title: RAB-10 regulates glutamate receptor recycling in a cholesterol-dependent endocytosis pathway.
abstract: Regulated endocytosis of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type glutamate receptors (AMPARs) is critical for synaptic plasticity. However, the specific combination of clathrin-dependent and -independent mechanisms that mediate AMPAR trafficking in vivo have not been fully characterized. Here, we examine the trafficking of the AMPAR subunit GLR-1 in Caenorhabditis elegans. GLR-1 is localized on synaptic membranes, where it regulates reversals of locomotion in a simple behavioral circuit. Animals lacking RAB-10, a small GTPase required for endocytic recycling of intestinal cargo, are similar in phenotype to animals lacking LIN-10, a postsynaptic density 95/disc-large/zona occludens-domain containing protein: GLR-1 accumulates in large accretions and animals display a decreased frequency of reversals. Mutations in unc-11 (AP180) or itsn-1 (Intersectin 1), which reduce clathrin-dependent endocytosis, suppress the lin-10 but not rab-10 mutant phenotype, suggesting that LIN-10 functions after clathrin-mediated endocytosis. By contrast, cholesterol depletion, which impairs lipid raft formation and clathrin-independent endocytosis, suppresses the rab-10 but not the lin-10 phenotype, suggesting that RAB-10 functions after clathrin-independent endocytosis. Animals lacking both genes display additive GLR-1 trafficking defects. We propose that RAB-10 and LIN-10 recycle AMPARs from intracellular endosomal compartments to synapses along distinct pathways, each with distinct sensitivities to cholesterol and the clathrin-mediated endocytosis machinery.
authors.affiliation: Department of Genetics, Rutgers University, Piscataway, NJ 08854, USA.
authors.forename: Doreen R
authors.initials: DR
authors.lastname: Glodowski
authors.forename: Carlos Chih-Hsiung
authors.initials: CC
authors.lastname: Chen
authors.forename: Henry
authors.initials: H
authors.lastname: Schaefer
authors.forename: Barth D
authors.initials: BD
authors.lastname: Grant
authors.forename: Christopher
authors.initials: C
authors.lastname: Rongo
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D002784:Cholesterol / Q000494:pharmacology*; D004705:Endocytosis / Q000187:drug effects*; D008565:Membrane Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010641:Phenotype; D018091:Receptors, AMPA / Q000378:metabolism; D017470:Receptors, Glutamate / Q000378:metabolism*; D015398:Signal Transduction; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D029742:Caenorhabditis elegans Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; C096470:glr-1 protein, C elegans; C064105:lin-10 protein, C elegans; C120753:unc-11 protein, C elegans; D002784:Cholesterol; C510977:RAB-10 protein, C elegans; D020691:rab GTP-Binding Proteins