title: Multi-component signaling complexes of the delta-opioid receptor with STAT5B and G proteins.
abstract: Besides mediating opioid responses in the nervous system and the peripheral tissues, opioid receptors are implicated in signaling mechanisms shared by cytokine receptors. Recent observations have shown that the Signal Transducer and Activator of Transcription 5A (STAT5A) interacts with the mu-opioid receptor (mu-OR) and is phosphorylated upon mu-OR stimulation (Mazarakou and Georgoussi, 2005). In the present study we demonstrate that another member of the STAT family, STAT5B, associates constitutively with the C-terminal tail of the delta-opioid receptor (delta-CT). [D-Ser(2), Leu(5), Thr(6)]-enkephalin-exposure of HEK293 cells, expressing stably the delta-opioid receptor (delta-OR), leads to receptor-dependent STAT5B tyrosine phosphorylation and transcriptional activation. This phosphorylation occurs in a G protein-dependent manner and is carried out by a c-Src kinase. Co-immunoprecipitation studies indicate that STAT5B forms pairs with selective Galpha and Gbetagamma subunits of G proteins and activated c-Src kinase in HEK293 cells. These interactions are formed either constitutively, or upon receptor stimulation. We also demonstrate that the delta-CT serves as a platform for the formation of a multi-component signaling complex (signalosome), consisting of STAT5B, c-Src and selective G protein members. We can thus conclude that STAT5B signaling can be modulated by its coupling with a specific subset of G protein subunits, revealing a novel signaling mechanism for the transcriptional regulation of STAT5B-dependent genes.
authors.affiliation: Laboratory of Cellular Signaling and Molecular Pharmacology, Institute of Biology, National Centre for Scientific Research Demokritos, 15310 Ag. Paraskevi-Attikis, Athens, Greece.
authors.forename: Eirini-Maria
authors.initials: EM
authors.lastname: Georganta
authors.forename: Adamantia
authors.initials: A
authors.lastname: Agalou
authors.forename: Zafiroula
authors.initials: Z
authors.lastname: Georgoussi
mesh_terms: D000595:Amino Acid Sequence; D000701:Analgesics, Opioid / Q000494:pharmacology; D002461:Cell Line, Transformed; D017124:Conserved Sequence; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D009020:Morphine / Q000494:pharmacology; D009154:Mutation / Q000502:physiology; D037342:Pertussis Toxin / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D017465:Receptors, Opioid, delta / Q000235:genetics / Q000502:physiology*; D050799:STAT5 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014162:Transfection / Q000379:methods; D014443:Tyrosine / Q000378:metabolism
chemical_list: C108123:4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine; D000701:Analgesics, Opioid; D004791:Enzyme Inhibitors; D021122:Protein Subunits; D011720:Pyrazoles; D011743:Pyrimidines; D017465:Receptors, Opioid, delta; D050799:STAT5 Transcription Factor; C494095:STAT5B protein, human; D014443:Tyrosine; D004743:Enkephalin, Leucine; C034318:enkephalin, Ser(2), Leu(5), Thr(6)-; D009020:Morphine; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins