Multiple aspects of homocysteine neurotoxicity: glutamate excitotoxicity, kinase hyperactivation and DNA damage
| Autor: | Daniela Ortiz, Eugene Rogers, Pei I. Ho, Thomas B. Shea |
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| Rok vydání: | 2002 |
| Předmět: |
S-Adenosylmethionine
Neurotoxins Excitotoxicity Hyperphosphorylation Glutamic Acid tau Proteins Biology medicine.disease_cause Receptors N-Methyl-D-Aspartate Cellular and Molecular Neuroscience Mice medicine Animals Phosphorylation Protein kinase A Homocysteine Cells Cultured Cerebral Cortex Neurons Dose-Response Relationship Drug Kinase Neurotoxicity Glutamate receptor medicine.disease Molecular biology Cell biology Enzyme Activation Oxidative Stress Metabotropic glutamate receptor NMDA receptor Calcium Mitogen-Activated Protein Kinases Protein Kinases DNA Damage |
| Zdroj: | Journal of neuroscience research. 70(5) |
| ISSN: | 0360-4012 |
| Popis: | Homocysteine (HC) is a neurotoxic amino acid that accumulates in several neurological disorders including Alzheimer's disease (AD). We examined the consequences of treatment of cultured murine cortical neurons with HC. Homocysteine-induced increases in cytosolic calcium, reactive oxygen species, phospho-tau immunoreactivity and externalized phosphatidyl serine (indicative of apoptosis). Homocysteine-induced calcium influx through NMDA channel activation, which stimulated glutamate excitotoxicity, as evidenced by treatment with antagonists of the NMDA channel and metabotropic glutamate receptors, respectively. The NMDA channel antagonist MK-801 reduced tau phosphorylation but not apoptosis after HC treatment, suggesting that HC-mediated apoptosis was not due to calcium influx. Apoptosis after HC treatment was reduced by co-treatment with 3-aminobenazmidine (3ab), an inhibitor of poly-ADP-ribosome polymerase (PARP), consistent with previous reports that ATP depletion by PARP-mediated repair of DNA strand breakage mediated HC-induced apoptosis. Treatment with 3ab did not reduce tau phosphorylation, however, therefore hyperphosphorylation of tau may not contribute to HC-induced apoptosis under these conditions. Inhibition of mitogen-activated protein kinase by co-treatment with the kinase inhibitor PD98059 inhibited tau phosphorylation but not apoptosis after HC treatment. HC accumulation reduces cellular levels of S-adenosyl methionine (SAM); co-treatment with SAM reduced apoptosis, suggesting that inhibition of critical methylation reactions may mediate HC-induced apoptosis. These findings indicate that HC compromises neuronal homeostasis by multiple, divergent routes. |
| Databáze: | OpenAIRE |
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