Pharmacochaperones post-translationally enhance cell surface expression by increasing conformational stability of wild-type and mutant vasopressin V2 receptors.
Some membrane-permeable antagonists restore cell surface expression of misfolded receptors retained in the endoplasmic reticulum (ER) and are therefore termed pharmacochaperones. Whether pharmacochaperones increase protein stability, thereby preventing rapid degradation, or assist folding via direct receptor interactions or interfere with quality control components remains elusive. We now show that the cell surface expression and function (binding of the agonist) of the mainly ER-retained wild-type murine vasopressin V2 receptor GFP fusion protein (mV2R.GFP) is restored by the vasopressin receptor antagonists SR49059 and SR121463B with EC50 values similar to their KD values. This effect was preserved when protein synthesis was abolished. In addition, SR121463B rescued eight mutant human V2Rs (hV2Rs, three are responsible for nephrogenic diabetes insipidus) characterized by amino acid exchanges at the C-terminal end of transmembrane helix TM I and TM VII. In contrast, mutants with amino acid exchanges at the interface of TM II and IV were not rescued by either antagonist. The mechanisms involved in successful rescue of cell surface delivery are explained in a three-dimensional homology model of the antagonist-bound hV2R.
Forschungsinstitut für Molekulare Pharmakologie, Campus Berlin Buch, Robert-Roessle-Str. 10, 13125 Berlin, Germany.
Stefan
S
Wüller
Burkhard
B
Wiesner
Anja
A
Löffler
Jens
J
Furkert
Gerd
G
Krause
Ricardo
R
Hermosilla
Michael
M
Schaefer
Ralf
R
Schülein
Walter
W
Rosenthal
Alexander
A
Oksche
D000595:Amino Acid Sequence; D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001692:Biological Transport; D019921:Biotinylation; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D007700:Kinetics; D007834:Lasers; D051379:Mice; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry*; D008969:Molecular Sequence Data; D009025:Morpholines / Q000494:pharmacology; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D017483:Receptors, Vasopressin / Q000737:chemistry* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013141:Spiro Compounds / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection
D065092:Antidiuretic Hormone Receptor Antagonists; C485182:Cyan Fluorescent Protein; D018832:Molecular Chaperones; D009025:Morpholines; D010455:Peptides; D017483:Receptors, Vasopressin; D011993:Recombinant Fusion Proteins; D013141:Spiro Compounds; D049452:Green Fluorescent Proteins; C103281:satavaptan