LAMTOR2-mediated modulation of NGF/MAPK activation kinetics during differentiation of PC12 cells

PLoS One. 2014 Apr 21;9(4):e95863. doi: 10.1371/journal.pone.0095863. eCollection 2014.


LAMTOR2 (p14), a part of the larger LAMTOR/Ragulator complex, plays a crucial role in EGF-dependent activation of p42/44 mitogen-activated protein kinases (MAPK, ERK1/2). In this study, we investigated the role of LAMTOR2 in nerve growth factor (NGF)-mediated neuronal differentiation. Stimulation of PC12 (rat adrenal pheochromocytoma) cells with NGF is known to activate the MAPK. Pharmacological inhibition of MEK1 as well as siRNA-mediated knockdown of both p42 and p44 MAPK resulted in inhibition of neurite outgrowth. Contrary to expectations, siRNA-mediated knockdown of LAMTOR2 effectively augmented neurite formation and neurite length of PC12 cells. Ectopic expression of a siRNA-resistant LAMTOR2 ortholog reversed this phenotype back to wildtype levels, ruling out nonspecific off-target effects of this LAMTOR2 siRNA approach. Mechanistically, LAMTOR2 siRNA treatment significantly enhanced NGF-dependent MAPK activity, and this effect again was reversed upon expression of the siRNA-resistant LAMTOR2 ortholog. Studies of intracellular trafficking of the NGF receptor TrkA revealed a rapid colocalization with early endosomes, which was modulated by LAMTOR2 siRNA. Inhibition of LAMTOR2 and concomitant destabilization of the remaining members of the LAMTOR complex apparently leads to a faster release of the TrkA/MAPK signaling module and nuclear increase of activated MAPK. These results suggest a modulatory role of the MEK1 adapter protein LAMTOR2 in NGF-mediated MAPK activation required for induction of neurite outgrowth in PC12 cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Differentiation / physiology
  • Endosomes / metabolism
  • Kinetics
  • MAP Kinase Kinase 1 / genetics
  • MAP Kinase Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinases / genetics
  • Mitogen-Activated Protein Kinases / metabolism*
  • Nerve Growth Factor / genetics
  • Nerve Growth Factor / metabolism*
  • PC12 Cells
  • Proteins / genetics
  • Proteins / metabolism*
  • Rats
  • Reverse Transcriptase Polymerase Chain Reaction


  • LAMTOR2 protein, mouse
  • Proteins
  • Nerve Growth Factor
  • Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 1