title: KEL-8 is a substrate receptor for CUL3-dependent ubiquitin ligase that regulates synaptic glutamate receptor turnover.
abstract: The regulated localization of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-type glutamate receptors (AMPARs) to synapses is an important component of synaptic signaling and plasticity. Regulated ubiquitination and endocytosis determine the synaptic levels of AMPARs, but it is unclear which factors conduct these processes. To identify genes that regulate AMPAR synaptic abundance, we screened for mutants that accumulate high synaptic levels of the AMPAR subunit GLR-1 in Caenorhabditis elegans. GLR-1 is localized to postsynaptic clusters, and mutants for the BTB-Kelch protein KEL-8 have increased GLR-1 levels at clusters, whereas the levels and localization of other synaptic proteins seem normal. KEL-8 is a neuronal protein and is localized to sites adjacent to GLR-1 postsynaptic clusters along the ventral cord neurites. KEL-8 is required for the ubiquitin-mediated turnover of GLR-1 subunits, and kel-8 mutants show an increased frequency of spontaneous reversals in locomotion, suggesting increased levels of GLR-1 are present at synapses. KEL-8 binds to CUL-3, a Cullin 3 ubiquitin ligase subunit that we also find mediates GLR-1 turnover. Our findings indicate that KEL-8 is a substrate receptor for Cullin 3 ubiquitin ligases that is required for the proteolysis of GLR-1 receptors and suggest a novel postmitotic role in neurons for Kelch/CUL3 ubiquitin ligases.
authors.affiliation: Department of Genetics, The Waksman Institute, Rutgers University, Piscataway, NJ 08854, USA.
authors.forename: Henry
authors.initials: H
authors.lastname: Schaefer
authors.forename: Christopher
authors.initials: C
authors.lastname: Rongo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000378:metabolism*; D044842:Cullin Proteins / Q000378:metabolism*; D003712:Dendrites / Q000378:metabolism; D029721:Drosophila Proteins / Q000737:chemistry; D005091:Exons / Q000235:genetics; D007438:Introns / Q000235:genetics; D008840:Microfilament Proteins / Q000737:chemistry; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009474:Neurons / Q000166:cytology; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D018091:Receptors, AMPA / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013569:Synapses / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; D044842:Cullin Proteins; D029721:Drosophila Proteins; C510975:Kel-8 protein, C elegans; D008840:Microfilament Proteins; D018091:Receptors, AMPA; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D025801:Ubiquitin; C096470:glr-1 protein, C elegans; C080353:kel protein, Drosophila; C510976:CUL-3 protein, C elegans; D044767:Ubiquitin-Protein Ligases