title: Pancreatic β-cell prosurvival effects of the incretin hormones involve post-translational modification of Kv2.1 delayed rectifier channels.
abstract: Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are the major incretin hormones that exert insulinotropic and anti-apoptotic actions on pancreatic β-cells. Insulinotropic actions of the incretins involve modulation of voltage-gated potassium (Kv) channels. In multiple cell types, Kv channel activity has been implicated in cell volume changes accompanying initiation of the apoptotic program. Focusing on Kv2.1, we examined whether regulation of Kv channels in β-cells contributes to the prosurvival effects of incretins. Overexpression of Kv2.1 in INS-1 β-cells potentiated apoptosis in response to mitochondrial and ER stress and, conversely, co-stimulation with GIP/GLP-1 uncoupled this potentiation, suppressing apoptosis. In parallel, incretins promoted phosphorylation and acetylation of Kv2.1 via pathways involving protein kinase A (PKA)/mitogen- and stress-activated kinase-1 (MSK-1) and histone acetyltransferase (HAT)/histone deacetylase (HDAC). Further studies demonstrated that acetylation of Kv2.1 was mediated by incretin actions on nuclear/cytoplasmic shuttling of CREB binding protein (CBP) and its interaction with Kv2.1. Regulation of β-cell survival by GIP and GLP-1 therefore involves post-translational modifications (PTMs) of Kv channels by PKA/MSK-1 and HAT/HDAC. This appears to be the first demonstration of modulation of delayed rectifier Kv channels contributing to the β-cell prosurvival effects of incretins and of 7-transmembrane G protein-coupled receptor (GPCR)-stimulated export of a nuclear lysine acetyltransferase that regulates cell surface ion channel function.
authors.affiliation: Departments of Cellular & Physiological Sciences and the Diabetes Research Group, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada.
authors.forename: S-J
authors.initials: SJ
authors.lastname: Kim
authors.forename: S B
authors.initials: SB
authors.lastname: Widenmaier
authors.forename: W S
authors.initials: WS
authors.lastname: Choi
authors.forename: C
authors.initials: C
authors.lastname: Nian
authors.forename: Z
authors.initials: Z
authors.lastname: Ao
authors.forename: G
authors.initials: G
authors.lastname: Warnock
authors.forename: C H S
authors.initials: CH
authors.lastname: McIntosh
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000328:Adult; D017209:Apoptosis / Q000187:drug effects; D050882:CREB-Binding Protein / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D005749:Gastric Inhibitory Polypeptide / Q000494:pharmacology; D052216:Glucagon-Like Peptide 1 / Q000494:pharmacology; D051548:Histone Acetyltransferases / Q000378:metabolism; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D054795:Incretins / Q000494:pharmacology*; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D021381:Protein Transport / Q000187:drug effects; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000378:metabolism; D051669:Shab Potassium Channels / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D054795:Incretins; D051669:Shab Potassium Channels; D005749:Gastric Inhibitory Polypeptide; D019284:Thapsigargin; D052216:Glucagon-Like Peptide 1; D050882:CREB-Binding Protein; D051548:Histone Acetyltransferases; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C116919:mitogen and stress-activated protein kinase 1; D017868:Cyclic AMP-Dependent Protein Kinases; D006655:Histone Deacetylases; D019311:Staurosporine