u-0126 and Neurodegenerative-Diseases

Oxidative stress due to reactive oxygen species plays a central role in pathophysiology of neurodegenerative diseases. Inhibition of mitogen-activated protein kinase (MAPK) cascades attenuates the oxidative induced cell stress and behaves as potential neuroprotection agent.. In this study, we evaluate hydrogen peroxide induced neural cell stress and determine how different MAPK inhibitors restore the cell damage.. The results indicated that oxidative stress induced by neural cell damage commonly exists, and MAPK inhibitors partially and selectively attenuated the cell damage by reducing ROS production and cell apoptosis. The cultured neurons are more susceptible to hydrogen peroxide than subculture cells.. We conclude that the essential role of different MAPK inhibitors is to attenuate the hydrogen peroxide induced neuronal cell damage. Those data broaden the implication between individual neural cells and different MAPK inhibitors and give clues for oxidative stress induced neural diseases.

Topics: Animals; Anthracenes; Butadienes; Cell Survival; Enzyme Inhibitors; Humans; Hydrogen Peroxide; Imidazoles; Mice; Mitogen-Activated Protein Kinase Kinases; Neurodegenerative Diseases; Neurons; Nitriles; Oxidative Stress; PC12 Cells; Primary Cell Culture; Pyridines; Rats; Reactive Oxygen Species

Accelerating the clearance of intracellular protein aggregates through elevation of autophagy represents a viable approach for the treatment of neurodegenerative diseases. In our earlier report, we have demonstrated the enhanced degradation of mutant huntingtin protein aggregates through autophagy process induced by europium hydroxide nanorods [EHNs: Eu(III)(OH)3], but the underlying molecular mechanism of EHNs mediated autophagy was unclear. The present report reveals that EHNs induced autophagy does not follow the classical AKT-mTOR and AMPK signaling pathways. The inhibition of ERK1/2 phosphorylation using the specific MEK inhibitor U0126 partially abrogates the autophagy as well as the clearance of mutant huntingtin protein aggregates mediated by EHNs suggesting that nanorods stimulate the activation of MEK/ERK1/2 signaling pathway during autophagy process. In contrast, another mTOR-independent autophagy inducer trehalose has been found to induce autophagy without activating ERK1/2 signaling pathway. Interestingly, the combined treatment of EHNs and trehalose leads to more degradation of mutant huntingtin protein aggregates than that obtained with single treatment of either nanorods or trehalose. Our results demonstrate the rational that further enhanced clearance of intracellular protein aggregates, needed for diverse neurodegenerative diseases, may be achieved through the combined treatment of two or more autophagy inducers, which stimulate autophagy through different signaling pathways.

Topics: Adenine; Androstadienes; Animals; Autophagy; Autophagy-Related Protein 5; Butadienes; Cell Line, Tumor; Cell Survival; Chloroquine; Europium; Extracellular Signal-Regulated MAP Kinases; Green Fluorescent Proteins; HeLa Cells; Humans; Huntingtin Protein; Hydroxides; Lysosomes; Macrolides; Mice; Microscopy, Fluorescence; Microtubule-Associated Proteins; Nanotubes; Nerve Tissue Proteins; Neurodegenerative Diseases; Nitriles; Phagosomes; Phosphorylation; RNA, Small Interfering; Signal Transduction; TOR Serine-Threonine Kinases; Trehalose; Wortmannin

Inflammation in Parkinson's disease is closely associated with disease pathogenesis. Mutations in Omi, which encodes the protease Omi, are linked to neurodegeneration and Parkinson's disease in humans and in mouse models. The severe neurodegeneration and neuroinflammation that occur in mnd2 (motor neuron degeneration 2) mice result from loss of the protease activity of Omi by the point mutation S276C; however, the substrates of Omi that induce neurodegeneration are unknown. We showed that Omi was required for the production of inflammatory molecules by microglia, which are the resident macrophages in the central nervous system. Omi suppressed the activation of the mitogen-activated protein kinases (MAPKs) extracellular signal-regulated kinase 1 and 2 (ERK1/2) by cleaving the upstream kinase MEK1 (mitogen-activated or extracellular signal-regulated protein kinase kinase 1). Knockdown of Omi in microglial cell lines led to activation of ERK1/2 and resulted in degradation of IκBα [α inhibitor of nuclear factor κB (NF-κB)], resulting in NF-κB activation and the expression of genes encoding inflammatory molecules, such as tumor necrosis factor-α and inducible nitric oxide synthase. The production of inflammatory molecules induced by the knockdown of Omi was blocked by the MEK1-specific inhibitor U0126. Furthermore, expression of the protease-deficient S276C Omi mutant in a microglial cell line had no effect on MEK1 cleavage or ERK1/2 activation. In the brains of mnd2 mice, we observed increased transcription of several genes encoding inflammatory molecules, as well as activation of astrocytes and microglia. Therefore, our study demonstrates that Omi is an intrinsic cellular factor that inhibits neuroinflammation.

Topics: Animals; Blotting, Western; Butadienes; Cell Line; Cell Line, Tumor; Enzyme Inhibitors; High-Temperature Requirement A Serine Peptidase 2; Humans; I-kappa B Proteins; Inflammation; MAP Kinase Kinase 1; Mice; Mice, Inbred C57BL; Microglia; Mitochondrial Proteins; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Neurodegenerative Diseases; NF-kappa B; NF-KappaB Inhibitor alpha; Nitric Oxide Synthase Type II; Nitriles; Point Mutation; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Serine Endopeptidases; Signal Transduction; Tumor Necrosis Factor-alpha

Extracellular signal-regulated kinase (ERK) belongs to the family of mitogen-activated protein kinases (MAPKs), which are serine-threonine kinases activated by phosphorylation in response to a variety of mitogenic signals. We previously reported that 17 beta-estradiol rapidly activates ERK in the rat hippocampus. However, the physiological role of this rapid activation of ERK by estrogen in vivo has not yet been elucidated. This study investigated whether ERK may participate in mediating the neuroprotective effects of estrogen against quinolinic acid (QA) toxicity in the rat hippocampus in vivo. Injection of QA into the hippocampi of male rats produced a loss of Nissl-stained neurons in the CA1 after 24 h. Prior administration of 17 beta-estradiol (50 pmol/animal) to the ventricles prevented the QA-induced decrease in Nissl-stained neurons. Pretreatment with U0126, an inhibitor of MAPK/ERK kinase, inhibited the rapid activation of ERK by 17 beta-estradiol in the rat hippocampus. Moreover, the neuroprotective effects of 17beta-estradiol against QA toxicity were blocked by the pretreatment with U0126. U0126 alone did not produce a loss of neurons. These results indicate that ERK mediates estrogen neuroprotection after QA toxicity in the rat hippocampus.

Topics: Animals; Butadienes; Cell Death; Enzyme Inhibitors; Estradiol; Extracellular Space; Hippocampus; Injections, Intraventricular; Male; MAP Kinase Signaling System; Neurodegenerative Diseases; Neurons; Neuroprotective Agents; Nitriles; Phosphorylation; Quinolinic Acid; Rats; Rats, Sprague-Dawley