Derlin-1 and p97/valosin-containing protein mediate the endoplasmic reticulum-associated degradation of human V2 vasopressin receptors.
The endoplasmic reticulum-associated degradation (ERAD), the main quality control pathway of the cell, is crucial for the elimination of unfolded or misfolded proteins. Several diseases are associated with the retention of misfolded proteins in the early secretory pathway. Among them is X-linked nephrogenic diabetes insipidus, caused by mutations in the gene encoding the V2 vasopressin receptor (V2R). We studied the degradation pathways of three intracellularly retained V2R mutants with different misfolded domains in human embryonic kidney 293 cells. At steady state, the wild-type V2R and the complex-glycosylated mutant G201D were partially located in lysosomes, whereas core-glycosylated mutants L62P and V226E were excluded from this compartment. In pulse-chase experiments, proteasomal inhibition stabilized the nonglycosylated and core-glycosylated forms of all studied receptors. In addition, all mutants and the wild-type receptor were found to be polyubiquitinylated. Nonglycosylated and core-glycosylated receptor forms were located in cytosolic and membrane fractions, respectively, confirming the deglycosylation and retrotranslocation of ERAD substrates to the cytosol. Distinct Derlin-1-dependent and -independent ERAD pathways have been proposed for proteins with different misfolded domains (cytosolic, extracellular, and membrane) in yeast. Here, we show for the first time that V2R mutants with different misfolded domains are able to coprecipitate the ERAD components p97/valosin-containing protein, Derlin-1 and the 26S proteasome regulatory subunit 7. Our results demonstrate the presence of a Derlin-1-mediated ERAD pathway degrading wild-type and disease-causing V2R mutants with different misfolded domains in a mammalian system.
Leibniz-Institut für Molekulare Pharmakologie (FMP), Campus Buch, Robert-Rössle Str. 10, 13125 Berlin, Germany.
Isabel
I
Schwieger
Katja
K
Lautz
Eberhard
E
Krause
Walter
W
Rosenthal
Burkhard
B
Wiesner
Ricardo
R
Hermosilla
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000262:Adenylyl Cyclases / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001127:Arginine Vasopressin / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D002738:Chloroquine / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000166:cytology; D008247:Lysosomes / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids; D017434:Protein Structure, Tertiary; D017483:Receptors, Vasopressin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D014162:Transfection; D054875:Ubiquitination; D000074405:Valosin Containing Protein
D018797:Cell Cycle Proteins; C487709:DERL1 protein, human; D008565:Membrane Proteins; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D049452:Green Fluorescent Proteins; D002738:Chloroquine; D000251:Adenosine Triphosphatases; C000614178:VCP protein, human; D000074405:Valosin Containing Protein; D000262:Adenylyl Cyclases