Identification of novel neuronal isoforms of the Rho-GEF Trio

Biol Cell. 2006 Mar;98(3):183-93. doi: 10.1042/BC20050009.


Background information: The large family of GEFs (guanine nucleotide-exchange factors) for Rho GTPases activate the GTPases by accelerating their GDP/GTP exchange. The multidomain protein Trio is the founding member of an intriguing subfamily of Rho-GEFs exhibiting two Rho-GEF and numerous additional domains. The members of the Trio family play an important role in neuronal physiology, and their structural organization is very well conserved through evolution. It has previously been shown that all the members, except mammalian Trio, display several isoforms, the functions of which have been well established.

Results: In this study, we have identified, by a combination of different approaches, novel Trio isoforms that have been generated by alternative splicing, giving rise to proteins that exhibit one or two Rho-GEF domains (GEFDs). These isoforms are specifically expressed in the nervous system, at a higher level than the full-length Trio, which is ubiquitously expressed. In addition, we show that all the GEFD1-containing isoforms induce neurite outgrowth in neuroblastoma cells.

Conclusions: We have identified neuronal specific isoforms of Trio which could be essential for Trio function in neuronal morphology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Cell Proliferation
  • DNA, Complementary / genetics
  • Guanine Nucleotide Exchange Factors / genetics
  • Guanine Nucleotide Exchange Factors / metabolism*
  • Humans
  • Mice
  • Mice, Inbred BALB C
  • Mice, Knockout
  • Neurons / metabolism*
  • PC12 Cells
  • Phosphoproteins / genetics*
  • Phosphoproteins / metabolism*
  • Protein Serine-Threonine Kinases / genetics*
  • Protein Serine-Threonine Kinases / metabolism*
  • Rats
  • Sequence Homology, Amino Acid
  • Signal Transduction
  • Transfection
  • rho GTP-Binding Proteins / metabolism*


  • DNA, Complementary
  • Guanine Nucleotide Exchange Factors
  • Phosphoproteins
  • Protein Serine-Threonine Kinases
  • TRIO protein, human
  • rho GTP-Binding Proteins