Gonadotropin-releasing hormone-induced activation of diacylglycerol kinase-zeta and its association with active c-src

J Biol Chem. 2004 Mar 19;279(12):11906-16. doi: 10.1074/jbc.M310784200. Epub 2004 Jan 5.

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.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Cell Line
  • Cell Membrane / metabolism
  • DNA Primers
  • Diacylglycerol Kinase / chemistry
  • Diacylglycerol Kinase / metabolism*
  • Electrophoresis, Gel, Two-Dimensional
  • Enzyme Activation
  • Gonadotropin-Releasing Hormone / metabolism
  • Gonadotropin-Releasing Hormone / physiology*
  • Humans
  • Molecular Sequence Data
  • Protein Transport
  • Proto-Oncogene Proteins pp60(c-src) / metabolism*

Substances

  • DNA Primers
  • Gonadotropin-Releasing Hormone
  • Diacylglycerol Kinase
  • Proto-Oncogene Proteins pp60(c-src)