Rit mutants confirm role of MEK/ERK signaling in neuronal differentiation and reveal novel Par6 interaction

Biochim Biophys Acta. 2007 Dec;1773(12):1793-800. doi: 10.1016/j.bbamcr.2007.09.008. Epub 2007 Oct 9.

Abstract

Rit is a novel member of the Ras superfamily of small GTP-binding proteins that regulates signaling pathways controlling cellular fate determination. Constitutively activated mutants of Rit induce terminal differentiation of pheochromocytoma (PC6) cells resulting in a sympathetic neuron-like phenotype characterized by the development of highly-branched neurites. Rit signaling has been found to activate several downstream pathways including MEK/ERK, p38 MAPK, Ral-specific guanine nucleotide exchange factors (GEFs), and Rit associates with the Par6 cell polarity machinery. In this study, a series of Rit effector loop mutants was generated to test the importance of these cellular targets to Rit-mediated neuronal differentiation. We find that Rit-mediated neuritogenesis is dependent upon MEK/ERK MAP kinase signaling but independent of RalGEF activation. In addition, in vivo binding studies identified a novel mechanism of Par6 interaction, suggesting that the cell polarity machinery may serve to spatially restrict Rit signaling.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism*
  • Amino Acid Sequence
  • Animals
  • COS Cells
  • Cell Differentiation*
  • Chlorocebus aethiops
  • Enzyme Activation
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Genes, Dominant
  • Humans
  • MAP Kinase Signaling System*
  • Mitogen-Activated Protein Kinase Kinases / metabolism
  • Molecular Sequence Data
  • Mutant Proteins / metabolism*
  • Mutation / genetics
  • Neurites / enzymology
  • Neurons / cytology*
  • Neurons / enzymology*
  • Protein Binding
  • Protein Structure, Tertiary
  • Rats
  • ral Guanine Nucleotide Exchange Factor / metabolism
  • ras Proteins / chemistry
  • ras Proteins / metabolism*

Substances

  • Adaptor Proteins, Signal Transducing
  • Mutant Proteins
  • PARD6A protein, human
  • ral Guanine Nucleotide Exchange Factor
  • Extracellular Signal-Regulated MAP Kinases
  • Mitogen-Activated Protein Kinase Kinases
  • ras Proteins