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NOVA regulates Dcc alternative splicing during neuronal migration and axon guidance in the spinal cord.

Leggere JC, Saito Y, Darnell RB, Tessier-Lavigne M, Junge HJ, Chen Z - Elife (2016)

Bottom Line: RNA-binding proteins (RBPs) control multiple aspects of post-transcriptional gene regulation and function during various biological processes in the nervous system.We found that the NOVA family of RBPs play a key role in neuronal migration, axon outgrowth, and axon guidance.Together, our results demonstrate that the production of DCC splice variants controlled by NOVA has a crucial function during many stages of commissural neuron development.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, United States.

ABSTRACT
RNA-binding proteins (RBPs) control multiple aspects of post-transcriptional gene regulation and function during various biological processes in the nervous system. To further reveal the functional significance of RBPs during neural development, we carried out an in vivo RNAi screen in the dorsal spinal cord interneurons, including the commissural neurons. We found that the NOVA family of RBPs play a key role in neuronal migration, axon outgrowth, and axon guidance. Interestingly, Nova mutants display similar defects as the knockout of the Dcc transmembrane receptor. We show here that Nova deficiency disrupts the alternative splicing of Dcc, and that restoring Dcc splicing in Nova knockouts is able to rescue the defects. Together, our results demonstrate that the production of DCC splice variants controlled by NOVA has a crucial function during many stages of commissural neuron development.

No MeSH data available.


Related in: MedlinePlus

Nova dKO does not cause commissural axons to invade the motor column.(A) Immunohistochemistry of ROBO3 in Nova WT, Nova dKO, Dcc WT, and Dcc KO spinal cords. Only the ventral half is shown (MC, motor column). Some commissural axons in Dcc KO, but not in Nova dKO, are defasciculated and invade the motor column (arrows). (B) Quantification of phenotypes in A. The amount of commissural axons in the motor column is represented as the ratio between the ventral area covered by commissural axons and that of the total ventral area. Data are normalized to WT and are represented as the mean ± SEM (Student’s t-test, *p<0.05, ns, not significant). Scale bar, 50 μm.DOI:http://dx.doi.org/10.7554/eLife.14264.017
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fig6s1: Nova dKO does not cause commissural axons to invade the motor column.(A) Immunohistochemistry of ROBO3 in Nova WT, Nova dKO, Dcc WT, and Dcc KO spinal cords. Only the ventral half is shown (MC, motor column). Some commissural axons in Dcc KO, but not in Nova dKO, are defasciculated and invade the motor column (arrows). (B) Quantification of phenotypes in A. The amount of commissural axons in the motor column is represented as the ratio between the ventral area covered by commissural axons and that of the total ventral area. Data are normalized to WT and are represented as the mean ± SEM (Student’s t-test, *p<0.05, ns, not significant). Scale bar, 50 μm.DOI:http://dx.doi.org/10.7554/eLife.14264.017

Mentions: Loss of Netrin-DCC mediated attraction in vivo reduces the number of commissural axons that are able to reach the midline (Fazeli et al., 1997; Serafini et al., 1996; Xu et al., 2014). We thus examined commissural axon guidance to the midline using immunostaining of the axonal markers ROBO3 and TAG-1. We found that at E10.5 and E11.5, the intensity of these axonal markers from the ventral half of the spinal cord was significantly reduced in Nova dKOs, suggesting a reduction of ventral axon projection (Figure 6). At E11.5, there are usually two main commissural axon bundles. Both are reduced in Nova dKOs and the more lateral one is more profoundly affected. The size of the ventral commissure, formed by axons crossing the midline, is also reduced (Figure 6). By E12.5, the reduction in the commissure size is still significant but is somewhat alleviated than at earlier stages. A similar reduction in axons reaching and crossing the ventral midline is also seen in Dcc KOs (Fazeli et al., 1997; Xu et al., 2014). The severity of the defect is similar between Nova and Dcc mutants (Figure 6). One distinction between the two mutants is that Dcc KO axons are defasciculated and often invade the motor column (Xu et al., 2014), whereas such a defect was not observed in Nova dKOs (Figure 6—figure supplement 1).10.7554/eLife.14264.016Figure 6.Nova dKO disrupts commissural axon ventral projection.


NOVA regulates Dcc alternative splicing during neuronal migration and axon guidance in the spinal cord.

Leggere JC, Saito Y, Darnell RB, Tessier-Lavigne M, Junge HJ, Chen Z - Elife (2016)

Nova dKO does not cause commissural axons to invade the motor column.(A) Immunohistochemistry of ROBO3 in Nova WT, Nova dKO, Dcc WT, and Dcc KO spinal cords. Only the ventral half is shown (MC, motor column). Some commissural axons in Dcc KO, but not in Nova dKO, are defasciculated and invade the motor column (arrows). (B) Quantification of phenotypes in A. The amount of commissural axons in the motor column is represented as the ratio between the ventral area covered by commissural axons and that of the total ventral area. Data are normalized to WT and are represented as the mean ± SEM (Student’s t-test, *p<0.05, ns, not significant). Scale bar, 50 μm.DOI:http://dx.doi.org/10.7554/eLife.14264.017
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4930329&req=5

fig6s1: Nova dKO does not cause commissural axons to invade the motor column.(A) Immunohistochemistry of ROBO3 in Nova WT, Nova dKO, Dcc WT, and Dcc KO spinal cords. Only the ventral half is shown (MC, motor column). Some commissural axons in Dcc KO, but not in Nova dKO, are defasciculated and invade the motor column (arrows). (B) Quantification of phenotypes in A. The amount of commissural axons in the motor column is represented as the ratio between the ventral area covered by commissural axons and that of the total ventral area. Data are normalized to WT and are represented as the mean ± SEM (Student’s t-test, *p<0.05, ns, not significant). Scale bar, 50 μm.DOI:http://dx.doi.org/10.7554/eLife.14264.017
Mentions: Loss of Netrin-DCC mediated attraction in vivo reduces the number of commissural axons that are able to reach the midline (Fazeli et al., 1997; Serafini et al., 1996; Xu et al., 2014). We thus examined commissural axon guidance to the midline using immunostaining of the axonal markers ROBO3 and TAG-1. We found that at E10.5 and E11.5, the intensity of these axonal markers from the ventral half of the spinal cord was significantly reduced in Nova dKOs, suggesting a reduction of ventral axon projection (Figure 6). At E11.5, there are usually two main commissural axon bundles. Both are reduced in Nova dKOs and the more lateral one is more profoundly affected. The size of the ventral commissure, formed by axons crossing the midline, is also reduced (Figure 6). By E12.5, the reduction in the commissure size is still significant but is somewhat alleviated than at earlier stages. A similar reduction in axons reaching and crossing the ventral midline is also seen in Dcc KOs (Fazeli et al., 1997; Xu et al., 2014). The severity of the defect is similar between Nova and Dcc mutants (Figure 6). One distinction between the two mutants is that Dcc KO axons are defasciculated and often invade the motor column (Xu et al., 2014), whereas such a defect was not observed in Nova dKOs (Figure 6—figure supplement 1).10.7554/eLife.14264.016Figure 6.Nova dKO disrupts commissural axon ventral projection.

Bottom Line: RNA-binding proteins (RBPs) control multiple aspects of post-transcriptional gene regulation and function during various biological processes in the nervous system.We found that the NOVA family of RBPs play a key role in neuronal migration, axon outgrowth, and axon guidance.Together, our results demonstrate that the production of DCC splice variants controlled by NOVA has a crucial function during many stages of commissural neuron development.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, United States.

ABSTRACT
RNA-binding proteins (RBPs) control multiple aspects of post-transcriptional gene regulation and function during various biological processes in the nervous system. To further reveal the functional significance of RBPs during neural development, we carried out an in vivo RNAi screen in the dorsal spinal cord interneurons, including the commissural neurons. We found that the NOVA family of RBPs play a key role in neuronal migration, axon outgrowth, and axon guidance. Interestingly, Nova mutants display similar defects as the knockout of the Dcc transmembrane receptor. We show here that Nova deficiency disrupts the alternative splicing of Dcc, and that restoring Dcc splicing in Nova knockouts is able to rescue the defects. Together, our results demonstrate that the production of DCC splice variants controlled by NOVA has a crucial function during many stages of commissural neuron development.

No MeSH data available.


Related in: MedlinePlus