title: The 27-kDa heat shock protein confers cytoprotective effects through a beta 2-adrenergic receptor agonist-initiated complex with beta-arrestin.
abstract: Heat shock proteins represent an emerging model for the coordinated, multistep regulation of apoptotic signaling events. Although certain aspects of the biochemistry associated with heat shock protein cytoprotective effects are known, little information is found describing the regulation of heat shock protein responses to harmful stimuli. During screening for noncanonical beta adrenergic receptor signaling pathways in human urothelial cells, using mass spectroscopy techniques, an agonist-dependent interaction with beta-arrestin and the 27-kDa heat shock protein was observed in vitro. Formation of this beta-arrestin/Hsp27 complex in response to the selective beta adrenergic receptor agonist isoproterenol, was subsequently confirmed in situ by immunofluorescent colocalization studies. Radioligand binding techniques characterized a homogeneous population of the beta2 adrenergic receptor subtype expressed on these cells. Using terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling, immunoblot analysis and quantitation of caspase-3 activity to detect apoptosis, preincubation of these cells with isoproterenol was found to be sufficient for protection against programmed cell death initiated by staurosporine. RNA interference strategies confirmed the necessity for Hsp27 as well as both beta-arrestin isoforms to confer this cytoprotective consequence of beta adrenergic receptor activation in this cell model. As a result, these studies represent the first description of an agonist-dependent relationship between a small heat shock protein and beta-arrestin to form a previously unknown antiapoptotic "signalosome."
authors.affiliation: Department of Pharmacology, Physiology and Therapeutics, University of North Dakota, Grand Forks, ND 58202-9037, USA.
authors.forename: Lalida
authors.initials: L
authors.lastname: Rojanathammanee
authors.forename: Erin B
authors.initials: EB
authors.lastname: Harmon
authors.forename: Laurel A
authors.initials: LA
authors.lastname: Grisanti
authors.forename: Piyarat
authors.initials: P
authors.lastname: Govitrapong
authors.forename: Manuchair
authors.initials: M
authors.lastname: Ebadi
authors.forename: Bryon D
authors.initials: BD
authors.lastname: Grove
authors.forename: Masaru
authors.initials: M
authors.lastname: Miyagi
authors.forename: James E
authors.initials: JE
authors.lastname: Porter
mesh_terms: D058666:Adrenergic beta-2 Receptor Agonists; D000318:Adrenergic beta-Agonists / Q000378:metabolism* / Q000494:pharmacology; D000595:Amino Acid Sequence; D051017:Apoptosis Regulatory Proteins / Q000819:agonists / Q000502:physiology; D019390:Arrestins / Q000235:genetics / Q000502:physiology*; D002461:Cell Line, Transformed; D019610:Cytoprotection / Q000187:drug effects / Q000502:physiology*; D055551:HSP27 Heat-Shock Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D020033:Protein Isoforms / Q000819:agonists / Q000502:physiology; D034622:RNA Interference; D018343:Receptors, Adrenergic, beta-2 / Q000502:physiology*; D019459:Urothelium / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000071557:beta-Arrestins
chemical_list: D058666:Adrenergic beta-2 Receptor Agonists; D000318:Adrenergic beta-Agonists; D051017:Apoptosis Regulatory Proteins; D019390:Arrestins; D055551:HSP27 Heat-Shock Proteins; D020033:Protein Isoforms; D018343:Receptors, Adrenergic, beta-2; D000071557:beta-Arrestins