prostaglandin-d2 and Nerve-Degeneration

Cyclopentenone prostaglandins (CyPGs), such as 15-deoxy-Δ(12,14) -prostaglandin J(2) (15d-PGJ(2)), are active prostaglandin metabolites exerting a variety of biological effects that may be important in the pathogenesis of neurological diseases. Ubiquitin-C-terminal hydrolase L1 (UCH-L1) is a brain specific deubiquitinating enzyme whose aberrant function has been linked to neurodegenerative disorders. We report that [15d-PGJ(2)] detected by quadrapole mass spectrometry (MS) increases in rat brain after temporary focal ischemia, and that treatment with 15d-PGJ(2) induces accumulation of ubiquitinated proteins and exacerbates cell death in normoxic and hypoxic primary neurons. 15d-PGJ(2) covalently modifies UCH-L1 and inhibits its hydrolase activity. Pharmacologic inhibition of UCH-L1 exacerbates hypoxic neuronal death while transduction with a TAT-UCH-L1 fusion protein protects neurons from hypoxia. These studies indicate that UCH-L1 function is important in hypoxic neuronal death and that excessive production of CyPGs after stroke may exacerbate ischemic injury by modification and inhibition of UCH-L1.

Topics: Animals; Cell Hypoxia; Cells, Cultured; Disease Models, Animal; Hypoxia-Ischemia, Brain; Nerve Degeneration; Prostaglandin D2; Rats; Rats, Sprague-Dawley; Transduction, Genetic; Ubiquitin Thiolesterase

Chronic neuroinflammation is implicated in Parkinson's disease (PD). Inflammation involves the activation of microglia and astrocytes that release high levels of prostaglandins. There is a profound gap in our understanding of how cyclooxygenases and their prostaglandin products redirect cellular events to promote PD neurodegeneration. The major prostaglandin in the mammalian brain is prostaglandin D2, which readily undergoes spontaneous dehydration to generate the bioactive cyclopentenone prostaglandins of the J2 series. These J2 prostaglandins are highly reactive and neurotoxic products of inflammation shown in cellular models to impair the ubiquitin/proteasome pathway and cause the accumulation of ubiquitinated proteins. PD is a disorder that exhibits accumulation of ubiquitinated proteins in neuronal inclusions (Lewy bodies). The role of J2 prostaglandins in promoting PD neurodegeneration has not been investigated under in vivo conditions.. We addressed the neurodegenerative and behavioral effects of the administration of prostaglandin J2 (PGJ2) simultaneously into the substantia nigra/striatum of adult male FVB mice by subchronic microinjections. One group received unilateral injections of DMSO (vehicle, n = 6) and three groups received PGJ2 [3.4 microg or 6.7 microg (n = 6 per group) or 16.7 microg (n = 5)] per injection. Immunohistochemical and behavioral analyses were applied to assess the effects of the subchronic PGJ2 microinfusions.. Immunohistochemical analysis demonstrated a PGJ2 dose-dependent significant and selective loss of dopaminergic neurons in the substantia nigra while the GABAergic neurons were spared. PGJ2 also triggered formation of aggregates immunoreactive for ubiquitin and alpha-synuclein in the spared dopaminergic neurons. Moreover, PGJ2 infusion caused a massive microglia and astrocyte activation that could initiate a deleterious cascade leading to self-sustained progressive neurodegeneration. The PGJ2-treated mice also exhibited locomotor and posture impairment.. Our studies establish the first model of inflammation in which administration of an endogenous highly reactive product of inflammation, PGJ2, recapitulates key aspects of PD. Our novel PGJ2-induced PD model strongly supports the view that localized and chronic production of highly reactive and neurotoxic prostaglandins, such as PGJ2, in the CNS could be an integral component of inflammation triggered by insults evoked by physical, chemical or microbial stimuli and thus establishes a link between neuroinflammation and PD neurodegeneration.

Topics: alpha-Synuclein; Animals; Cell Death; Disease Models, Animal; Dopamine; Dose-Response Relationship, Drug; Drug Administration Schedule; Encephalitis; Gliosis; Immunohistochemistry; Inclusion Bodies; Inflammation Mediators; Male; Mice; Microinjections; Movement Disorders; Nerve Degeneration; Neurons; Parkinsonian Disorders; Prostaglandin D2; Substantia Nigra

There is clear evidence that an inflammatory reaction is mounted within the CNS following trauma, stroke, infection and seizures, thus augmenting brain damage. Furthermore, chronic inflammation of the CNS is implicated in many neurodegenerative disorders. However, the effects of products of inflammation on neuronal cells are poorly understood. Herein, we characterize the effects of a neurotoxic product of inflammation, prostaglandin J2 (PGJ2), on catechol-O-methyltransferase (COMT) in human dopaminergic-like neuroblastoma SK-N-SH cells and rat (P2) cortical neurons. COMT metabolizes catechols and catecholamines, a pathway relevant to neurodegeneration. PGJ2 treatment reduced the expression and activity of COMT, induced its sequestration into perinuclear aggregates and potentiated dopamine toxicity. The large COMT aggregates were co-localized with the centrosome, suggesting an aggresome-like structure. Our results indicate that COMT impairment induced by PGJ2 treatment may increase the concentration of dopamine (or its metabolites) to neurotoxic levels. Thus, COMT impairment following pro-inflammatory events may be a potential risk factor in neurodegeneration.

Topics: Animals; Brain Damage, Chronic; Catechol O-Methyltransferase; Catechol O-Methyltransferase Inhibitors; Catecholamines; Cell Line, Tumor; Cerebral Cortex; Dopamine; Down-Regulation; Encephalitis; Humans; Inclusion Bodies; Inflammation Mediators; Nerve Degeneration; Neurons; Oxidative Stress; Prostaglandin D2; Rats

The mechanisms implicated in the aggregation of ubiquitinated proteins detected in neurodegenerative disorders remain elusive. We report that prostaglandin J2 (PGJ2), an endogenous product of inflammation, up-regulates sequestosome 1/p62 in a time- and dose-dependent manner in human neuroblastoma SK-N-SH cells. We previously demonstrated that prostaglandins of the J2 series inhibit ubiquitin hydrolases, such as UCH-L1. Herein, we show that sequestosome 1/p62 is co-localized with ubiquitinated proteins and the ubiquitin hydrolase UCH-L1 in cytoplasmic aggregates induced by PGJ2. Preventing sequestosome 1/p62 up-regulation by RNA interference abolishes the aggregation but not the accumulation of ubiquitinated proteins or PGJ2 cytotoxicity. Sequestosome 1/p62 is known to bind poly-ubiquitinated proteins through its ubiquitin-associated domain. Our data support the notion that sequestosome 1/p62 up-regulation under stress conditions contributes to the "sequestration" of poly-ubiquitinated proteins into aggregates. However, the overwhelming accumulation of ubiquitinated proteins, rather than their aggregation, is likely to be an important contributor to PGJ2 cytotoxicity.

Topics: Adaptor Proteins, Signal Transducing; Cell Death; Cell Line, Tumor; Dose-Response Relationship, Drug; Encephalitis; Humans; Inclusion Bodies; Nerve Degeneration; Nerve Tissue Proteins; Neurodegenerative Diseases; Neurons; Prostaglandin D2; Protein Binding; Proteins; RNA Interference; Sequestosome-1 Protein; Stress, Physiological; Time Factors; Ubiquitin; Ubiquitin Thiolesterase; Up-Regulation

Focal ischemia was induced in the fronto-parietal region of rat brain, by injection of Rose Bengal, followed by light activation. Focal ischemia was accompanied by formation of PGD(2) peaking 60-90 min post irradiation and declining thereafter. Increased Cycloxygenase-2 (COX-2) expression was also observed. Control ischemic rats showed distinct morphological alterations with necrosis of neurons, glial cells and blood vessels, surrounded by a halo with pyknotic cells with cytoplasm swelling and vacuolization. Compound SC58236, a selective COX-2 inhibitor, dose-dependently prevented, ischemia-induced eicosanoid formation (area under the curve (AUC) of controls: 3.11 +/- 0.87; AUC of 20 mg/kg SC58236: 0.39 +/- 0.24), and caused significant reduction of damaged area (30.7 and 18.9% at SC58236 20 and 6.6 mg/kg), suggesting that selective inhibitors of COX-2 are neuroprotective.

Topics: Animals; Brain Ischemia; Cerebral Cortex; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Disease Models, Animal; Dose-Response Relationship, Drug; Fluorescent Dyes; Isoenzymes; Male; Microdialysis; Microscopy, Electron; Necrosis; Nerve Degeneration; Neurons; Neuroprotective Agents; Prostaglandin D2; Prostaglandin-Endoperoxide Synthases; Pyrazoles; Rats; Rats, Wistar; Rose Bengal; Sulfonamides