1-Methyl-4-phenylpyridinium affects fast axonal transport by activation of caspase and protein kinase C

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 104; no. 7; pp. 2442 - 2447
• Main Authors: Morfini, G, Pigino, G, Opalach, K, Serulle, Y, Moreira, J.E, Sugimori, M, Llinás, R.R, Brady, S.T
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 13.02.2007; National Acad Sciences
• Subjects: 1-Methyl-4-phenylpyridinium - pharmacology; Alzheimers disease; Animals; Axonal Transport - drug effects; Axons; Biological Sciences; Caspases - metabolism; Decapodiformes; Disease Models, Animal; Enzyme Activation - drug effects; Fats; Kinases; Kinetics; Nervous system diseases; Neurodegenerative diseases; Neurology; Neurons; Neurons - pathology; Parkinson disease; Parkinson Disease - etiology; Parkinson Disease - pathology; Parkinson's disease; Perfusion; Protein isoforms; Protein Kinase C - metabolism; Protein Kinase C-delta - metabolism; Synapses; Synaptic Vesicles - drug effects
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0611231104

Parkinson's disease (PD), a late-onset condition characterized by dysfunction and loss of dopaminergic neurons in the substantia nigra, has both sporadic and neurotoxic forms. Neurotoxins such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and its metabolite 1-methyl-4-phenylpyridinium (MPP+) induce PD symptoms and recapitulate major pathological hallmarks of PD in human and animal models. Both sporadic and MPP+-induced forms of PD proceed through a "dying-back" pattern of neuronal degeneration in affected neurons, characterized by early loss of synaptic terminals and axonopathy. However, axonal and synaptic-specific effects of MPP+ are poorly understood. Using isolated squid axoplasm, we show that MPP+ produces significant alterations in fast axonal transport (FAT) through activation of a caspase and a previously undescribed protein kinase C (PKCδ) isoform. Specifically, MPP+ increased cytoplasmic dynein-dependent retrograde FAT and reduced kinesin-1-mediated anterograde FAT. Significantly, MPP+ effects were independent of both nuclear activities and ATP production. Consistent with its effects on FAT, MPP+ injection in presynaptic domains led to a dramatic reduction in the number of membranous profiles. Changes in availability of synaptic and neurotrophin-signaling components represent axonal and synaptic-specific effects of MPP+ that would produce a dying-back pathology. Our results identify a critical neuronal process affected by MPP+ and suggest that alterations in vesicle trafficking represent a primary event in PD pathogenesis. We propose that PD and other neurodegenerative diseases exhibiting dying-back neuropathology represent a previously undescribed category of neurological diseases characterized by dysfunction of vesicle transport and associated with the loss of synaptic function.