title: ERK and RSK are necessary for TRH-induced inhibition of r-ERG potassium currents in rat pituitary GH3 cells.
abstract: The transduction pathway mediating the inhibitory effect that TRH exerts on r-ERG channels has been thoroughly studied in GH3 rat pituitary cells but some elements have yet to be discovered, including those involved in a phosphorylation event(s). Using a quantitative phosphoproteomic approach we studied the changes in phosphorylation caused by treatment with 1μM TRH for 5min in GH3 cells. The activating residues of Erk2 and Erk1 undergo phosphorylation increases of 5.26 and 4.87 fold, respectively, in agreement with previous reports of ERK activation by TRH in GH3 cells. Thus, we studied the possible involvement of ERK pathway in the signal transduction from TRH receptor to r-ERG channels. The MEK inhibitor U0126 at 0.5μM caused no major blockade of the basal r-ERG current, but impaired the TRH inhibitory effect on r-ERG. Indeed, the TRH effect on r-ERG was also reduced when GH3 cells were transfected with siRNAs against either Erk1 or Erk2. Using antibodies, we found that TRH treatment also causes activating phosphorylation of Rsk. The TRH effect on r-ERG current was also impaired when cells were transfected with any of two different siRNAs mixtures against Rsk1. However, treatment of GH3 cells with 20nM EGF for 5min, which causes ERK and RSK activation, had no effect on the r-ERG currents. Therefore, we conclude that in the native GH3 cell system, ERK and RSK are involved in the pathway linking TRH receptor to r-ERG channel inhibition, but additional components must participate to cause such inhibition.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Edificio Santiago Gascón, Campus de El Cristo, Universidad de Oviedo, 33006 Oviedo, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Carretero
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Edificio Santiago Gascón, Campus de El Cristo, Universidad de Oviedo, 33006 Oviedo, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Llavona
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Edificio Santiago Gascón, Campus de El Cristo, Universidad de Oviedo, 33006 Oviedo, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: López-Hernández
authors.affiliation: Integrative Cell Signalling and Proteomics, Centre for Haemato-Oncology, Barts Cancer Institute, Queen Mary University of London, Barts School of Medicine and Dentistry, London EC1M 6BQ, United Kingdom.
authors.forename: Pedro
authors.initials: P
authors.lastname: Casado
authors.affiliation: Integrative Cell Signalling and Proteomics, Centre for Haemato-Oncology, Barts Cancer Institute, Queen Mary University of London, Barts School of Medicine and Dentistry, London EC1M 6BQ, United Kingdom.
authors.forename: Pedro R
authors.initials: PR
authors.lastname: Cutillas
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Edificio Santiago Gascón, Campus de El Cristo, Universidad de Oviedo, 33006 Oviedo, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: de la Peña
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Edificio Santiago Gascón, Campus de El Cristo, Universidad de Oviedo, 33006 Oviedo, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Barros
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Edificio Santiago Gascón, Campus de El Cristo, Universidad de Oviedo, 33006 Oviedo, Spain. Electronic address: pdluengo@uniovi.es.
authors.forename: Pedro
authors.initials: P
authors.lastname: Domínguez
mesh_terms: D000818:Animals; D002460:Cell Line; D051638:Ether-A-Go-Go Potassium Channels / Q000235:genetics / Q000378:metabolism*; D017136:Ion Transport / Q000187:drug effects / Q000502:physiology; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000502:physiology; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D018025:Receptors, Thyrotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000235:genetics / Q000378:metabolism*; D052683:Somatotrophs / Q000166:cytology / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism
chemical_list: D051638:Ether-A-Go-Go Potassium Channels; D018025:Receptors, Thyrotropin-Releasing Hormone; D013973:Thyrotropin-Releasing Hormone; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D048052:Mitogen-Activated Protein Kinase 3
keywords: ERK (extracellular-signal-regulated kinase); Kv (voltage-gated potassium channels); Phosphoproteomics; Phosphorylation; RSK (ribosomal S6 kinase); Thyrotropin-releasing hormone