Integration of G protein signals by extracellular signal-regulated protein kinases in SK-N-MC neuroepithelioma cells

J Neurochem. 2005 Sep;94(5):1457-70. doi: 10.1111/j.1471-4159.2005.03304.x. Epub 2005 Jun 30.

Abstract

Mammalian cells often receive multiple extracellular stimuli under physiological conditions, and the various signaling inputs have to be integrated for the processing of complex biological responses. G protein-coupled receptors (GPCRs) are critical players in converting extracellular stimuli into intracellular signals. In this report, we examined the integration of different GPCR signals by mitogen-activated protein kinases (MAPKs) using the SK-N-MC human brain neuroepithelioma cells as a neuronal model. Stimulation of the Gi-coupled neuropeptide Y1 and Gq-coupled muscarinic M1 acetylcholine receptors, but not the Gs-coupled dopamine D1 receptor, led to the activation of extracellular signal-regulated kinase (ERK). All three receptors were also capable of stimulating c-Jun NH2-terminal kinases (JNK) and p38 MAPK. The Gi-mediated ERK activation was completely suppressed upon inhibition of Src tyrosine kinases by PP1, while the Gq-induced response was suppressed by both PP1 and the Ca2+ chelator, BAPTA-AM. In contrast, activations of JNK and p38 by Gs-, Gi-, and Gq-coupled receptors were sensitive to PP1 and BAPTA-AM pretreatments. Simultaneous stimulation of Gi- and Gq-coupled receptors resulted in the synergistic activation of ERK, but not JNK or p38 MAPK. The Gi/Gq-induced synergistic ERK activation was PTX-sensitive, and appeared to be a co-operative effect between Ca2+ and Src family tyrosine kinases. Enhanced ERK activation was associated with an increase in CREB phosphorylation, while the JNK and p38-responsive transcription factor ATF-2 was weakly enhanced upon Gi/Gq-induction. This report provides evidence that G protein signals can be integrated at the level of MAPK, resulting in differential effects on ERK, JNK and p38 MAPK in SK-N-MC cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenylyl Cyclases / metabolism
  • Brain Neoplasms / metabolism
  • Brain Neoplasms / pathology
  • Calcium Signaling
  • Carbachol / pharmacology
  • Cyclic AMP Response Element-Binding Protein
  • Drug Combinations
  • Drug Synergism
  • Enzyme Activation
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • GTP-Binding Proteins / metabolism*
  • Humans
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • MAP Kinase Kinase 1 / metabolism
  • MAP Kinase Kinase 2 / metabolism
  • Neuroectodermal Tumors, Primitive, Peripheral / metabolism
  • Neuroectodermal Tumors, Primitive, Peripheral / pathology
  • Neurons / metabolism*
  • Neuropeptide Y / pharmacology
  • Receptor, Muscarinic M1 / metabolism
  • Receptors, G-Protein-Coupled / metabolism
  • Receptors, Neuropeptide Y / metabolism
  • Signal Transduction*
  • Transcription Factors / metabolism
  • Tumor Cells, Cultured
  • Type C Phospholipases / metabolism
  • p38 Mitogen-Activated Protein Kinases / metabolism
  • src-Family Kinases / metabolism

Substances

  • CREB1 protein, human
  • Cyclic AMP Response Element-Binding Protein
  • Drug Combinations
  • Neuropeptide Y
  • Receptor, Muscarinic M1
  • Receptors, G-Protein-Coupled
  • Receptors, Neuropeptide Y
  • Transcription Factors
  • neuropeptide Y-Y1 receptor
  • Carbachol
  • MAP2K2 protein, human
  • src-Family Kinases
  • Extracellular Signal-Regulated MAP Kinases
  • JNK Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 1
  • MAP Kinase Kinase 2
  • MAP2K1 protein, human
  • Type C Phospholipases
  • GTP-Binding Proteins
  • Adenylyl Cyclases