4-hydroxy-2-nonenal and Down-Syndrome

Down syndrome (DS), trisomy of chromosome 21, is the most common genetic form of intellectual disability. The neuropathology of DS involves multiple molecular mechanisms, similar to AD, including the deposition of beta-amyloid (Aβ) into senile plaques and tau hyperphosphorylationg in neurofibrillary tangles. Interestingly, many genes encoded by chromosome 21, in addition to being primarily linked to amyloid-beta peptide (Aβ) pathology, are responsible for increased oxidative stress (OS) conditions that also result as a consequence of reduced antioxidant system efficiency. However, redox homeostasis is disturbed by overproduction of Aβ, which accumulates into plaques across the lifespan in DS as well as in AD, thus generating a vicious cycle that amplifies OS-induced intracellular changes. The present review describes the current literature that demonstrates the accumulation of oxidative damage in DS with a focus on the lipid peroxidation by-product, 4-hydroxy-2-nonenal (HNE). HNE reacts with proteins and can irreversibly impair their functions. We suggest that among different post-translational modifications, HNE-adducts on proteins accumulate in DS brain and play a crucial role in causing the impairment of glucose metabolism, neuronal trafficking, protein quality control and antioxidant response. We hypothesize that dysfunction of these specific pathways contribute to accelerated neurodegeneration associated with AD neuropathology.

Topics: Aldehydes; Alzheimer Disease; Amyloid beta-Peptides; Down Syndrome; Glucose; Humans; Lipid Peroxidation; Mitochondria; Neurofibrillary Tangles; Neurons; Oxidative Stress; Plaque, Amyloid; Protein Processing, Post-Translational; tau Proteins

Down syndrome (DS) is the most common genetic cause of intellectual disability, due to partial or complete triplication of chromosome 21. DS subjects are characterized by a number of abnormalities including premature aging and development of Alzheimer disease (AD) neuropathology after approximately 40 years of age. Several studies show that oxidative stress plays a crucial role in the development of neurodegeneration in the DS population. Increased lipid peroxidation is one of the main events causing redox imbalance within cells through the formation of toxic aldehydes that easily react with DNA, lipids, and proteins. In this study we used a redox proteomics approach to identify specific targets of 4-hydroxynonenal modifications in the frontal cortex from DS cases with and without AD pathology. We suggest that a group of identified proteins followed a specific pattern of oxidation in DS vs young controls, probably indicating characteristic features of the DS phenotype; a second group of identified proteins showed increased oxidation in DS/AD vs DS, thus possibly playing a role in the development of AD. The third group of comparison, DS/AD vs old controls, identified proteins that may be considered specific markers of AD pathology. All the identified proteins are involved in important biological functions including intracellular quality control systems, cytoskeleton network, energy metabolism, and antioxidant response. Our results demonstrate that oxidative damage is an early event in DS, as well as dysfunctions of protein-degradation systems and cellular protective pathways, suggesting that DS subjects are more vulnerable to oxidative damage accumulation that might contribute to AD development. Further, considering that the majority of proteins have been already demonstrated to be oxidized in AD brain, our results strongly support similarities with AD in DS.

Topics: Adolescent; Adult; Aldehydes; Alzheimer Disease; Child; Disease Progression; Down Syndrome; Female; Frontal Lobe; Humans; Infant; Male; Middle Aged; Nerve Tissue Proteins; Oxidation-Reduction; Oxidative Stress; Protein Processing, Post-Translational; Proteolysis; Proteomics

Elevated oxidative stress has been suggested to be associated with the features of Down's syndrome (DS). We previously reported increased oxidative stress in cultured cells from the embryonic brain of Ts1Cje, a mouse genetic DS model. However, since in vivo evidence for increased oxidative stress is lacking, we here examined lipid peroxidation, a typical marker of oxidative stress, in the brains of Ts1Cje and another DS mouse model Ts2Cje with an overlapping but larger trisomic segment. Accumulations of proteins modified with the lipid peroxidation-derived products, 13-hydroperoxy-9Z,11E-octadecadienoic acid and 4-hydroxy-2-nonenal were markedly increased in Ts1Cje and Ts2Cje brains. Analysis with oxidation-sensitive fluorescent probe also showed that reactive oxygen species themselves were increased in Ts1Cje brain. However, electron spin resonance analysis of microdialysate from the hippocampus of Ts1Cje showed that antioxidant activity remained unaffected, suggesting that the reactive oxygen species production was accelerated in Ts1Cje. Proteomics approaches with mass spectrometry identified the proteins modified with 13-hydroperoxy-9Z,11E-octadecadienoic acid and/or 4-hydroxy-2-nonenal to be involved in either ATP generation, the neuronal cytoskeleton or antioxidant activity. Structural or functional impairments of these proteins by such modifications may contribute to the DS features such as cognitive impairment that are present in the Ts1Cje mouse.

Topics: Age Factors; Aldehydes; Animals; Brain; Disease Models, Animal; Down Syndrome; Electrophoresis, Gel, Two-Dimensional; Female; Gene Expression Regulation; Humans; Linoleic Acids; Lipid Peroxidation; Lipid Peroxides; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Microdialysis; Reactive Oxygen Species; Trisomy

Persons with Down syndrome have increased vulnerability to oxidative stress caused by overexpression of superoxide dismutase, an antioxidant enzyme coded on chromosome 21. Increased oxidative stress may lead to oxidative damage of important macromolecules. We monitored this damage by measuring levels of different biomarkers of oxidative stress (protein carbonyls and 4-hydroxy-2-nonenal), as well as plasma antioxidant capacity, in children with Down syndrome. A total of 20 children with Down syndrome and 18 healthy individuals were recruited for this purpose.. Plasma protein carbonyls were measured using an ELISA technique, 4-hydroxy-2-nonenal was monitored by HPLC and the antioxidant capacity was evaluated using a ferric reducing ability of plasma (FRAP) assay.. We found that children with Down syndrome had significantly elevated levels of protein carbonyls compared to healthy controls (p < 0.01). Levels of 4-hydroxy-2-nonenal and antioxidant capacity were similar in both groups.. Our results on oxidative damage to proteins confirm the assumption of increased oxidative stress in individuals with Down syndrome.

Topics: Aldehydes; Antioxidants; Biomarkers; Child; Child, Preschool; Down Syndrome; Enzyme-Linked Immunosorbent Assay; Humans; Oxidative Stress; Protein Carbonylation; Proteins; Superoxide Dismutase

In Down's syndrome, the presence of three copies of chromosome 21 is associated with premature aging and progressive mental retardation sharing the pathological features of Alzheimer disease. Early cortical dysgenesis and late neuronal degeneration are probably caused by an overproduction of amyloid beta-peptide, followed by an increased cellular oxidation. Interestingly, chromosome 21 codes for superoxide-dismutase and amyloid beta precursor resulting, in Down's syndrome, in an overflow of these gene products and metabolites. We studied Down's fetal brain cortex to evaluate the presence and amount of lipid and protein oxidation markers; moreover, we quantified two forms of glycation end products that are known to be involved in the process of cellular oxidation. All these parameters are significantly increased in Down's fetal brains in comparison to controls, providing the evidence that accelerated brain glycoxidation occurs very early in the life of Down's syndrome subjects.

Topics: Aldehydes; Amyloid beta-Protein Precursor; Arginine; Brain; Cerebral Cortex; Down Syndrome; Gestational Age; Glycation End Products, Advanced; Glycosylation; Humans; Lipid Peroxidation; Lysine; Norleucine; Oxidation-Reduction; Oxidative Stress; Pyrroles; Superoxide Dismutase; Thiobarbituric Acid Reactive Substances