Systematic mutagenesis of ?-synuclein reveals distinct sequence requirements for physiological and pathological activities.
?-Synuclein is an abundant presynaptic protein that binds to phospholipids and synaptic vesicles. Physiologically, ?-synuclein functions as a SNARE-protein chaperone that promotes SNARE-complex assembly for neurotransmitter release. Pathologically, ?-synuclein mutations and ?-synuclein overexpression cause Parkinson's disease, and aggregates of ?-synuclein are found as Lewy bodies in multiple neurodegenerative disorders ("synucleinopathies"). ... The relation of the physiological functions to the pathological effects of ?-synuclein remains unclear. As an initial avenue of addressing this question, we here systematically examined the effect of ?-synuclein mutations on its physiological and pathological activities. We generated 26 ?-synuclein mutants spanning the entire molecule, and analyzed them compared with wild-type ?-synuclein in seven assays that range from biochemical studies with purified ?-synuclein, to analyses of ?-synuclein expression in cultured neurons, to examinations of the effects of virally expressed ?-synuclein introduced into the mouse substantia nigra by stereotactic injections. We found that both the N-terminal and C-terminal sequences of ?-synuclein were required for its physiological function as SNARE-complex chaperone, but that these sequences were not essential for its neuropathological effects. In contrast, point mutations in the central region of ?-synuclein, referred to as nonamyloid ? component (residues 61-95), as well as point mutations linked to Parkinson's disease (A30P, E46K, and A53T) increased the neurotoxicity of ?-synuclein but did not affect its physiological function in SNARE-complex assembly. Thus, our data show that the physiological function of ?-synuclein, although protective of neurodegeneration in some contexts, is fundamentally distinct from its neuropathological effects, thereby dissociating the two activities of ?-synuclein.
Mesh Terms:
Animals, Cells, Cultured, Disease Models, Animal, Gene Expression Regulation, Green Fluorescent Proteins, Hippocampus, Humans, Lipid Metabolism, Mice, Mice, Inbred C57BL, Mice, Knockout, Movement Disorders, Mutagenesis, Mutation, Neurons, Parkinson Disease, Phosphopyruvate Hydratase, Psychomotor Performance, SNARE Proteins, Substantia Nigra, Synaptosomal-Associated Protein 25, Syntaxin 1, Synucleins, Transduction, Genetic, Transfection, Tyrosine 3-Monooxygenase, Vesicle-Associated Membrane Protein 2
Animals, Cells, Cultured, Disease Models, Animal, Gene Expression Regulation, Green Fluorescent Proteins, Hippocampus, Humans, Lipid Metabolism, Mice, Mice, Inbred C57BL, Mice, Knockout, Movement Disorders, Mutagenesis, Mutation, Neurons, Parkinson Disease, Phosphopyruvate Hydratase, Psychomotor Performance, SNARE Proteins, Substantia Nigra, Synaptosomal-Associated Protein 25, Syntaxin 1, Synucleins, Transduction, Genetic, Transfection, Tyrosine 3-Monooxygenase, Vesicle-Associated Membrane Protein 2
J Neurosci
Date: Oct. 24, 2012
PubMed ID: 23100443
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