acetyl-aspartyl-glutamyl-valyl-aspartal and Parkinson-Disease

Nerve growth factor (NGF) mediates a variety of nerve cell actions through receptor tyrosine kinase TrkA. It has been revealed that the Akt pathway contributes to the prevention of apoptosis. It is thought that Parkinson's disease involves apoptosis, and NGF prevents apoptosis in an in vivo model system. However, there is no evidence that the Akt pathway helps to prevent parkinsonism. Here, we report that NGF prevents apoptosis induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in PC12 cells as an in vitro model system of parkinsonism and that this survival effect diminishes on addition of LY294002, a specific inhibitor of phosphatidylinositol 3-kinase. Immunocytochemical analysis revealed that 1 mM MPTP-treated cells or dominant negative Akt-expressing cells, to which were added NGF and MPTP, undergo apoptosis. Moreover, the caspase-3-like activity is increased by addition of MPTP or MPTP with NGF and LY294002. The importance of another signal pathway is shown by PD98059, a specific inhibitor of MAP kinase (MAPK) kinase, but PD98059 does not alter the survival effect in this model system. These results indicate that the Akt pathway helps to prevent parkinsonism by suppressing caspase-3-like activity, but the MAPK pathway is not involved in the NGF-dependent survival enhancing effect in this model system.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Amino Acid Chloromethyl Ketones; Amino Acid Substitution; Animals; Apoptosis; Caspase 3; Caspases; Chromones; Coumarins; Cysteine Proteinase Inhibitors; Dopamine Agents; Drug Evaluation, Preclinical; Enzyme Inhibitors; Flavonoids; Genes, Dominant; MAP Kinase Signaling System; Mitogen-Activated Protein Kinases; Morpholines; Mutagenesis, Site-Directed; Neoplasm Proteins; Nerve Growth Factor; Oligopeptides; Parkinson Disease; Parkinsonian Disorders; PC12 Cells; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphoserine; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Rats; Recombinant Fusion Proteins; Signal Transduction; Transfection

An endogenous dopamine-derived N-methyl(R)salsolinol has been suggested to be involved in the pathogenesis of Parkinson's disease. In Parkinson's disease, the level of N-methyl(R)salsolinol increased in cerebrospinal fluid and the high activity of a synthesizing enzyme, (R)salsolinol N-methyltransferase, was detected in lymphocytes. This isoquinoline induced apoptotic DNA damage in human dopaminergic neuroblastoma SH-SY5Y cells. Among catechol isoquinolines, only N-methylsalsolinol induced apoptosis in the cells, and the scavengers of hydroxyl radicals and antioxidants suppressed DNA damage, suggesting that reactive oxygen species initiate apoptosis. The isoquinoline activated caspase-3 like proteases and a caspase-3 inhibitor protected the cells from DNA damage. (-)Deprenyl, but neither clorgyline nor pargyline, prevented apoptotic cell death. The mechanism of the protection was due to stabilization of mitochondrial membrane potential reduced by the toxin. In Parkinson's disease apoptosis may be induced in dopamine neurons by this endogenous neurotoxin, and (-)deprenyl may protect them from apoptotic death process.

Topics: Apoptosis; Caspase 3; Caspase Inhibitors; Caspases; Cysteine Proteinase Inhibitors; Dopamine; Enzyme Activation; Female; Humans; Male; Neuroprotective Agents; Oligopeptides; Parkinson Disease; Salsoline Alkaloids; Selegiline; Tetrahydroisoquinolines; Tumor Cells, Cultured

An endogenous neurotoxin, N-methyl(R)salsolinol, has been proved to be involved in the pathogenesis of Parkinson's disease. Increased level of N-methyl(R)salsolinol in the cerebrospinal fluid and high activity of its synthesizing (R)salsolinol N-methyltransferase in lymphocytes were confirmed in the majority of parkinsonian patients. Recently this neurotoxin was found to induce apoptosis in human dopaminergic neuroblastoma SH-SY5Y cells. In this study, we tried to elucidate the intracellular mechanism of apoptosis induced by N-methyl(R)salsolinol, and proved activation of caspase 3 after incubation with this toxin by Western blot analysis. Further, a caspase 3 inhibitor, acetyl-L-aspartyl-L-glutamyl-L-valyl-L-aspartic aldehyde, prevented the nucleosomal DNA fragmentation completely. These results demonstrate that caspase 3 mediates apoptosis induced by an endogenous neurotoxin, N-methyl(R)salsolinol, which may cause apoptotic cell death of dopamine neurons in Parkinson's disease.

Topics: Apoptosis; Caspase 3; Caspase Inhibitors; Caspases; DNA Fragmentation; Enzyme Activation; Enzyme Precursors; Humans; Neurotoxins; Oligopeptides; Parkinson Disease; Salsoline Alkaloids; Tetrahydroisoquinolines; Tumor Cells, Cultured