Processing and nuclear localization of CRMP2 during brain development induce neurite outgrowth inhibition
Processing and nuclear localization of CRMP2 during brain development induce neurite outgrowth inhibition
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DOI：
10.1074/jbc.m708480200
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发表时间：
2008-05-23
影响因子：
4.8
通讯作者：
Moradi-Ameli, Mahnaz
中科院分区：
文献类型：
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作者：
Rogemond, Veronique;Auger, Carole;Moradi-Ameli, Mahnaz
塌陷反应中介蛋白（CRMPs）在神经元分化和轴突生长中起着至关重要的作用。其中，CRMP2在发育过程中通过生长锥塌陷介导轴突引导。这种活性与细胞骨架蛋白的重组有关。CRMP2参与多种细胞内信号通路的调控。CRMP2B的两个亚型，A和B，以及多个胞质亚型，其表观质量在62至66 kDa之间。在这里，我们展示了一个新的58 kDa短异构体，在大脑发育过程中表达，来源于CRMP2B亚型的c端加工。虽然全长CRMP2局限于细胞质，但通过转染实验，我们证明了在细胞核中发现了部分短同种异构体。有趣的是，在组织水平上，这种短的CRMP2也存在于脑提取物的核部分中。通过突变分析，我们首次证明了核易位是通过CRMP2序列中Arg(471)-Lys（472）残基的核定位信号（NLS）发生的。经过c端处理后，NLS可以被揭开；因此，该基序可以表面暴露。这种短的CRMP2在神经母细胞瘤细胞中诱导神经突生长抑制，并抑制培养皮层神经元的轴突生长，而全长CRMP2促进神经突伸长。nls突变的短同种异构体，限制在细胞质中，消除了神经突的生长和轴突的生长抑制，表明短核CRMP2作为显性信号。因此，CRMP2的转录后加工及其核定位可能是调控脑发育中神经突生长的重要关键。
Collapsin response mediator proteins (CRMPs) 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 and 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 the CRMP2B subtype. Although 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 Arg(471)-Lys(472) 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, whereas 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.