alpha-synuclein and pervanadate

alpha-Synuclein has been implicated in the pathogenesis of many neurodegenerative diseases, including Parkinson's disease and Alzheimer's disease. Although the function of alpha-synuclein remains largely unknown, recent studies have demonstrated that this protein can interact with phospholipids. To address the role of alpha-synuclein in neurodegenerative disease, we have investigated whether it binds phospholipase D (PLD) and affects PLD activity in human embryonic kidney (HEK)-293 cells overexpressing wild type alpha-synuclein or the mutant forms of alpha-synuclein (A53T, A30P) associated with Parkinson's disease. Tyrosine phosphorylation of alpha-synuclein appears to play a modulatory role in the inhibition of PLD, because mutation of Tyr(125) to Phe slightly increases inhibitory effect of alpha-synuclein on PLD activity. Treatment with pervanadate or phorbol myristate acetate inhibits PLD more in HEK 293 cells overexpressing alpha-synuclein than in control cells. Binding of alpha-synuclein to PLD requires phox and pleckstrin homology domain of PLD and the amphipathic repeat region and non-Abeta component of alpha-synuclein. Although biologically important, co-transfection studies indicate that the interaction of alpha-synuclein with PLD does not influence the tendency of alpha-synuclein to form pathological inclusions. These results suggest that the association of alpha-synuclein with PLD, and modulation of PLD activity, is biologically important, but PLD does not appear to play an essential role in the pathophysiology of alpha-synuclein.

Topics: alpha-Synuclein; Animals; Blood Proteins; Blotting, Western; Brain; Cell Line; Cytoplasm; DNA, Complementary; Enzyme Activation; Enzyme Inhibitors; Eosinophils; Glutathione Transferase; Humans; Microscopy, Fluorescence; Mutation; Nerve Tissue Proteins; Phospholipase D; Phosphoproteins; Phosphorylation; Precipitin Tests; Protein Binding; Protein Isoforms; Protein Structure, Tertiary; Rats; Recombinant Fusion Proteins; Synucleins; Tetradecanoylphorbol Acetate; Time Factors; Transfection; Tyrosine; Vanadates