title: Gonadotropin-releasing hormone-induced activation of diacylglycerol kinase-zeta and its association with active c-src.
abstract: Gonadotropin-releasing hormone (GnRH)-induced receptor activation has been demonstrated to entrain a wide variety of signaling modalities. Most signaling pathways are concerned with the control of serine, threonine, or tyrosine-protein kinases, however, in the current article we demonstrate that in both a model cell line and in gonadotropes, GnRH additionally mediates the activation of lipid-directed kinases. We have shown that there is a functional connection between protein-tyrosine kinase modulation and lipid kinase activation. In HEK293 cells stably expressing the Type I mammalian GnRH receptor, we employed a proteomic approach to identify novel protein binding partners for GnRH-activated c-Src. Using matrix-assisted laser desorption ionization time-of-flight mass spectrometry we identified a GnRH-induced association between c-Src and the lipid kinase, diacylglycerol kinase-zeta (DGK-zeta). Using reciprocal co-immunoprecipitation we show that there is a significant elevation of the association between catalytically active c-Src with DGK-zeta in both HEK293 cells and murine gonadotrope LbetaT2 cells. Employing lipid kinase assays we have shown that the catalytic activity of DGK-zeta is significantly heightened in both HEK293 and LbetaT2 cells by GnRH. In addition, we demonstrate that the activation of DGK-zeta exerts a functional role in the murine gonadotrope LbetaT2 cell line. Elevated expression of DGK-zeta resulted in a shortening of the time scale of ERK activation in these cells suggesting a potential role of endogenous DGK-zeta in controlling the induction of LHbeta transcription by ERK1/2.
authors.affiliation: MRC Human Reproductive Sciences Unit, Edinburgh Royal Infirmary, The University of Edinburgh Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, Scotland, United Kingdom.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Davidson
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Pawson
authors.forename: Rakel
authors.initials: R
authors.lastname: López de Maturana
authors.forename: Sarah H
authors.initials: SH
authors.lastname: Freestone
authors.forename: Perdita
authors.initials: P
authors.lastname: Barran
authors.forename: Robert P
authors.initials: RP
authors.lastname: Millar
authors.forename: Stuart
authors.initials: S
authors.lastname: Maudsley
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D017931:DNA Primers; D019852:Diacylglycerol Kinase / Q000737:chemistry / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D004789:Enzyme Activation; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D021381:Protein Transport; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D007987:Gonadotropin-Releasing Hormone; D019852:Diacylglycerol Kinase; D016392:Proto-Oncogene Proteins pp60(c-src)