Mitogen activated-protein kinases (MAPKs) such as ERK and p38 play a
crucial role in synaptic plasticity since they are involved both in neuritogenesis and in neuronal polarity,
differentiation and survival (Howe et al. 2001, Krapivinski et al. 2003, Nakata et al. 2005). These MAPKs are
polarly localized in tip-growing neuronal axons. ERK, as an essential component, participates on signalling
induced by neuronal growth factor (NGF) during retrograde transport of NGF receptor from synapses to the cell
body, as well as on the signalling of glutamate receptors of the NMDA subtype underlying memory processes
(Howe et al. 2001, Krapivinski et al. 2003). Recently, a novel p38 MAPK pathway was shown to play a role in
pre-synaptic development (Nakata et al.2005). Interestingly, scaffolded molecular members of ERK pathway
including NGF recepror, TRK, RAS, RAF, MEK and ERK itself are associated with clathrin-coated vesicles and
with signalling endosomes upon NGF activation (Howe et al. 2001). On the other hand, hydrogen peroxide induces
p38 and accelerates endocytosis via stimulation of GDI:Rab5 complex (Cavalli et al. 2001). In plants, nothing
is known about the function of MAPK membrane scaffolding. Previously, we revealed that plant MAPK, polarly
localized to vesicular structures, is associated with tip-growth of root hairs (Šamaj et al. 2002). Our
recent data suggest that MAPKs are enriched at transversal cross walls of root cell files (representing
putative plant synapses), and some MAPKs are subcelularly targeted to clathrin-coated vesicles and endosomal
membranes, a phenomenon which is enhanced by oxidative and other abiotic stresses.
- Cavalli V, Vilbois F, Corti M, Marcote MJ, Tamura K, Karin M, Arkinstall S, Gruenberg J (2001) The
stress-induced MAP kinase p38 regulates endocytic trafficking via GDI:Rab5 complex. Mol Cell 7: 421-432
- Howe CL, Valletta JS, Rusnak AS, Mobley WC (2001) NGF signalling from clathrin-coated
vesicles: evidence that signaling endosomes serve as a platform for the Ras-MAPK pathway. Neuron 32: 801-814
- Krapivinski G, Krapivinski L, Manasian Y, Ivanov A, Tyzio R, Pellegrino C, Ben-Ari Y,
Clapham DE, Medina I (2003) The NMDA receptor is coupled to the ERK pathway by a direct interaction between
NRB2B and RasGRF1. neuron 40: 775-784
- Nakata K, Abrams B, Grill B, Goncharov A, Huang X,
Chisholm AD, Jin Y (2005) Regulation of a DLK-1 and p38 MAP kinase pathway by the ubiquitin ligase RPM-1 is
required for presynaptic development. Cell 120: 407-420
- Šamaj J, Ovecka M,
Hlavacka A, Lecourieux F, Meskiene I, Lichtscheidl I, Lenart P, Salaj J, Volkmann D, Bogre L, Baluška
F, Hirt H (2002) Involvement of the mitogen-activated protein kinase SIMK in regulation of root hair tip
growth. EMBO J 21: 3296-3306
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