title: Degradation mechanism of a Golgi-retained distal renal tubular acidosis mutant of the kidney anion exchanger 1 in renal cells.
abstract: Distal renal tubular acidosis (dRTA) can be caused by mutations in the SLC4A1 gene encoding the anion exchanger 1 (AE1). Both recessive and dominant mutations result in mistrafficking of proteins, preventing them from reaching the basolateral membrane of renal epithelial cells, where their function is needed. In this study, we show that two dRTA mutants are prematurely degraded. Therefore, we investigated the degradation pathway of the kidney AE1 G701D mutant that is retained in the Golgi. Little is known about degradation of nonnative membrane proteins from the Golgi compartments in mammalian cells. We show that the kidney AE1 G701D mutant is polyubiquitylated and degraded by the lysosome and the proteosome. This mutant reaches the plasma membrane, where it is endocytosed and degraded by the lysosome via a mechanism dependent on the peripheral quality control machinery. Furthermore, we show that the function of the mutant is rescued at the cell surface upon inhibition of the lysosome and incubation with a chemical chaperone. We conclude that modulating the peripheral quality control machinery may provide a novel therapeutic option for treatment of patients with dRTA due to a Golgi-retained mutant.
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and.
authors.forename: Carmen Y
authors.initials: CY
authors.lastname: Chu
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and.
authors.forename: Jennifer
authors.initials: J
authors.lastname: King
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and.
authors.forename: Mattia
authors.initials: M
authors.lastname: Berrini
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and.
authors.forename: Alina C
authors.initials: AC
authors.lastname: Rumley
authors.affiliation: Department of Physiology, McGill University, Montreal, Quebec, Canada.
authors.forename: Pirjo M
authors.initials: PM
authors.lastname: Apaja
authors.affiliation: Department of Physiology, McGill University, Montreal, Quebec, Canada.
authors.forename: Gergely L
authors.initials: GL
authors.lastname: Lukacs
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and.
authors.forename: R Todd
authors.initials: RT
authors.lastname: Alexander
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Alberta, Canada; and cordat@ualberta.ca.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Cordat
mesh_terms: D000141:Acidosis, Renal Tubular / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004285:Dogs; D004705:Endocytosis / Q000502:physiology; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000502:physiology; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006056:Golgi Apparatus / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D008247:Lysosomes; D061985:Madin Darby Canine Kidney Cells; D009154:Mutation; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D059748:Proteolysis; D054875:Ubiquitination
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D056827:Endosomal Sorting Complexes Required for Transport; D011500:Protein Synthesis Inhibitors; C454201:SLC4A1 protein, human; D003513:Cycloheximide
keywords: Golgi; acidosis; bicarbonate; epithelium; kidney; lysosome; membrane protein; pH; proteosome; quality control; trafficking; transporters