Multiple phosphorylation of alpha-synuclein by protein tyrosine kinase Syk prevents eosin-induced aggregation.
The presence of aggregated alpha-synuclein molecules is a common denominator in a variety of neurodegenerative disorders. Here, we show that alpha-synuclein (alpha-syn) is an outstanding substrate for the protein tyrosine kinase p72syk (Syk), which phosphorylates three tyrosyl residues in its C-terminal domain (Y-125, Y-133, and Y-136), as revealed from experiments with mutants where these residues have been individually or multiply replaced by phenylalanine. In contrast, only Y-125 is phosphorylated by Lyn and c-Fgr. Eosin-induced multimerization is observed with wild-type alpha-syn, either phosphorylated or not by Lyn, and with all its Tyr to Phe mutants but not with the protein previously phosphorylated by Syk. Syk-mediated phosphorylation also counteracts alpha-syn assembly into filaments as judged from the disappearance of alpha-syn precipitated upon centrifugation at 100,000 x g. We also show that Syk and alpha-syn colocalize in the brain, and upon cotransfection in Chinese hamster ovary cells, alpha-syn becomes Tyr-phosphorylated by Syk. Moreover, Syk and alpha-syn interact with each other as judged from the mammalian two-hybrid system approach. These data suggest that Syk or tyrosine kinase(s) with similar specificity may play an antineurodegenerative role by phosphorylating a-syn, thereby preventing its aggregation.
Negro
Alessandro
A
Dipartimento di Chimica Biologica and Centro di Studio delle Biomembrane del C.N.R., University of Padova, Padova, Italy.
Brunati
Anna Maria
AM
Donella-Deana
Arianna
A
Massimino
Maria Lina
ML
Pinna
Lorenzo A
LA
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D019281:Dimerization; D004792:Enzyme Precursors / Q000235:genetics / Q000378:metabolism*; D004801:Eosine Yellowish-(YS) / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D000072377:Syk Kinase; D051843:Synucleins; D051844:alpha-Synuclein
D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D010710:Phosphates; D051843:Synucleins; D051844:alpha-Synuclein; D011505:Protein-Tyrosine Kinases; D000072377:Syk Kinase; D004801:Eosine Yellowish-(YS)