title: Monensin-resistant LLC-PK1 cell mutants are affected in recycling of the adenylate cyclase-stimulating vasopressin V2-receptor.
abstract: The ionophore monensin was found to markedly reduce the rate of return of vasopressin V2-receptors to the membrane following down-regulation with [Arg8]vasopressin (AVP), as well as hormone dissociation (unloading) from cells following ligand binding and internalization in LLC-PK1 renal epithelial cells. Monensin-resistant LLC-PK1 mutants were isolated and characterized for V2-receptor recycling. Whilst the MN-41 mutant appeared to be impaired in [3H]AVP internalization, the MN-11 and MN-21 mutants exhibited parental V2-receptor binding and internalization, but markedly impaired receptor recycling subsequent to ligand-dependent receptor down-regulation. Unloading subsequent to ligand binding and internalization at 37 degrees C was also much slower in the mutants either at 37 degrees C or 23 degrees C. In contrast, unloading subsequent to binding at 23 degrees C, or to binding at 37 degrees C in the presence of NH4Cl, was comparable in LLC-PK1 and mutant cells implying the active nature of the recycling process impaired in the mutants. The mutations conferring resistance to monesin thus concomitantly impaired V2-receptor recycling in the mutants. Results argue for a monensin-sensitive endosomal/lysosomal pathway for the renal V2-receptor, representing the first such report for an adenylate cyclase stimulating receptor.
authors.affiliation: Max-Planck-Institut für Biophysik, Frankfurt, F.R.G.
authors.forename: D A
authors.initials: DA
authors.lastname: Jans
authors.forename: P
authors.initials: P
authors.lastname: Jans
authors.forename: H
authors.initials: H
authors.lastname: Luzius
authors.forename: F
authors.initials: F
authors.lastname: Fahrenholz
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism*; D001692:Biological Transport; D002460:Cell Line; D006224:Cricetinae; D015536:Down-Regulation; D004351:Drug Resistance / Q000235:genetics*; D004705:Endocytosis / Q000502:physiology; D008024:Ligands; D051379:Mice; D008985:Monensin / Q000494:pharmacology*; D009154:Mutation; D011945:Receptors, Angiotensin / Q000378:metabolism*; D017483:Receptors, Vasopressin
chemical_list: D008024:Ligands; D011945:Receptors, Angiotensin; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D008985:Monensin; D000262:Adenylyl Cyclases