title: Proteomic exploration of pancreatic islets in mice null for the alpha2A adrenergic receptor.
abstract: The present studies extend recent findings that mice null for the alpha(2A) adrenergic receptor (alpha(2A) AR KO mice) lack suppression of exogenous secretagogue-stimulated insulin secretion in response to alpha(2) AR agonists by evaluating the endogenous secretagogue, glucose, ex vivo, and providing in vivo data that baseline insulin levels are elevated and baseline glucose levels are decreased in alpha(2A) AR KO mice. These latter findings reveal that the alpha(2A) AR subtype regulates glucose-stimulated insulin release in response to endogenous catecholamines in vivo. The changes in alpha(2A) AR responsiveness and resultant changes in insulin/glucose homeostasis encouraged us to utilize proteomics strategies to identify possible alpha(2A) AR downstream signaling molecules or other resultant changes due to perturbation of alpha(2A) AR expression. Although agonist stimulation of islets from wild type (WT) mice did not significantly alter islet protein profiles, several proteins were enriched in islets from alpha(2A) AR KO mice when compared with those from WT mice, including an enzyme participating in insulin protein processing. The present studies document the important role of the alpha(2A) AR subtype in tonic suppression of insulin release in response to endogenous catecholamines as well as exogenous alpha(2) agonists and provide insights into pleiotropic changes that result from loss of alpha(2A) AR expression and tonic suppression of insulin release.
authors.affiliation: Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
authors.forename: Xinran
authors.initials: X
authors.lastname: Hu
authors.forename: David
authors.initials: D
authors.lastname: Friedman
authors.forename: Salisha
authors.initials: S
authors.lastname: Hill
authors.forename: Richard
authors.initials: R
authors.lastname: Caprioli
authors.forename: Wendell
authors.initials: W
authors.lastname: Nicholson
authors.forename: Alvin C
authors.initials: AC
authors.lastname: Powers
authors.forename: Lawrence
authors.initials: L
authors.lastname: Hunter
authors.forename: Lee E
authors.initials: LE
authors.lastname: Limbird
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001786:Blood Glucose / Q000378:metabolism; D000068438:Brimonidine Tartrate; D004247:DNA / Q000235:genetics; D005260:Female; D005947:Glucose / Q000494:pharmacology; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism; D040901:Proteomics; D011810:Quinoxalines / Q000494:pharmacology; D018341:Receptors, Adrenergic, alpha-2 / Q000172:deficiency* / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists; D001786:Blood Glucose; D007328:Insulin; D011506:Proteins; D011810:Quinoxalines; D018341:Receptors, Adrenergic, alpha-2; D000068438:Brimonidine Tartrate; D004247:DNA; D005947:Glucose