Polarized sorting of the copper transporter ATP7B in neurons mediated by recognition of a dileucine signal by AP-1.
Neurons are highly polarized cells having distinct somatodendritic and axonal domains. Here we report that polarized sorting of the Cu(2+) transporter ATP7B and the vesicle-SNARE VAMP4 to the somatodendritic domain of rat hippocampal neurons is mediated by recognition of dileucine-based signals in the cytosolic domains of the proteins by the σ1 subunit of the clathrin adaptor AP-1. Under basal Cu(2+) conditions, ATP7B was localized to the trans-Golgi network (TGN) and the plasma membrane of the soma and dendrites but not the axon. Mutation of a dileucine-based signal in ATP7B or overexpression of a dominant-negative σ1 mutant resulted in nonpolarized distribution of ATP7B between the somatodendritic and axonal domains. Furthermore, addition of high Cu(2+) concentrations, previously shown to reduce ATP7B incorporation into AP-1-containing clathrin-coated vesicles, caused loss of TGN localization and somatodendritic polarity of ATP7B. These findings support the notion of AP-1 as an effector of polarized sorting in neurons and suggest that altered polarity of ATP7B in polarized cell types might contribute to abnormal copper metabolism in the MEDNIK syndrome, a neurocutaneous disorder caused by mutations in the σ1A subunit isoform of AP-1.
Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.
Shweta
S
Jain
Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.
Ginny G
GG
Farías
Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892 bonifacinoj@helix.nih.gov.
Juan S
JS
Bonifacino
D033961:Adaptor Protein Complex 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D034002:Adaptor Protein Complex sigma Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D027682:Cation Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity; D002478:Cells, Cultured; D003300:Copper / Q000378:metabolism / Q000494:pharmacology; D000073840:Copper-Transporting ATPases; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007930:Leucine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D050683:R-SNARE Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051381:Rats; D021601:trans-Golgi Network / Q000378:metabolism
D033961:Adaptor Protein Complex 1; D034002:Adaptor Protein Complex sigma Subunits; D027682:Cation Transport Proteins; D050683:R-SNARE Proteins; C533192:VAMP4 protein, rat; D049452:Green Fluorescent Proteins; D003300:Copper; D000251:Adenosine Triphosphatases; C550619:Atp7b protein, rat; D000073840:Copper-Transporting ATPases; D007930:Leucine