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Nf2/Merlin controls spinal cord neural progenitor function in a Rac1/ErbB2-dependent manner.

Garcia C, Gutmann DH - PLoS ONE (2014)

Bottom Line: We demonstrate that the Nf2 protein, merlin, negatively regulates spinal neural progenitor cell survival and glial differentiation in an ErbB2-dependent manner, and that NF2-associated spinal ependymomas exhibit increased ErbB2 activation.Moreover, we show that Nf2-deficient SC NPC ErbB2 activation results from Rac1-mediated ErbB2 retention at the plasma membrane.Collectively, these findings establish ErbB2 as a potential rational therapeutic target for NF2-associated spinal ependymoma.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, United States of America.

ABSTRACT

Objective: Individuals with the neurofibromatosis type 2 (NF2) cancer predisposition syndrome develop spinal cord glial tumors (ependymomas) that likely originate from neural progenitor cells. Whereas many spinal ependymomas exhibit indolent behavior, the only treatment option for clinically symptomatic tumors is surgery. In this regard, medical therapies are unfortunately lacking due to an incomplete understanding of the critical growth control pathways that govern the function of spinal cord (SC) neural progenitor cells (NPCs).

Methods: To identify potential therapeutic targets for these tumors, we leveraged primary mouse Nf2-deficient spinal cord neural progenitor cells.

Results: We demonstrate that the Nf2 protein, merlin, negatively regulates spinal neural progenitor cell survival and glial differentiation in an ErbB2-dependent manner, and that NF2-associated spinal ependymomas exhibit increased ErbB2 activation. Moreover, we show that Nf2-deficient SC NPC ErbB2 activation results from Rac1-mediated ErbB2 retention at the plasma membrane.

Significance: Collectively, these findings establish ErbB2 as a potential rational therapeutic target for NF2-associated spinal ependymoma.

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Related in: MedlinePlus

Wild-type, but not mutant, merlin re-expression restores SC NPC properties to WT levels.(A) Re-expression of WT (MSCV.NF2), but not mutant (MSCV.NF2.L64P), merlin reduced (B) SC NPC growth (diameter) and clonogenic expansion (neurospheres) to WT levels (diameters: MSCV, p<0.001; L64P, p<0.001; hNf2, p = 0.1584; average number of neurospheres: MSCV, p<0.0421; L64P, p<0.05; hNf2, p = 0.7138; two-way ANOVA with Bonferroni post-test). (C) Wild-type (WT; MSCV.NF2), but not mutant (MSCV.NF2.L64P), merlin expression in Nf2−/− SC NPCs decreases cell number at day 8 (MSCV, p<0.001; L64P, p<0.05; hNf2, p = 0.200; two-way ANOVA with Bonferroni post-test) and (D) glial differentiation to WT levels (MSCV, p<0.001; L64P, p<0.001; hNf2, p = 0.7238; two-way ANOVA with Bonferroni post-test). Wild-type (WT; MSCV.NF2), but not mutant (MSCV.NF2.L64P), merlin expression in Nf2−/− NPCs increases (E) neuronal (MSCV, p<0.001; L64P, p<0.001; hNf2- p = 0.1797; two-way ANOVA with Bonferroni post-test) and (F) oligodendrocyte differentiation to WT levels (MSCV, p<0.01; L64P, p<0.01; hNf2, p = 0.7308; two-way ANOVA with Bonferroni post-test. The data were normalized to the field of view. Values denote the mean ± SEM. (*) p<0.05; (**) p<0.001; (***) p<0.0001.
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pone-0097320-g002: Wild-type, but not mutant, merlin re-expression restores SC NPC properties to WT levels.(A) Re-expression of WT (MSCV.NF2), but not mutant (MSCV.NF2.L64P), merlin reduced (B) SC NPC growth (diameter) and clonogenic expansion (neurospheres) to WT levels (diameters: MSCV, p<0.001; L64P, p<0.001; hNf2, p = 0.1584; average number of neurospheres: MSCV, p<0.0421; L64P, p<0.05; hNf2, p = 0.7138; two-way ANOVA with Bonferroni post-test). (C) Wild-type (WT; MSCV.NF2), but not mutant (MSCV.NF2.L64P), merlin expression in Nf2−/− SC NPCs decreases cell number at day 8 (MSCV, p<0.001; L64P, p<0.05; hNf2, p = 0.200; two-way ANOVA with Bonferroni post-test) and (D) glial differentiation to WT levels (MSCV, p<0.001; L64P, p<0.001; hNf2, p = 0.7238; two-way ANOVA with Bonferroni post-test). Wild-type (WT; MSCV.NF2), but not mutant (MSCV.NF2.L64P), merlin expression in Nf2−/− NPCs increases (E) neuronal (MSCV, p<0.001; L64P, p<0.001; hNf2- p = 0.1797; two-way ANOVA with Bonferroni post-test) and (F) oligodendrocyte differentiation to WT levels (MSCV, p<0.01; L64P, p<0.01; hNf2, p = 0.7308; two-way ANOVA with Bonferroni post-test. The data were normalized to the field of view. Values denote the mean ± SEM. (*) p<0.05; (**) p<0.001; (***) p<0.0001.

Mentions: To establish a causal relationship between merlin loss and SC NPC function, merlin was re-expressed in Nf2-deficient NPCs by retroviral infection (Fig. 2A). In these experiments, expression of WT, but not NF2-patient mutant (L64P; [20], [21]), merlin restored SC NPC neurosphere diameters (Fig. 2B), clonogenic expansion (Fig. 2B), cell number (Fig. 2C), and multi-lineage differentiation (Fig. D–F) to WT levels. Collectively, these results demonstrate that merlin is a direct regulator of SC NPC growth and glial differentiation in vitro.


Nf2/Merlin controls spinal cord neural progenitor function in a Rac1/ErbB2-dependent manner.

Garcia C, Gutmann DH - PLoS ONE (2014)

Wild-type, but not mutant, merlin re-expression restores SC NPC properties to WT levels.(A) Re-expression of WT (MSCV.NF2), but not mutant (MSCV.NF2.L64P), merlin reduced (B) SC NPC growth (diameter) and clonogenic expansion (neurospheres) to WT levels (diameters: MSCV, p<0.001; L64P, p<0.001; hNf2, p = 0.1584; average number of neurospheres: MSCV, p<0.0421; L64P, p<0.05; hNf2, p = 0.7138; two-way ANOVA with Bonferroni post-test). (C) Wild-type (WT; MSCV.NF2), but not mutant (MSCV.NF2.L64P), merlin expression in Nf2−/− SC NPCs decreases cell number at day 8 (MSCV, p<0.001; L64P, p<0.05; hNf2, p = 0.200; two-way ANOVA with Bonferroni post-test) and (D) glial differentiation to WT levels (MSCV, p<0.001; L64P, p<0.001; hNf2, p = 0.7238; two-way ANOVA with Bonferroni post-test). Wild-type (WT; MSCV.NF2), but not mutant (MSCV.NF2.L64P), merlin expression in Nf2−/− NPCs increases (E) neuronal (MSCV, p<0.001; L64P, p<0.001; hNf2- p = 0.1797; two-way ANOVA with Bonferroni post-test) and (F) oligodendrocyte differentiation to WT levels (MSCV, p<0.01; L64P, p<0.01; hNf2, p = 0.7308; two-way ANOVA with Bonferroni post-test. The data were normalized to the field of view. Values denote the mean ± SEM. (*) p<0.05; (**) p<0.001; (***) p<0.0001.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4016309&req=5

pone-0097320-g002: Wild-type, but not mutant, merlin re-expression restores SC NPC properties to WT levels.(A) Re-expression of WT (MSCV.NF2), but not mutant (MSCV.NF2.L64P), merlin reduced (B) SC NPC growth (diameter) and clonogenic expansion (neurospheres) to WT levels (diameters: MSCV, p<0.001; L64P, p<0.001; hNf2, p = 0.1584; average number of neurospheres: MSCV, p<0.0421; L64P, p<0.05; hNf2, p = 0.7138; two-way ANOVA with Bonferroni post-test). (C) Wild-type (WT; MSCV.NF2), but not mutant (MSCV.NF2.L64P), merlin expression in Nf2−/− SC NPCs decreases cell number at day 8 (MSCV, p<0.001; L64P, p<0.05; hNf2, p = 0.200; two-way ANOVA with Bonferroni post-test) and (D) glial differentiation to WT levels (MSCV, p<0.001; L64P, p<0.001; hNf2, p = 0.7238; two-way ANOVA with Bonferroni post-test). Wild-type (WT; MSCV.NF2), but not mutant (MSCV.NF2.L64P), merlin expression in Nf2−/− NPCs increases (E) neuronal (MSCV, p<0.001; L64P, p<0.001; hNf2- p = 0.1797; two-way ANOVA with Bonferroni post-test) and (F) oligodendrocyte differentiation to WT levels (MSCV, p<0.01; L64P, p<0.01; hNf2, p = 0.7308; two-way ANOVA with Bonferroni post-test. The data were normalized to the field of view. Values denote the mean ± SEM. (*) p<0.05; (**) p<0.001; (***) p<0.0001.
Mentions: To establish a causal relationship between merlin loss and SC NPC function, merlin was re-expressed in Nf2-deficient NPCs by retroviral infection (Fig. 2A). In these experiments, expression of WT, but not NF2-patient mutant (L64P; [20], [21]), merlin restored SC NPC neurosphere diameters (Fig. 2B), clonogenic expansion (Fig. 2B), cell number (Fig. 2C), and multi-lineage differentiation (Fig. D–F) to WT levels. Collectively, these results demonstrate that merlin is a direct regulator of SC NPC growth and glial differentiation in vitro.

Bottom Line: We demonstrate that the Nf2 protein, merlin, negatively regulates spinal neural progenitor cell survival and glial differentiation in an ErbB2-dependent manner, and that NF2-associated spinal ependymomas exhibit increased ErbB2 activation.Moreover, we show that Nf2-deficient SC NPC ErbB2 activation results from Rac1-mediated ErbB2 retention at the plasma membrane.Collectively, these findings establish ErbB2 as a potential rational therapeutic target for NF2-associated spinal ependymoma.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, United States of America.

ABSTRACT

Objective: Individuals with the neurofibromatosis type 2 (NF2) cancer predisposition syndrome develop spinal cord glial tumors (ependymomas) that likely originate from neural progenitor cells. Whereas many spinal ependymomas exhibit indolent behavior, the only treatment option for clinically symptomatic tumors is surgery. In this regard, medical therapies are unfortunately lacking due to an incomplete understanding of the critical growth control pathways that govern the function of spinal cord (SC) neural progenitor cells (NPCs).

Methods: To identify potential therapeutic targets for these tumors, we leveraged primary mouse Nf2-deficient spinal cord neural progenitor cells.

Results: We demonstrate that the Nf2 protein, merlin, negatively regulates spinal neural progenitor cell survival and glial differentiation in an ErbB2-dependent manner, and that NF2-associated spinal ependymomas exhibit increased ErbB2 activation. Moreover, we show that Nf2-deficient SC NPC ErbB2 activation results from Rac1-mediated ErbB2 retention at the plasma membrane.

Significance: Collectively, these findings establish ErbB2 as a potential rational therapeutic target for NF2-associated spinal ependymoma.

Show MeSH
Related in: MedlinePlus