RESUMO
Degradation of damaged mitochondria by mitophagy is an essential process to ensure cell homeostasis. Because neurons, which have a high energy demand, are particularly dependent on the mitochondrial dynamics, mitophagy represents a key mechanism to ensure correct neuronal function. Collapsin response mediator proteins 5 (CRMP5) belongs to a family of cytosolic proteins involved in axon guidance and neurite outgrowth signaling during neural development. CRMP5, which is highly expressed during brain development, plays an important role in the regulation of neuronal polarity by inhibiting dendrite outgrowth at early developmental stages. Here, we demonstrated that CRMP5 was present in vivo in brain mitochondria and is targeted to the inner mitochondrial membrane. The mitochondrial localization of CRMP5 induced mitophagy. CRMP5 overexpression triggered a drastic change in mitochondrial morphology, increased the number of lysosomes and double membrane vesicles termed autophagosomes, and enhanced the occurrence of microtubule-associated protein 1 light chain 3 (LC3) at the mitochondrial level. Moreover, the lipidated form of LC3, LC3-II, which triggers autophagy by insertion into autophagosomes, enhanced mitophagy initiation. Lysosomal marker translocates at the mitochondrial level, suggesting autophagosome-lysosome fusion, and induced the reduction of mitochondrial content via lysosomal degradation. We show that during early developmental stages the strong expression of endogenous CRMP5, which inhibits dendrite growth, correlated with a decrease of mitochondrial content. In contrast, the knockdown or a decrease of CRMP5 expression at later stages enhanced mitochondrion numbers in cultured neurons, suggesting that CRMP5 modulated these numbers. Our study elucidates a novel regulatory mechanism that utilizes CRMP5-induced mitophagy to orchestrate proper dendrite outgrowth and neuronal function.
Assuntos
Amidoidrolases/metabolismo , Dendritos/metabolismo , Mitocôndrias/metabolismo , Mitofagia/fisiologia , Proteínas do Tecido Nervoso/metabolismo , Amidoidrolases/genética , Animais , Células COS , Chlorocebus aethiops , Dendritos/genética , Regulação da Expressão Gênica/fisiologia , Humanos , Hidrolases , Lisossomos/genética , Lisossomos/metabolismo , Camundongos , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Mitocôndrias/genética , Membranas Mitocondriais/metabolismo , Proteínas do Tecido Nervoso/genética , Fagossomos/genética , Fagossomos/patologiaRESUMO
The collapsin response-mediator proteins (CRMPs) are multifunctional proteins highly expressed during brain development but down-regulated in the adult brain. They are involved in axon guidance and neurite outgrowth signalling. Among these, the intensively studied CRMP2 has been identified as an important actor in axon outgrowth, this activity being correlated with the reorganisation of cytoskeletal proteins via the phosphorylation state of CRMP2. Another member, CRMP5, restricts the growth-promotional effects of CRMP2 by inhibiting dendrite outgrowth at early developmental stages. This inhibition occurs when CRMP5 binds to tubulin and the microtubule-associated protein MAP2, but the role of CRMP5 phosphorylation is still unknown. Here, we have studied the role of CRMP5 phosphorylation by mutational analysis. Using non-phosphorylatable truncated constructs of CRMP5 we have demonstrated that, among the four previously identified CRMP5 phosphorylation sites (T509, T514, T516 and S534), only the phosphorylation at T516 residue was needed for neurite outgrowth inhibition in PC12 cells and in cultured C57BL/6J mouse hippocampal neurons. Indeed, the expression of the CRMP5 non-phosphorylated form induced a loss of function of CRMP5 and the mutant mimicking the phosphorylated form induced the growth inhibition function seen in wildtype CRMP5. The T516 phosphorylation was achieved by the glycogen synthase kinase-3ß (GSK-3ß), which can phosphorylate the wildtype protein but not the non-phosphorylatable mutant. Furthermore, we have shown that T516 phosphorylation is essential for the tubulin-binding property of CRMP5. Therefore, CRMP5-induced growth inhibition is dependent on T516 phosphorylation through the GSK-3ß pathway. The findings provide new insights into the mechanisms underlying neurite outgrowth.
Assuntos
Dendritos/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neuritos/metabolismo , Neurônios/metabolismo , Animais , Células Cultivadas , Dendritos/fisiologia , Hipocampo/citologia , Hidrolases , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Associadas aos Microtúbulos , Neuritos/fisiologia , Neurônios/fisiologia , Células PC12 , Fosforilação , Ratos , Treonina/química , Tubulina (Proteína)/metabolismoRESUMO
Collapsin Response Mediator Protein 5 (CRMP5) belongs to a family of five cytosolic proteins highly expressed in the developing nervous system but downregulated in the adult brain. When expressed at the adult stage, CRMP5 is involved in neurological disorders. Indeed, CRMP5 is found expressed in cancer cells of some brain tumors, such as glioblastoma, or in small cell lung cancer causing paraneoplastic neurological syndromes as a result of cancer-induced auto-immune processes. Nevertheless, its role in cancer pathology is still obscure. Here, we show a new short isoform, derived from C-terminal processing of CRMP5, presenting a nuclear localization both in human glioblastoma, and in cancer cell lines (H69, GL15). By mutational analysis, we demonstrate that nuclear translocation occurs via nuclear localization signal (NLS), where the essential residue for nuclear location is K391. Direct CRMP5/ tubulin interaction, previously shown during brain development, does not occur for cytosolic CRMP5 in pathological conditions, leading to the suggestion that in cancer cells CRMP5 is not sequestered in the cytosol; therefore it may undergo C-terminal truncation allowing the exposure of the NLS for active translocation. Moreover, we show that the function associated with the CRMP5 nuclear targeting is an increase of cell proliferation activity.
Assuntos
Neoplasias Encefálicas/patologia , Núcleo Celular/metabolismo , Proliferação de Células , Replicação do DNA , Glioma/patologia , Proteínas do Tecido Nervoso/metabolismo , Sinais de Localização Nuclear/metabolismo , Animais , Apoptose , Western Blotting , Encéfalo/citologia , Encéfalo/metabolismo , Neoplasias Encefálicas/metabolismo , Células Cultivadas , Citosol/metabolismo , Citometria de Fluxo , Glioma/metabolismo , Humanos , Hidrolases , Técnicas Imunoenzimáticas , Imunoprecipitação , Proteínas Associadas aos Microtúbulos , Isoformas de Proteínas , Coelhos , Transplante Heterólogo , Tubulina (Proteína)/metabolismoRESUMO
Pituitary adenomas are currently classified by histological, immunocytochemical and numerous ultrastructural characteristics lacking unequivocal prognostic correlations. We investigated the prognostic value of a new clinicopathological classification with grades based on invasion and proliferation. This retrospective multicentric case-control study comprised 410 patients who had surgery for a pituitary tumour with long-term follow-up. Using pituitary magnetic resonance imaging for diagnosis of cavernous or sphenoid sinus invasion, immunocytochemistry, markers of the cell cycle (Ki-67, mitoses) and p53, tumours were classified according to size (micro, macro and giant), type (PRL, GH, FSH/LH, ACTH and TSH) and grade (grade 1a: non-invasive, 1b: non-invasive and proliferative, 2a: invasive, 2b: invasive and proliferative, and 3: metastatic). The association between patient status at 8-year follow-up and age, sex, and classification was evaluated by two multivariate analyses assessing disease- or recurrence/progression-free status. At 8 years after surgery, 195 patients were disease-free (controls) and 215 patients were not (cases). In 125 of the cases the tumours had recurred or progressed. Analyses of disease-free and recurrence/progression-free status revealed the significant prognostic value (p < 0.001; p < 0.05) of age, tumour type, and grade across all tumour types and for each tumour type. Invasive and proliferative tumours (grade 2b) had a poor prognosis with an increased probability of tumour persistence or progression of 25- or 12-fold, respectively, as compared to non-invasive tumours (grade 1a). This new, easy to use clinicopathological classification of pituitary endocrine tumours has demonstrated its prognostic worth by strongly predicting the probability of post-operative complete remission or tumour progression and so could help clinicians choose the best post-operative therapy.
Assuntos
Hipófise/patologia , Neoplasias Hipofisárias/classificação , Neoplasias Hipofisárias/patologia , Adolescente , Adulto , Fatores Etários , Idoso , Estudos de Casos e Controles , Intervalo Livre de Doença , Feminino , Humanos , Estudos Longitudinais , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Hipófise/ultraestrutura , Neoplasias Hipofisárias/cirurgia , Prognóstico , Recidiva , Estudos Retrospectivos , Sensibilidade e Especificidade , Fatores Sexuais , Adulto JovemRESUMO
Collapsin response mediator proteins (CRMPs) are involved in signaling of axon guidance and neurite outgrowth during neural development and regeneration. Among these, CRMP2 has been identified as an important actor in neuronal polarity and axon outgrowth, these activities being correlated with the reorganization of cytoskeletal proteins. In contrast, the function of CRMP5, expressed during brain development, remains obscure. Here, we find that, in contrast to CRMP2, CRMP5 inhibits tubulin polymerization and neurite outgrowth. Knockdown of CRMP5 expression by small interfering RNA confirms its inhibitory functions. CRMP5 forms a ternary complex with MAP2 and tubulin, the latter involving residues 475-522 of CRMP5, exposed at the molecule surface. Using different truncated CRMP5 constructs, we demonstrate that inhibition of neurite outgrowth by CRMP5 is mediated by tubulin binding. When both CRMP5 and CRMP2 are overexpressed, the inhibitory effect of CRMP5 abrogates neurite outgrowth promotion induced by CRMP2, suggesting that CRMP5 acts as a dominant signal. In cultured hippocampal neurons, CRMP5 shows no effect on axon growth, whereas it inhibits dendrite outgrowth and formation, at an early developmental stage, correlated with its strong expression in neurites. At later stages, when dendrites begin to extend, CRMP5 expression is absent. However, CRMP2 is constantly expressed. Overexpression of CRMP5 with CRMP2 inhibits CRMP2-induced outgrowth both on the axonal and dendritic levels. Deficiency of CRMP5 expression enhanced the CRMP2 effect. This antagonizing effect of CRMP5 is exerted through a tubulin-based mechanism. Thus, the CRMP5 binding to tubulin modulates CRMP2 regulation of neurite outgrowth and neuronal polarity during brain development.
Assuntos
Amidoidrolases/metabolismo , Encéfalo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neuritos/metabolismo , Neurônios/fisiologia , Tubulina (Proteína)/metabolismo , Amidoidrolases/deficiência , Animais , Animais Recém-Nascidos , Encéfalo/citologia , Encéfalo/embriologia , Encéfalo/crescimento & desenvolvimento , Células Cultivadas , Embrião de Mamíferos , Regulação da Expressão Gênica no Desenvolvimento/genética , Proteínas de Fluorescência Verde/genética , Hidrolases , Imunoprecipitação/métodos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Associadas aos Microtúbulos/metabolismo , Mutação/genética , Ligação Proteica , Estrutura Terciária de Proteína/fisiologia , Transfecção/métodosRESUMO
Although most pituitary tumors are benign, some are invasive or aggressive. In the absence of specific markers of malignancy, only tumors with metastases are considered malignant. To identify markers of invasion and aggressiveness, we focused on prolactin (PRL) tumors in the human and rat. Using radiology and histological methods, we classified 25 human PRL tumors into three groups (non-invasive, invasive, and aggressive-invasive) and compared them with a model of transplantable rat PRL tumors with benign and malignant lineages. Combining histological(mitoses and labeling for Ki-67, P53, pituitary transforming tumor gene (PTTG), and polysialic acid neural cell adhesion molecule) and transcriptomic (microarrays and q-RTPCR) methods with clinical data (post-surgical outcome with case-control statistical analysis), we found nine genes implicated in invasion (ADAMTS6, CRMP1, and DCAMKL3) proliferation (PTTG, ASK, CCNB1, AURKB, and CENPE), or pituitary differentiation (PITX1) showing differential expression in the three groups of tumors (P = 0.015 to 0.0001). A case-control analysis, comparing patients in remission (9 controls) and patients with persistent or recurrent tumors (14 cases) revealed that eight out of the nine genes were differentially up- or downregulated (P = 0.05 to 0.002), with only PTTG showing no correlation with clinical course (P = 0.258). These combined histological and transcriptomic analyses improve the pathological diagnosis of PRL tumors, indicating a reliable procedure for predicting tumor aggressiveness and recurrence potential. The similar gene profiles found between non-invasive human and benign rat tumors, as well as between aggressive-invasive human and malignant rat tumors provide new insights into malignancy in human pituitary tumors.
Assuntos
Biomarcadores Tumorais/isolamento & purificação , Proliferação de Células , Técnicas de Diagnóstico Molecular , Neoplasias Hipofisárias/genética , Neoplasias Hipofisárias/patologia , Prolactinoma/genética , Prolactinoma/patologia , Animais , Feminino , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Invasividade Neoplásica , Metástase Neoplásica , Análise de Sequência com Séries de Oligonucleotídeos , Neoplasias Hipofisárias/classificação , Neoplasias Hipofisárias/diagnóstico , Prognóstico , Prolactinoma/classificação , Prolactinoma/diagnóstico , Ratos , Ratos WistarRESUMO
Aggressive pituitary tumors are rare but difficult to manage, as there is no effective chemotherapy to restrict their growth and cause their shrinkage. Within these tumors, growth-promoting cascades, like the PI3K/mTOR pathway, appear to be activated. We tested the efficacy of two inhibitors of this pathway, NVP-BKM120 (Buparlisib; pan-PI3K) and NVP-BEZ235 (dual PI3K/mTOR), both in vitro on immortalized pituitary tumor cells (GH3) and on primary cell cultures of human pituitary tumors and in vivo on a rat model of prolactin (PRL) tumors (SMtTW3). In vitro, NVP-BEZ235 had a potent apoptotic and cytostatic effect that was characterized by decreased cyclin D/E and Cdk4/2 protein levels and subsequent accumulation of cells in G1 In vivo, the effect was transient, with a decrease in mitotic index and increase in apoptosis; long-term treatment had no significant inhibitory effect on tumor growth. In contrast, while NVP-BKM120 had little effect in vitro, it dramatically limited tumor growth in vivo Increased Akt phosphorylation observed only in the NVP-BEZ235-treated tumors may explain the differential response to the two inhibitors. Primary cell cultures of human PRL pituitary tumors responded to NVP-BEZ235 with reduced cell viability and decreased hormone secretion, whereas NVP-BKM120 had little effect. Altogether, these results show a potential for PI3K inhibitors in the management of aggressive pituitary tumors. Mol Cancer Ther; 15(6); 1261-70. ©2016 AACR.
Assuntos
Aminopiridinas/administração & dosagem , Imidazóis/administração & dosagem , Morfolinas/administração & dosagem , Neoplasias Hipofisárias/tratamento farmacológico , Prolactina/metabolismo , Quinolinas/administração & dosagem , Transdução de Sinais/efeitos dos fármacos , Aminopiridinas/farmacologia , Animais , Proteínas de Ciclo Celular/metabolismo , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Humanos , Imidazóis/farmacologia , Morfolinas/farmacologia , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação/efeitos dos fármacos , Neoplasias Hipofisárias/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Quinolinas/farmacologia , Ratos , Serina-Treonina Quinases TOR/metabolismo , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Integrative genomics approaches associating DNA structure and transcriptomic analysis should allow the identification of cascades of events relating to tumor aggressiveness. While different genome alterations have been identified in pituitary tumors, none have ever been correlated with the aggressiveness. This study focused on one subtype of pituitary tumor, the prolactin (PRL) pituitary tumors, to identify molecular events associated with the aggressive and malignant phenotypes. We combined a comparative genomic hybridization and transcriptomic analysis of 13 PRL tumors classified as nonaggressive or aggressive. Allelic loss within the p arm region of chromosome 11 was detected in five of the aggressive tumors. Allelic loss in the 11q arm was observed in three of these five tumors, all three of which were considered as malignant based on the occurrence of metastases. Comparison of genomic and transcriptomic data showed that allelic loss impacted upon the expression of genes located in the imbalanced region. Data filtering allowed us to highlight five deregulated genes (DGKZ, CD44, TSG101, GTF2H1, HTATIP2), within the missing 11p region, potentially responsible for triggering the aggressive and malignant phenotypes of PRL tumors. Our combined genomic and transcriptomic analysis underlines the importance of chromosome allelic loss in determining the aggressiveness and malignancy of tumors.
Assuntos
Aberrações Cromossômicas , Cromossomos Humanos Par 11 , Neoplasias Hipofisárias/genética , Prolactinoma/genética , Acetiltransferases/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Ciclo Celular/genética , Hibridização Genômica Comparativa , Proteínas de Ligação a DNA/genética , Diacilglicerol Quinase/genética , Diacilglicerol Quinase/metabolismo , Regulação para Baixo/genética , Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Feminino , Perfilação da Expressão Gênica/métodos , Predisposição Genética para Doença/genética , Humanos , Receptores de Hialuronatos/genética , Receptores de Hialuronatos/metabolismo , Masculino , Pessoa de Meia-Idade , Fosfoproteínas/genética , Transdução de Sinais/genética , Fator de Transcrição TFIIH , Fatores de Transcrição/genética , Fatores de Transcrição TFII/genéticaRESUMO
Predicting pituitary tumor behavior remains a challenge, since the prognostic value of identified pathological markers has not yet been evaluated. Genome-wide transcriptome analyses allow the identification of molecular markers to highlight global changes in gene expression and enable the discovery of signaling pathways within complex biological networks. While several transcriptome studies comparing normal with tumoral pituitary as a whole or with respect to subtype have given interesting data concerning pituitary pathogenesis, none have considered pituitary tumor prognosis. Only one study to date, focusing on the pathological classification and progression of prolactin tumors, has identified some molecular markers with diagnostic and prognostic value. We reviewed data in the literature on human pituitary tumor transcriptome and conducted a meta-analysis on the expression of genes involved in cell growth, proliferation and the cell cycle. Based on our expertise, we evaluate the interests and the limitations of using this approach with human pituitary tumors.
Assuntos
Biomarcadores Tumorais/genética , Perfilação da Expressão Gênica/métodos , Regulação Neoplásica da Expressão Gênica , Neoplasias Hipofisárias/genética , Biomarcadores Tumorais/análise , Proliferação de Células , Progressão da Doença , Genoma , Humanos , Análise de Sequência com Séries de Oligonucleotídeos , Hipófise/química , Hipófise/patologia , Hormônios Hipofisários/genética , Neoplasias Hipofisárias/metabolismo , Neoplasias Hipofisárias/patologiaRESUMO
OBJECTIVE: Silent corticotroph adenomas (SCAs) are rare pituitary tumours immunoreactive for ACTH, but without clinical evidence of Cushing's disease. We characterized SCAs based on clinical, hormonal and molecular data, and compared the characteristics of these tumours with those of macro (MCA)- and micro (mCA)-ACTH adenomas with Cushing's disease. METHODS: Fifty ACTH adenomas (14 SCAs, 15 MCAs and 21 mCAs) with complete corresponding clinical, radiological and biochemical data were selected. Histological corticotroph differentiation; immunostaining for ACTH, beta-endorphin and beta-LPH; and mRNA expression levels of TPIT, POMC, GRalpha, prohormone convertase 1/3 (PC1/3) and galectin-3 were compared in 21 representative tumours. RESULTS: Despite the absence of clinical hypercortisolism in patients with SCA, elevated plasma ACTH levels that were similar to those associated with mCA were observed. The cortisol/ACTH ratio was similar between SCA and MCA groups and lower than that found with mCA (P<0.05). This dissociation could be explained by lower expression of PC1/3 in SCA and MCA than in mCA (P<0.05). After an i.v. dexamethasone suppression test, ACTH levels were significantly higher in patients with MCA than in those with mCA (P<0.05). Cytological and immunocytochemical analyses as well as mRNA expression levels of TPIT, POMC and GRalpha confirmed corticotroph differentiation in both mCAs and MCAs and in half of the SCAs, with a strong correlation between TPIT and POMC mRNA expression levels in SCAs (R(2)=0.72; P<0.01) and in MCAs (R(2)=0.65; P<0.05). CONCLUSIONS: Despite the absence of hypercortisolism, SCAs exhibit histological, biochemical and molecular corticotroph differentiation. SCA and MCA show hormonal and molecular similarities differentiating them from mCA.
Assuntos
Adenoma Hipofisário Secretor de ACT/sangue , Adenoma Hipofisário Secretor de ACT/patologia , Hipersecreção Hipofisária de ACTH/sangue , Hipersecreção Hipofisária de ACTH/patologia , Adenoma Hipofisário Secretor de ACT/genética , Adenoma Hipofisário Secretor de ACT/urina , Hormônio Adrenocorticotrópico/sangue , Adulto , Feminino , Galectina 3/genética , Proteínas de Homeodomínio/genética , Humanos , Hidrocortisona/sangue , Hidrocortisona/urina , Ensaio Imunorradiométrico , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Hipersecreção Hipofisária de ACTH/genética , Hipersecreção Hipofisária de ACTH/urina , Pró-Opiomelanocortina/genética , Pró-Proteína Convertase 1/genética , Receptores de Glucocorticoides/genética , Proteínas com Domínio T/genética , Adulto JovemRESUMO
CONTEXT AND OBJECTIVE: Predicting pituitary tumor behavior remains a challenge. This multiparameter investigation aimed to identify markers for recurrence and progression in prolactin tumors. DESIGN: From a cohort of patients treated for prolactin tumors by surgery, we retrospectively studied clinical data, tumor characteristics, clinical outcome, and the expression of nine genes by quantitative RT-PCR. RESULTS: This study included 94 patients (62 females and 32 men), with long postoperative follow-up periods (mean, 138 +/- 46 months); 54.3% of patients had a macro or giant adenoma. Tumors were classified into three pathological groups based on their radiological and histological characteristics (noninvasive, 61; invasive, 22; and aggressive-invasive, 11). Immediately after surgery, 60 patients (63.8%) went into remission (prolactin level normalization). Persistently elevated prolactin levels (36.2%) were associated with increasing age, male sex, high preoperative prolactin levels, large tumor size on univariate analysis, and invasion and pathological classification on univariate and multivariate (P = 8 x 10(-10) and 3 x 10(-8)) analysis. During follow-up, 19 patients (20%) had tumors that recurred or progressed under dopamine agonist treatment. Invasion and pathological classification were associated with recurrence or progression on univariate analysis. Seven genes (ADAMTS6, CRMP1, PTTG, ASK, CCNB1, AURKB, and CENPE) were associated with tumor recurrence or progression and five of these (ADAMTS6, CRMP1, ASK, CCNB1, and CENPE) were associated with the pathological classification. CONCLUSION: This study identifies both the clinical and histological factors that relate to prolactin tumor recurrence or progression. Molecular markers give additional information for prognosis of such tumors. Altogether, our results could influence the management of patients with pituitary tumors.
Assuntos
Neoplasias Hipofisárias/genética , Neoplasias Hipofisárias/patologia , Prolactinoma/genética , Prolactinoma/patologia , Adolescente , Adulto , Idoso , DNA Complementar/biossíntese , DNA Complementar/genética , Progressão da Doença , Feminino , Seguimentos , Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica/patologia , Recidiva Local de Neoplasia/epidemiologia , Hormônios Hipofisários/genética , Neoplasias Hipofisárias/cirurgia , Prognóstico , Prolactinoma/cirurgia , RNA/biossíntese , RNA/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Adulto JovemRESUMO
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.