ABSTRACT
Aß (beta-amyloid peptide) is an important contributor to Alzheimer's disease (AD). We modeled Aß toxicity in yeast by directing the peptide to the secretory pathway. A genome-wide screen for toxicity modifiers identified the yeast homolog of phosphatidylinositol binding clathrin assembly protein (PICALM) and other endocytic factors connected to AD whose relationship to Aß was previously unknown. The factors identified in yeast modified Aß toxicity in glutamatergic neurons of Caenorhabditis elegans and in primary rat cortical neurons. In yeast, Aß impaired the endocytic trafficking of a plasma membrane receptor, which was ameliorated by endocytic pathway factors identified in the yeast screen. Thus, links between Aß, endocytosis, and human AD risk factors can be ascertained with yeast as a model system.
Subject(s)
Alzheimer Disease/genetics , Alzheimer Disease/metabolism , Amyloid beta-Peptides/metabolism , Endocytosis , Peptide Fragments/metabolism , Saccharomyces cerevisiae , Amyloid beta-Peptides/chemistry , Amyloid beta-Peptides/genetics , Animals , Animals, Genetically Modified , Caenorhabditis elegans/cytology , Caenorhabditis elegans/genetics , Caenorhabditis elegans/metabolism , Cell Membrane/metabolism , Cells, Cultured , Clathrin/metabolism , Cytoskeleton/metabolism , Disease Susceptibility , Genetic Association Studies , Genetic Testing , Glutamates/metabolism , Humans , Monomeric Clathrin Assembly Proteins/genetics , Monomeric Clathrin Assembly Proteins/metabolism , Neurons/physiology , Peptide Fragments/chemistry , Peptide Fragments/genetics , Protein Multimerization , Protein Transport , Rats , Risk Factors , Saccharomyces cerevisiae/cytology , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/growth & development , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/genetics , Saccharomyces cerevisiae Proteins/metabolism , Secretory PathwayABSTRACT
Autophagy is a pathway for bulk degradation of subcellular constituents that is hyperactivated in many neurodegenerative conditions. It has been considered a second form of programmed cell death. Death of cerebellar Purkinje cells in lurcher animals is due to a mutation in GluRdelta2 that results in its constitutive activation. Here we have identified protein interactions between GluRdelta2, a novel isoform of a PDZ domain-containing protein (nPIST) that binds to this receptor, and Beclin1. nPIST and Beclin1 can synergize to induce autophagy. GluRdelta2(Lc), but not GluRdelta2(wt), can also induce autophagy. Furthermore, dying lurcher Purkinje cells contain morphological hallmarks of autophagic death in vivo. These results provide strong evidence that a direct link exists between GluRdelta2(Lc) receptor and stimulation of the autophagic pathway in dying lurcher Purkinje cells.
