MONENSIN-RESISTANT LLC-PK1 CELL MUTANTS ARE AFFECTED IN RECYCLING OF THE ADENYLATE CYCLASE-STIMULATING VASOPRESSIN V2-RECEPTOR

[摘要] 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 [H-3]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 monensin 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.

[发布日期] 1991-10-01

[关键词] ENDOCYTOSIS;MONENSIN;RECEPTOR RECYCLING;RENAL EPITHELIAL CELL MUTANT