title: Parkin reverses intracellular beta-amyloid accumulation and its negative effects on proteasome function.
abstract: The significance of intracellular beta-amyloid (Abeta(42)) accumulation is increasingly recognized in Alzheimer's disease (AD) pathogenesis. Abeta removal mechanisms that have attracted attention include IDE/neprilysin degradation and antibody-mediated uptake by immune cells. However, the role of the ubiquitin-proteasome system (UPS) in the disposal of cellular Abeta has not been fully explored. The E3 ubiquitin ligase Parkin targets several proteins for UPS degradation, and Parkin mutations are the major cause of autosomal recessive Parkinson's disease. We tested whether Parkin has cross-function to target misfolded proteins in AD for proteasome-dependent clearance in SH-SY5Y and primary neuronal cells. Wild-type Parkin greatly decreased steady-state levels of intracellular Abeta(42), an action abrogated by proteasome inhibitors. Intracellular Abeta(42) accumulation decreased cell viability and proteasome activity. Accordingly, Parkin reversed both effects. Changes in mitochondrial ATP production from Abeta or Parkin did not account for their effects on the proteasome. Parkin knock-down led to accumulation of Abeta. In AD brain, Parkin was found to interact with Abeta and its levels were reduced. Thus, Parkin is cytoprotective, partially by increasing the removal of cellular Abeta through a proteasome-dependent pathway.
authors.affiliation: Department of Neurology, Tufts University School of Medicine, Boston, Massachusetts, USA.
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Rosen
authors.forename: Charbel E-H
authors.initials: CE
authors.lastname: Moussa
authors.forename: Han-Kyu
authors.initials: HK
authors.lastname: Lee
authors.forename: Pravir
authors.initials: P
authors.lastname: Kumar
authors.forename: Tohru
authors.initials: T
authors.lastname: Kitada
authors.forename: Gangjian
authors.initials: G
authors.lastname: Qin
authors.forename: Qinghao
authors.initials: Q
authors.lastname: Fu
authors.forename: Henry W
authors.initials: HW
authors.lastname: Querfurth
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000544:Alzheimer Disease / Q000235:genetics / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002470:Cell Survival / Q000235:genetics; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism; D019610:Cytoprotection / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000502:physiology*
chemical_list: D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; D025801:Ubiquitin; C075222:amyloid beta-protein (1-42); D000255:Adenosine Triphosphate; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex