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NOVA2-mediated RNA regulation is required for axonal pathfinding during development.

Saito Y, Miranda-Rottmann S, Ruggiu M, Park CY, Fak JJ, Zhong R, Duncan JS, Fabella BA, Junge HJ, Chen Z, Araya R, Fritzsch B, Hudspeth AJ, Darnell RB - Elife (2016)

Bottom Line: The neuron specific RNA-binding proteins NOVA1 and NOVA2 are highly homologous alternative splicing regulators.NOVA proteins regulate at least 700 alternative splicing events in vivo, yet relatively little is known about the biologic consequences of NOVA action and in particular about functional differences between NOVA1 and NOVA2.Thus we have discovered that NOVA2 uniquely regulates alternative splicing of a coordinate set of transcripts encoding key components in cortical, brainstem and spinal axon guidance/outgrowth pathways during neural differentiation, with severe functional consequences in vivo.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, New York, United States.

ABSTRACT
The neuron specific RNA-binding proteins NOVA1 and NOVA2 are highly homologous alternative splicing regulators. NOVA proteins regulate at least 700 alternative splicing events in vivo, yet relatively little is known about the biologic consequences of NOVA action and in particular about functional differences between NOVA1 and NOVA2. Transcriptome-wide searches for isoform-specific functions, using NOVA1 and NOVA2 specific HITS-CLIP and RNA-seq data from mouse cortex lacking either NOVA isoform, reveals that NOVA2 uniquely regulates alternative splicing events of a series of axon guidance related genes during cortical development. Corresponding axonal pathfinding defects were specific to NOVA2 deficiency: Nova2-/- but not Nova1-/- mice had agenesis of the corpus callosum, and axonal outgrowth defects specific to ventral motoneuron axons and efferent innervation of the cochlea. Thus we have discovered that NOVA2 uniquely regulates alternative splicing of a coordinate set of transcripts encoding key components in cortical, brainstem and spinal axon guidance/outgrowth pathways during neural differentiation, with severe functional consequences in vivo.

No MeSH data available.


Related in: MedlinePlus

Loss of corpus callosum in Nova2-/- but not Nova1-/- mice.(A) Immunohistochemistry of L1 (a,d,g,j), TAG1 (b,e,h,k) proteins, and DAPI (c,f,I,l) on horizontal sections in E18.5 wild-type (a–c, g–i) and Nova2-/- (d–f, j–l) littermates. (g–l) Higher magnified view of anterior commissure region of (a-–f). Arrows indicated Probst bundles. Scale bars; 500 μm. (B) Serial section images of L1 immunostaining from anterior brain position to posterior. Wild-type images shows on left panels and Nova2-/- images on right panels. Scale bar; 500 μm. (C) Coronal brain sections of E18.5 wild-type (a–d) and Nova2-/- (e–h) littermates, stained for L1 (green; aand e), Neuropilin-1 (a pioneer axon marker; red; b and f), DAPI (blue;cand g), and merged views (d and h). Scale bar; 500 um. (D) Normal formation of corpus callosum in Nova1-/- mice. Coronal brain sections of E18.5 wild-type and Nova1-/- littermates, stained for L1 (upper panels), NOVA1 (middle panels), and DAPI (lower panels). Scale bar; 500 um. (E) Commissure axons pathfinding defect in Nova2-/- mice. Coronal sections in wild-type (a) and Nova2-/- (b) mice showing anterogradely labeled fibers after DiI crystal placements in lateral neocortex. Asterisks: DiI placed positions. Scale bars; 500 μm.DOI:http://dx.doi.org/10.7554/eLife.14371.021
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fig6s1: Loss of corpus callosum in Nova2-/- but not Nova1-/- mice.(A) Immunohistochemistry of L1 (a,d,g,j), TAG1 (b,e,h,k) proteins, and DAPI (c,f,I,l) on horizontal sections in E18.5 wild-type (a–c, g–i) and Nova2-/- (d–f, j–l) littermates. (g–l) Higher magnified view of anterior commissure region of (a-–f). Arrows indicated Probst bundles. Scale bars; 500 μm. (B) Serial section images of L1 immunostaining from anterior brain position to posterior. Wild-type images shows on left panels and Nova2-/- images on right panels. Scale bar; 500 μm. (C) Coronal brain sections of E18.5 wild-type (a–d) and Nova2-/- (e–h) littermates, stained for L1 (green; aand e), Neuropilin-1 (a pioneer axon marker; red; b and f), DAPI (blue;cand g), and merged views (d and h). Scale bar; 500 um. (D) Normal formation of corpus callosum in Nova1-/- mice. Coronal brain sections of E18.5 wild-type and Nova1-/- littermates, stained for L1 (upper panels), NOVA1 (middle panels), and DAPI (lower panels). Scale bar; 500 um. (E) Commissure axons pathfinding defect in Nova2-/- mice. Coronal sections in wild-type (a) and Nova2-/- (b) mice showing anterogradely labeled fibers after DiI crystal placements in lateral neocortex. Asterisks: DiI placed positions. Scale bars; 500 μm.DOI:http://dx.doi.org/10.7554/eLife.14371.021

Mentions: The observations that NOVA2 regulates alternative splicing events in transcripts encoding axon guidance signaling factors led us to test whether axon guidance itself is affected in Nova2 mice. When coronal and horizontal sections of E18.5 mice brains were double-immunostained for L1, an axonal marker, and TAG-1, a corticofugal axon marker, we discovered that Nova2-/- mice, but not wild-type littermates, had agenesis of the corpus callosum (ACC) (14/14 mice) (Figure 6 and Figure 6—figure supplement 1A). ACC was in all Nova2-/- mice serial sections examined (Figure 6—figure supplement 1B), was seen along with Probst bundles (abnormal collections of cells characteristically seen in patients with ACC; arrows in Figure 6A–o and Figure 6—figure supplement 1A–l), and was also clearly evident in sections stained with the pioneer axon marker Neuropilin-1 (Figure 6—figure supplement 1C). Interestingly, Nova1-/- mice showed normal CC formation (Figure 6—figure supplement 1D). The anterior commissure axons were observed in both Nova2-/- and Nova1-/- mice (Figure 6—figure supplement 2).10.7554/eLife.14371.020Figure 6.Agenesis of corpus callosum in Nova2-/- mice.


NOVA2-mediated RNA regulation is required for axonal pathfinding during development.

Saito Y, Miranda-Rottmann S, Ruggiu M, Park CY, Fak JJ, Zhong R, Duncan JS, Fabella BA, Junge HJ, Chen Z, Araya R, Fritzsch B, Hudspeth AJ, Darnell RB - Elife (2016)

Loss of corpus callosum in Nova2-/- but not Nova1-/- mice.(A) Immunohistochemistry of L1 (a,d,g,j), TAG1 (b,e,h,k) proteins, and DAPI (c,f,I,l) on horizontal sections in E18.5 wild-type (a–c, g–i) and Nova2-/- (d–f, j–l) littermates. (g–l) Higher magnified view of anterior commissure region of (a-–f). Arrows indicated Probst bundles. Scale bars; 500 μm. (B) Serial section images of L1 immunostaining from anterior brain position to posterior. Wild-type images shows on left panels and Nova2-/- images on right panels. Scale bar; 500 μm. (C) Coronal brain sections of E18.5 wild-type (a–d) and Nova2-/- (e–h) littermates, stained for L1 (green; aand e), Neuropilin-1 (a pioneer axon marker; red; b and f), DAPI (blue;cand g), and merged views (d and h). Scale bar; 500 um. (D) Normal formation of corpus callosum in Nova1-/- mice. Coronal brain sections of E18.5 wild-type and Nova1-/- littermates, stained for L1 (upper panels), NOVA1 (middle panels), and DAPI (lower panels). Scale bar; 500 um. (E) Commissure axons pathfinding defect in Nova2-/- mice. Coronal sections in wild-type (a) and Nova2-/- (b) mice showing anterogradely labeled fibers after DiI crystal placements in lateral neocortex. Asterisks: DiI placed positions. Scale bars; 500 μm.DOI:http://dx.doi.org/10.7554/eLife.14371.021
© Copyright Policy
Related In: Results  -  Collection

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fig6s1: Loss of corpus callosum in Nova2-/- but not Nova1-/- mice.(A) Immunohistochemistry of L1 (a,d,g,j), TAG1 (b,e,h,k) proteins, and DAPI (c,f,I,l) on horizontal sections in E18.5 wild-type (a–c, g–i) and Nova2-/- (d–f, j–l) littermates. (g–l) Higher magnified view of anterior commissure region of (a-–f). Arrows indicated Probst bundles. Scale bars; 500 μm. (B) Serial section images of L1 immunostaining from anterior brain position to posterior. Wild-type images shows on left panels and Nova2-/- images on right panels. Scale bar; 500 μm. (C) Coronal brain sections of E18.5 wild-type (a–d) and Nova2-/- (e–h) littermates, stained for L1 (green; aand e), Neuropilin-1 (a pioneer axon marker; red; b and f), DAPI (blue;cand g), and merged views (d and h). Scale bar; 500 um. (D) Normal formation of corpus callosum in Nova1-/- mice. Coronal brain sections of E18.5 wild-type and Nova1-/- littermates, stained for L1 (upper panels), NOVA1 (middle panels), and DAPI (lower panels). Scale bar; 500 um. (E) Commissure axons pathfinding defect in Nova2-/- mice. Coronal sections in wild-type (a) and Nova2-/- (b) mice showing anterogradely labeled fibers after DiI crystal placements in lateral neocortex. Asterisks: DiI placed positions. Scale bars; 500 μm.DOI:http://dx.doi.org/10.7554/eLife.14371.021
Mentions: The observations that NOVA2 regulates alternative splicing events in transcripts encoding axon guidance signaling factors led us to test whether axon guidance itself is affected in Nova2 mice. When coronal and horizontal sections of E18.5 mice brains were double-immunostained for L1, an axonal marker, and TAG-1, a corticofugal axon marker, we discovered that Nova2-/- mice, but not wild-type littermates, had agenesis of the corpus callosum (ACC) (14/14 mice) (Figure 6 and Figure 6—figure supplement 1A). ACC was in all Nova2-/- mice serial sections examined (Figure 6—figure supplement 1B), was seen along with Probst bundles (abnormal collections of cells characteristically seen in patients with ACC; arrows in Figure 6A–o and Figure 6—figure supplement 1A–l), and was also clearly evident in sections stained with the pioneer axon marker Neuropilin-1 (Figure 6—figure supplement 1C). Interestingly, Nova1-/- mice showed normal CC formation (Figure 6—figure supplement 1D). The anterior commissure axons were observed in both Nova2-/- and Nova1-/- mice (Figure 6—figure supplement 2).10.7554/eLife.14371.020Figure 6.Agenesis of corpus callosum in Nova2-/- mice.

Bottom Line: The neuron specific RNA-binding proteins NOVA1 and NOVA2 are highly homologous alternative splicing regulators.NOVA proteins regulate at least 700 alternative splicing events in vivo, yet relatively little is known about the biologic consequences of NOVA action and in particular about functional differences between NOVA1 and NOVA2.Thus we have discovered that NOVA2 uniquely regulates alternative splicing of a coordinate set of transcripts encoding key components in cortical, brainstem and spinal axon guidance/outgrowth pathways during neural differentiation, with severe functional consequences in vivo.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, New York, United States.

ABSTRACT
The neuron specific RNA-binding proteins NOVA1 and NOVA2 are highly homologous alternative splicing regulators. NOVA proteins regulate at least 700 alternative splicing events in vivo, yet relatively little is known about the biologic consequences of NOVA action and in particular about functional differences between NOVA1 and NOVA2. Transcriptome-wide searches for isoform-specific functions, using NOVA1 and NOVA2 specific HITS-CLIP and RNA-seq data from mouse cortex lacking either NOVA isoform, reveals that NOVA2 uniquely regulates alternative splicing events of a series of axon guidance related genes during cortical development. Corresponding axonal pathfinding defects were specific to NOVA2 deficiency: Nova2-/- but not Nova1-/- mice had agenesis of the corpus callosum, and axonal outgrowth defects specific to ventral motoneuron axons and efferent innervation of the cochlea. Thus we have discovered that NOVA2 uniquely regulates alternative splicing of a coordinate set of transcripts encoding key components in cortical, brainstem and spinal axon guidance/outgrowth pathways during neural differentiation, with severe functional consequences in vivo.

No MeSH data available.


Related in: MedlinePlus