A retinoic acid receptor RARα pool present in membrane lipid rafts forms complexes with G protein αQ to activate p38MAPK

Oncogene. 2012 Jul 12;31(28):3333-45. doi: 10.1038/onc.2011.499. Epub 2011 Nov 7.

Abstract

Retinoic acid (RA) regulates several gene programs by nuclear RA receptors (RARs) that are ligand-dependent transcriptional transregulators. The basic mechanism for switching on transcription of cognate-target genes involves RAR binding at specific response elements and a network of interactions with coregulatory protein complexes. In addition to these classical genomic effects, we recently demonstrated that RA also induces the rapid activation of the p38MAPK/MSK1 pathway, with characteristic downstream consequences on the phosphorylation of RARs and the expression of their target genes. Here, we aimed at deciphering the underlying mechanism of the rapid non-genomic effects of RA. We highlighted a novel paradigm in which a fraction of the cellular RARα pool is present in membrane lipid rafts, where it forms complexes with G protein alpha Q (Gαq) in response to RA. This rapid RA-induced formation of RARα/Gαq complexes in lipid rafts is required for the activation of p38MAPK that occurs in response to RA. Accordingly, in RA-resistant cancer cells, characterized by the absence of p38MAPK activation, RARα present in membrane lipid rafts does not associate with Gαq, pointing out the essential contribution of RARα/Gαq complexes in RA signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Enzyme Activation / drug effects
  • GTP-Binding Protein alpha Subunits, Gq-G11 / metabolism*
  • Humans
  • Membrane Microdomains / drug effects
  • Membrane Microdomains / metabolism*
  • Protein Binding / drug effects
  • Protein Transport / drug effects
  • Receptor, ErbB-2 / metabolism
  • Receptors, Retinoic Acid / metabolism*
  • Retinoic Acid Receptor alpha
  • Signal Transduction / drug effects
  • Tretinoin / pharmacology
  • p38 Mitogen-Activated Protein Kinases / metabolism*

Substances

  • RARA protein, human
  • Receptors, Retinoic Acid
  • Retinoic Acid Receptor alpha
  • Tretinoin
  • Receptor, ErbB-2
  • p38 Mitogen-Activated Protein Kinases
  • GTP-Binding Protein alpha Subunits, Gq-G11