title: Transient hypoxia induces sequestration of M1 and M2 muscarinic acetylcholine receptors.
abstract: Oxidative stress has been implicated in impairing muscarinic acetylcholine receptor (mAChR) signaling activity. It remains unclear, however, whether alterations in the cell surface distribution of mAChRs following oxidative stress contribute to the diminished mAChR signaling activity. We report here that M1 and M2 mAChRs, stably expressed in Chinese hamster ovary cells, undergo sequestration following transient hypoxic-induced oxidative stress (2% O2). Sequestration of M1 and M2 mAChRs following transient hypoxia was associated with an increase in phosphorylation of these receptors. Over-expression of a catalytically inactive G protein-coupled receptor kinase 2 (GRK2 K220R) blocked the increased phosphorylation and sequestration of the M2, but not M1, mAChRs following transient hypoxia. Hypoxia induced phosphorylation and sequestration of the M1 mAChR was, however, blocked by over-expression of a catalytically inactive casein kinase 1 alpha (CK1alpha K46R). These results are the first demonstration that M1 and M2 mAChRs undergo sequestration following transient hypoxia. The data suggest that increased phosphorylation of M1 and M2 mAChRs underlies the mechanism responsible for sequestration of these receptors following transient hypoxia. We report here that distinct pathways involving CK1alpha and GRK2 mediated sequestration of M1 and M2 mAChRs following transient hypoxic-induced oxidative stress.
authors.affiliation: Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana 59812, USA.
authors.forename: Liping
authors.initials: L
authors.lastname: Mou
authors.forename: Alicia
authors.initials: A
authors.lastname: Gates
authors.forename: Valerie A
authors.initials: VA
authors.lastname: Mosser
authors.forename: Andrew
authors.initials: A
authors.lastname: Tobin
authors.forename: Darrell A
authors.initials: DA
authors.lastname: Jackson
mesh_terms: D000818:Animals; D016466:CHO Cells; D047389:Casein Kinase I / Q000378:metabolism; D016923:Cell Death; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D008024:Ligands; D018384:Oxidative Stress; D010766:Phosphorylation; D011506:Proteins / Q000378:metabolism; D043643:Receptor, Muscarinic M1 / Q000235:genetics / Q000378:metabolism*; D043585:Receptor, Muscarinic M2 / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D051552:beta-Adrenergic Receptor Kinases / Q000378:metabolism
chemical_list: D008024:Ligands; D011506:Proteins; D043643:Receptor, Muscarinic M1; D043585:Receptor, Muscarinic M2; D047389:Casein Kinase I; D051552:beta-Adrenergic Receptor Kinases