ABSTRACT
Exposure of alpha-synuclein (alphaS), a major component of Lewy bodies in Parkinson's disease, to polyunsaturated fatty acids (PUFAs) triggers the formation of soluble alphaS oligomers. Here, we demonstrate that PUFA binds recombinant alphaS protein through its N-terminal region (residues 2-60). In HEK293 cells, alphaS mutants lacking the N-terminal region failed to form oligomers in the presence of PUFA. The PUFA-induced alphaS oligomerization was accelerated by C-terminal truncation or Ser129 phosphorylation of alphaS; however, this effect was abolished by deletion of the N-terminus. The results indicate that the N-terminus of alphaS is essential for the PUFA-induced alphaS oligomerization.
Subject(s)
Fatty Acids, Unsaturated/metabolism , Parkinson Disease/metabolism , alpha-Synuclein/metabolism , Amino Acid Sequence/genetics , Cell Line , DNA Mutational Analysis , Fatty Acids, Unsaturated/pharmacology , Humans , Parkinson Disease/genetics , Phosphorylation , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Sequence Deletion , Serine/genetics , Serine/metabolism , alpha-Synuclein/geneticsABSTRACT
Sporadic Parkinson's disease (sPD) is a common neurodegenerative disorder, characterized by selective degeneration of dopaminergic neurons in the substantia nigra. Although the pathogenesis of the disease remains undetermined, phosphorylation of alpha-synuclein and its oligomer formation seem to play a key role. However, the protein kinase(s) involved in the phosphorylation in the pathogenesis of sPD has not been identified. Here, we found that G-protein-coupled receptor kinase 5 (GRK5) accumulated in Lewy bodies and colocalized with alpha-synuclein in the pathological structures of the brains of sPD patients. In cotransfected cells, GRK5 phosphorylated Ser-129 of alpha-synuclein at the plasma membrane and induced translocation of phosphorylated alpha-synuclein to the perikaryal area. GRK5-catalyzed phosphorylation also promoted the formation of soluble oligomers and aggregates of alpha-synuclein. Genetic association study revealed haplotypic association of the GRK5 gene with susceptibility to sPD. The haplotype contained two functional single-nucleotide polymorphisms, m22.1 and m24, in introns of the GRK5 gene, which bound to YY1 (Yin Yang-1) and CREB-1 (cAMP response element-binding protein 1), respectively, and increased transcriptional activity of the reporter gene. The results suggest that phosphorylation of alpha-synuclein by GRK5 plays a crucial role in the pathogenesis of sPD.
Subject(s)
Brain/enzymology , Kidney/enzymology , Lewy Bodies/enzymology , Parkinson Disease/enzymology , Protein Serine-Threonine Kinases/metabolism , alpha-Synuclein/metabolism , Aged , Cell Line , Female , G-Protein-Coupled Receptor Kinase 5 , Humans , Male , Recurrence , Tissue DistributionABSTRACT
POEMS syndrome is a rare plasma cell disorder, characterized by polyneuropathy, organomegaly, endocrinopathy, serum monoclonal protein, and skin lesions. Although not included in the acronym, renal lesions also are characteristic of this disease and sometimes require dialysis therapy. We treated a 61-year-old woman with POEMS syndrome with high-dose melphalan therapy (HDT) supported by autologous blood stem cell transplantation (SCT), and clinical remission was achieved. A repeated renal biopsy showed the striking effectiveness of this therapy on renal lesions. Pathological features of the renal lesions, such as membranoproliferative glomerulonephritis-like lesions, microangiopathic glomerulopathy, and mesangiolytic lesions with microcapillaries, almost completely disappeared. This treatment also markedly decreased serum levels of vascular endothelial growth factor (VEGF). These findings indicate that HDT with SCT is effective, even on renal lesions in patients with POEMS syndrome, and suggest that high serum VEGF concentrations are associated closely with the development of renal lesions in patients with this type of plasma cell disorder.
