Mutations in DJ-1 cause an autosomal recessive, early onset familial form of Parkinson disease (PD). However, little is presently known about the role of DJ-1 in the more common sporadic form of PD and in other age-related neurodegenerative diseases, such as Alzheimer disease (AD). Here we report that DJ-1 is oxidatively damaged in the brains of patients with idiopathic PD and AD. By using a combination of two-dimensional gel electrophoresis and mass spectrometry, we have identified 10 different DJ-1 isoforms, of which the acidic isoforms (pI 5.5 and 5.7) of DJ-1 monomer and the basic isoforms (pI 8.0 and 8.4) of SDS-resistant DJ-1 dimer are selectively accumulated in PD and AD frontal cortex tissues compared with age-matched controls. Quantitative Western blot analysis shows that the total level of DJ-1 protein is significantly increased in PD and AD brains. Mass spectrometry analyses reveal that DJ-1 is not only susceptible to cysteine oxidation but also to previously unsuspected methionine oxidation. Furthermore, we show that DJ-1 protein is irreversibly oxidized by carbonylation as well as by methionine oxidation to methionine sulfone in PD and AD. Our study provides new insights into the oxidative modifications of DJ-1 and indicates association of oxidative damage to DJ-1 with sporadic PD and AD.Alzheimer disease (AD) 2 and Parkinson disease (PD) are the two most common neurodegenerative disorders characterized by the selective loss of neurons in specific brain regions and the deposition of misfolded proteins into aggregates or inclusions, such as neurofibrillary tangles and amyloid plaques in AD and Lewy bodies in PD (1). The majority of AD and PD cases are sporadic with hereditary familial cases accounting for less than 10% (2, 3). The genetic defects underlying several monogenic familial forms of AD and PD have recently been identified (3). However, the causes of other AD and PD cases, particularly sporadic cases, remain unclear.Increasing evidence indicates that oxidative stress plays a crucial role in the pathogenesis of idiopathic AD and PD (4 -7). For example, both AD and PD have been associated with increased production of reactive oxygen species (ROS), which could result from a combination of aging, genetic predisposition, and environmental factors (6). Epidemiological studies suggest that exposure to pesticides, herbicides, and other environmental toxins that inhibit mitochondrial complex I can lead to excess production of ROS and increased incidence of sporadic PD (8). Furthermore, post-mortem analyses reveal that the overall levels of oxidative damage to proteins, lipids, and DNA are elevated in AD and PD brains (4, 9).The most widely used marker for oxidative damage to proteins is the presence of carbonyl groups, which can be introduced into proteins by direct oxidation of Pro, Arg, Lys, or Thr side chains or by Michael addition reactions of Cys, His, or Lys residues with products of lipid peroxidation or glycooxidation (5, 10, 11). Elevation in the total level of protein carbonyls has been doc...

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The transient receptor potential vanilloid 1 (TRPV1) channel is the principal detector of noxious heat in the peripheral nervous system. TRPV1 is expressed in many nociceptors and is involved in heat-induced hyperalgesia and thermoregulation. The precise mechanism or mechanisms mediating the thermal sensitivity of TRPV1 are unknown. Here, we have shown that the oxidized linoleic acid metabolites 9-and 13-hydroxyoctadecadienoic acid (9-and 13-HODE) are formed in mouse and rat skin biopsies by exposure to noxious heat. 9-and 13-HODE and their metabolites, 9-and 13-oxoODE, activated TRPV1 and therefore constitute a family of endogenous TRPV1 agonists. Moreover, blocking these substances substantially decreased the heat sensitivity of TRPV1 in rats and mice and reduced nociception. Collectively, our results indicate that HODEs contribute to the heat sensitivity of TRPV1 in rodents. Because oxidized linoleic acid metabolites are released during cell injury, these findings suggest a mechanism for integrating the hyperalgesic and proinflammatory roles of TRPV1 and linoleic acid metabolites and may provide the foundation for investigating new classes of analgesic drugs. IntroductionThe TRP family of ligand-gated ion channels consists of several subgroups, including the vanilloid subfamily (transient receptor potential vanilloid [TRPV]). The first member of the subfamily to be discovered, TRPV1, is an extensively studied channel (1-5) that is expressed in a substantial proportion of pain-sensing sensory neurons, termed nociceptors. TRPV1 can be activated by a variety of endogenous lipids (including lipoxygenase and phospholipase D metabolites of arachidonic acid) and by exogenous substances such as capsaicin (the pungent compound in hot chili peppers) (6). We recently discovered that linoleic acid metabolites are synthesized in the spinal dorsal horn following the afferent barrage due to stimuli such as peripheral inflammation and constitute what we believe to be a novel, physiologically active family of endogenous TRPV1 ligands that mediates central sensitization to mechanical stimuli (7).In the periphery, TRPV1 also serves as a detector for noxious heat (> 43°C) (6), and pharmacological and gene deletion studies have shown that TRPV1 is important in inflammatory heat hyperalgesia and thermoregulation (8-9). However, the precise mechanism of heat activation of TRPV1 remains unknown. We found that endogenous TRPV1 agonists are formed on exposure of cell membranes to noxious heat. The released compounds activate TRPV1 and contribute to the thermal responsiveness of this channel.

Although oxidative stress has been strongly implicated in the pathogenesis of Alzheimer disease (AD) and Parkinson disease (PD), the identities of specific protein targets of oxidative damage remain largely unknown. Here, we report that Cu,Zn-superoxide dismutase (SOD1), a key antioxidant enzyme whose mutations have been linked to autosomal dominant neurodegenerative disorder familial amyotrophic lateral sclerosis (ALS), is a major target of oxidative damage in AD and PD brains. By using a combination of twodimensional gel electrophoresis, immunoblot analysis, and mass spectrometry, we have identified four human brain SOD1 isoforms with pI values of 6.3, 6.0, 5.7, and 5.0, respectively. Of these, the SOD1 pI 6.0 isoform is oxidatively modified by carbonylation, and the pI 5.0 isoform is selectively accumulated in AD and PD. Moreover, Cys-146, a cysteine residue of SOD1 that is mutated in familial ALS, is oxidized to cysteic acid in AD and PD brains. Quantitative Western blot analyses demonstrate that the total level of SOD1 isoforms is significantly increased in both AD and PD. Furthermore, immunohistochemical and double fluorescence labeling studies reveal that SOD1 forms proteinaceous aggregates that are associated with amyloid senile plaques and neurofibrillary tangles in AD brains. These findings implicate, for the first time, the involvement of oxidative damage to SOD1 in the pathogenesis of sporadic AD and PD. This work suggests that AD, PD, and ALS may share a common or overlapping pathogenic mechanism(s) that could potentially be targeted by similar therapeutic strategies.

Isocitrate dehydrogenases (IDH) convert isocitrate to alpha-ketoglutarate (α-KG). In cancer, mutant IDH1/2 reduces α-KG to D2-hydroxyglutarate (D2-HG) disrupting α-KG-dependent dioxygenases. However, the physiological relevance of controlling the interconversion of D2-HG into α-KG, mediated by D2-hydroxyglutarate dehydrogenase (D2HGDH), remains obscure. Here we show that wild-type D2HGDH elevates α-KG levels, influencing histone and DNA methylation, and HIF1α hydroxylation. Conversely, the D2HGDH mutants that we find in diffuse large B-cell lymphoma are enzymatically inert. D2-HG is a low-abundance metabolite, but we show that it can meaningfully elevate α-KG levels by positively modulating mitochondrial IDH activity and inducing IDH2 expression. Accordingly, genetic depletion of IDH2 abrogates D2HGDH effects, whereas ectopic IDH2 rescues D2HGDH-deficient cells. Our data link D2HGDH to cancer and describe an additional function for the enzyme: the regulation of IDH2 activity and α-KG-mediated epigenetic remodeling. These data further expose the intricacies of mitochondrial metabolism and inform on the pathogenesis of D2HGDH-deficient diseases.