolism (alpha-enolase, malate dehydrogenase, triosephosphate isomerase, and F1 ATPase, alpha subunit). This study shows that there is an overlap of brain proteins in EAD with previously identified oxidatively modified proteins in MCI and late-stage AD. The results are consistent with the hypothesis that oxidative stress, in particular lipid peroxidation, is an early event in the progression of AD, and is the first to identify in EAD identical brain proteins previously identified as HNE-modified in MCI and late-state AD

Proteomic identification of nitrated brain proteins in traumatic brain-injured rats treated postinjury with gamma-glutamylcysteine ethyl ester: insights into the role of elevation of glutathione as a potential therapeutic strategy for traumatic brain injury

Traumatic brain injury (TBI) occurs suddenly and has damaging effects to the brain that are dependent on the severity of insult. Symptoms can be mild, moderate, or severe. Oxidative damage is associated with traumatic brain injury through reactive oxygen/nitrogen species production. One such species, peroxynitrite, is elevated in TBI brain tissue (Orihara et al. [2001] Forensic Sci. Int. 123:142-149; Deng et al. [2007] Exp. Neurol. 205:154-165). Peroxynitrite can react with carbon dioxide and decompose to produce NO(2) and carbonate radicals, which in turn can lead to 3-nitrotyrosine, an index of protein nitration. Gamma-glutamylcysteine ethyl ester (GCEE) is an ethyl ester moiety of gamma-glutamylcysteine, an agent that up-regulates glutathione (GSH) production in brain (Drake et al. [2002] J. Neurosci. Res. 68:776-784). Many preclinical studies of TBI have employed pretreatment of animals with proposed beneficial agents prior to the injury itself. However, in the real world of TBI, treatment begins postinjury. Hence, insights into agents that improve outcome following injury are desperately needed. This study is one of the first to investigate a potential GSH-based therapy for TBI postinjury. Protein carbonyls, an index of protein oxidation, were significantly elevated in brain of animals subjected to TBI. However, if, after TBI, GCEE was administered i.p., protein carbonyl levels were significantly reduced. Similarly, 3-nitrotyrosine levels were elevated in brain following TBI but significantly decreased following TBI if GCEE was administered i.p. Redox proteomics analysis showed that several brain proteins were nitrated after TBI. However, if GCEE was given i.p. following TBI, many of these proteins were protected from nitration. The results are encouraging and are discussed with reference to potential therapeutic strategies for TBI involving elevated GSH

Role of Phenylalanine 20 in Alzheimer\u27s Amyloid β-peptide (1-42)-induced Oxidative Stress and Neurotoxicity

Senile plaques are a hallmark of Alzheimer\u27s disesae (AD), a neurodegenerative disease associated with cognitive decline and aging. Aβ(1-42) is the primary component of the senile plaque in AD brain and has been shown to induce protein oxidation in vitro and in vivo. Oxidative stress is extensive in AD brain. As a result, Aβ(1-42) has been proposed to play a central role in the pathogenesis of AD; however, the specific mechanism of neurotoxicity remains unknown. Recently, it has been proposed that long distance electron transfer from methionine 35 to the Cu(II) bound at the N terminus of Aβ(1-42) occurs via phenylalanine 20. Additionally, it was proposed that substitution of phenylalanine 20 of Aβ(1-42) by alanine [Aβ(1-42)F20A] would lessen the neurotoxicity induced by Aβ(1-42). In this study, we evaluate the predictions of this theoretical study by determining the oxidative stress and neurotoxic properties of Aβ(1-42)F20A relative to Aβ(1-42) in primary neuronal cell culture. Aβ(1-42)F20A induced protein oxidation and lipid peroxidation similar to Aβ(1-42) but to a lesser extent and in a manner inhibited by pretreatment of neurons with vitamin E. Additionally, Aβ(1-42)F20A affected mitochrondrial function similar to Aβ(1-42), albeit to a lesser extent. Furthermore, the mutation does not appear to abolish the ability of the native peptide to reduce Cu(II). Aβ(1-42)F20A did not compromise neuronal morphology at 24 h incubation with neurons, but did so after 48 h incubation. Taken together, these results suggest that long distance electron transfer from methionine 35 through phenylalanine 20 may not play a pivotal role in Aβ(1-42)-mediated oxidative stress and neurotoxicity

Proteomic identification of nitrated brain proteins in early Alzheimer\u27s disease inferior parietal lobule

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by progressive decline in multiple cognitive domains. Its pathological hallmarks include senile plaques and neurofibrillary tangles. Mild cognitive impairment (MCI) is the earliest detectable stage of AD with limited symptomology and no dementia. The yearly conversion rate of patients from MCI to AD is 10–15%, although conversion back to normal is possible in a small percentage. Early diagnosis of AD is important in an attempt to intervene or slow the advancement of the disease. Early AD (EAD) is a stage following MCI and characterized by full-blown dementia; however, information involving EAD is limited. Oxidative stress is well-established in MCI and AD, including protein oxidation. Protein nitration also is an important oxidative modification observed in MCI and AD, and proteomic analysis from our laboratory identified nitrated proteins in both MCI and AD. Therefore, in the current study, a proteomics approach was used to identify nitrated brain proteins in the inferior parietal lobule from four subjects with EAD. Eight proteins were found to be significantly nitrated in EAD: peroxiredoxin 2, triose phosphate isomerase, glutamate dehydrogenase, neuropolypeptide h3, phosphoglycerate mutase1, H+– transporting ATPase, α-enolase and fructose-1,6-bisphosphate aldolase. Many of these proteins are also nitrated in MCI and late-stage AD, making this study the first to our knowledge to link nitrated proteins in all stages of AD. These results are discussed in terms of potential involvement in the progression of this dementing disorder