Processing and nuclear localization of CRMP2 during brain development induce neurite outgrowth inhibition

Authors:
Rogemond V, Auger C, Giraudon P, Becchi M, Auvergnon N, Belin MF, Honnorat J, Moradi-Améli M
In:
Source: J Biol Chem
Publication Date: (2008)
Issue: 283(21): 14751-61
Research Area:
Neurobiology
Cells used in publication:
PC-12
Species: rat
Tissue Origin: adrenal
Platform:
Nucleofectorâ„¢ I/II/2b
Abstract
Collapsin response mediator proteins (CRMP) are believed to play a crucial role in neuronal differentiation and axonal outgrowth. Among them, CRMP2 mediates axonal guidance by collapsing growth cones during development. This activity is correlated with the reorganization of cytoskeletal proteins. CRMP2 is implicated in the regulation of several intracellular signaling pathways. Two subtypes A and B, and multiple cytosolic isoforms of CRMP2B with apparent masses between 62-66 kDa have previously been reported. Here, we show a new short isoform of 58 kDa, expressed during brain development, derived from C-terminal processing of CRMP2B subtype. While full-length CRMP2 is restricted to the cytoplasm, using transfection experiments, we demonstrate that a part of the short isoform is found in the nucleus. Interestingly, at the tissue level, this short CRMP2 is also found in a nuclear fraction of brain extract. By mutational analysis we demonstrate, for the first time, that nuclear translocation occurs via nuclear localization signal (NLS) within residues R471-K472 in CRMP2 sequence. The NLS may be unmasked after C-terminal processing, thereby, this motif may be surface-exposed. This short CRMP2 induces neurite outgrowth inhibition in neuroblastoma cells, and suppressed axonal growth in cultured cortical neurons, while full-length CRMP2 promotes neurite elongation. The NLS-mutated short isoform, restricted to the cytoplasm, abrogates both neurite outgrowth and axon growth inhibition, indicating that short nuclear CRMP2 acts as a dominant signal. Therefore, post-transcriptional processing of CRMP2 together with its nuclear localization may be an important key in the regulation of neurite outgrowth in brain development.