title: Ras and Rap1 govern spatiotemporal dynamic of activated ERK in pituitary living cells.
abstract: The Ras/Raf/MEK/ERK is a conserved signalling pathway involved in the control of fundamental cellular processes. Despite extensive research, how this pathway can process a myriad of diverse extracellular inputs into substrate specificity to determine biological outcomes is not fully understood. It has been established that the ERK1/2 pathway is an integrative point in the control of the pituitary function exerted by various extracellular signals. In addition we previously established that the GTPases Ras and Rap1 play a key role in the regulation of ERK1/2-dependent prolactin transcription by EGF or the cAMP-dependent neuropeptide VIP. In this report, using the FRET-based biosensor of ERK activity (EKAR) in the pituitary GH4C1 cell line, we show that both EGF and VIP tightly control the spatiotemporal dynamic of activated ERK with different magnitude and duration. Importantly, we provide the first evidence of a differential control of cytoplasmic and nuclear pools of activated ERK by the GTPases Ras and Rap1. Ras is required for nuclear magnitude and duration of EGF-dependent ERK activation, whereas it is required for both VIP-activated cytoplasmic and nuclear ERK pools. Rap1 is exclusively involved in VIP-activated ERK nuclear pool. Moreover, consistent with the control of the nuclear pool of activated ERK by the GTPases, we observe the same differential role of Ras and Rap1 on ERK nuclear translocation triggered by EGF or VIP. Together these findings identify Ras and Rap1 as determinant partners in shaping nuclear and cytoplasmic ERK kinetics in response to EGF and VIP, which in turn should control pituitary secretion.
authors.affiliation: Aix-Marseille Université, CNRS, CRN2M UMR 7286, 13344 cedex 15, Marseille, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Zeiller
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Blanchard
authors.forename: Morgane
authors.initials: M
authors.lastname: Pertuit
authors.forename: Sylvie
authors.initials: S
authors.lastname: Thirion
authors.forename: Alain
authors.initials: A
authors.lastname: Enjalbert
authors.forename: Anne
authors.initials: A
authors.lastname: Barlier
authors.forename: Corinne
authors.initials: C
authors.lastname: Gerard
mesh_terms: D000818:Animals; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D031541:Fluorescence Resonance Energy Transfer; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism*
chemical_list: D014660:Vasoactive Intestinal Peptide; D004815:Epidermal Growth Factor; D011388:Prolactin; D000242:Cyclic AMP; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020827:rap1 GTP-Binding Proteins; D018631:ras Proteins