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| Symbol | NOVA2 |
| Full Name |
NOVA Alternative Splicing Regulator 2 (Neuro-Oncological Ventral Antigen 2) |
| Chromosome |
19p13.3 |
| NCBI Gene |
4858 |
| Ensembl |
ENSG00000104967 |
| OMIM |
601991 |
| UniProt |
Q9UNW9 |
| Diseases |
[Alzheimer's Disease](/diseases/alzheimers-disease), [Huntington's Disease](/diseases/huntingtons-disease), [Epilepsy](/diseases/epilepsy) |
| Expression |
[Neurons](/entities/neurons) (neocortex, hippocampus), Vascular endothelium |
NOVA2 (NOVA Alternative Splicing Regulator 2), also known as Neuro-Oncological Ventral Antigen 2, encodes a neuron-specific KH-type RNA-binding protein on chromosome 19p13.3 that functions as a master regulator of alternative splicing in the forebrain and cortex. NOVA2 is the paralog of NOVA1, and together these two proteins constitute the NOVA family, which governs the most extensively characterized neuron-specific splicing regulatory network in mammals.
While NOVA1 predominates in the hindbrain and spinal cord, NOVA2 is the dominant NOVA family member in the cerebral cortex and hippocampus, making it especially relevant to higher cognitive functions and cortical neurodegenerative diseases such as Alzheimer's disease. NOVA2 regulates the splicing, polyadenylation, and localization of hundreds of neuronal pre-mRNAs, with targets highly enriched for synaptic and axon guidance molecules.
¶ Gene Structure and Protein Products
The NOVA2 gene is located on chromosome 19p13.3, spanning approximately 79 kb with 8 exons. Despite divergent genomic locations, NOVA1 and NOVA2 share ~75% amino acid identity, particularly within their KH RNA-binding domains.
The NOVA2 protein (492 amino acids) contains three KH (K-Homology) RNA-binding domains:
- KH1, KH2, KH3 domains: Each adopts a βααββα fold; KH3 is the primary RNA-recognition domain, directly contacting YCAY tetranucleotide motifs with high specificity
- Linker regions: Flexible regions between KH domains that contribute to multivalent RNA binding
- Nuclear/cytoplasmic shuttling signals: Enable activity-dependent redistribution between nucleus and dendrites
Despite structural similarity, NOVA2 has distinct properties:
- Regional specificity: NOVA2 predominates in cortex/hippocampus; NOVA1 in hindbrain/spinal cord
- Target preferences: While sharing many targets, NOVA2 uniquely regulates cortical axon guidance molecules and excitatory synapse components
- Developmental timing: NOVA2 expression peaks later in development, coinciding with cortical maturation
NOVA2 is the primary splicing regulator in cortical and hippocampal neurons:
- Target scope: CLIP-seq studies identify ~1,400 NOVA2 binding sites in mouse brain, regulating ~500 alternative splicing events
- Positional splicing code: Like NOVA1, binding downstream of an exon promotes inclusion; upstream binding promotes skipping
- Cooperative binding: Multiple NOVA2 molecules bind clustered YCAY elements, creating switch-like regulation of target exons
NOVA2 regulates transcripts essential for cortical circuit formation and function:
| Target |
Regulated Event |
Functional Impact |
| DCC (Netrin receptor) |
Exon 17 |
Axon midline crossing in cortex |
| Dab1 (Reelin pathway) |
Exon 7b/7c |
Cortical layer positioning |
| GRIN1 (NR1) |
Exon 5 |
NMDA receptor properties at cortical synapses |
| NRXN1 (Neurexin-1) |
SS4 |
Excitatory vs inhibitory synapse specification |
| NLGN1 (Neuroligin-1) |
Splice site B |
Excitatory synapse development |
| Robo2 |
Alternative exons |
Cortical axon guidance |
| SLIT2 |
Multiple exons |
Cortical neuron migration |
NOVA2 is essential for proper cortical wiring:
- Axon guidance: Nova2 knockout mice show severe cortical axon pathfinding defects, including failure of commissural crossing and aberrant corticospinal tract projections
- Cortical lamination: NOVA2 regulates Dab1 splicing, which is critical for Reelin-dependent neuronal migration and layer formation
- Synaptogenesis: Alternative splicing of neurexin and neuroligin genes by NOVA2 specifies excitatory/inhibitory synapse identity
- Dendritic development: NOVA2 targets include cytoskeletal regulators that control dendritic arborization
Uniquely among neuronal splicing factors, NOVA2 is also expressed in vascular endothelium:
- Regulates alternative splicing of adhesion molecules in endothelial cells
- Controls angiogenesis during brain vascular development
- Endothelial NOVA2 loss disrupts blood-brain barrier formation
Beyond splicing, NOVA2 regulates 3' end processing:
- Controls alternative polyadenylation site selection for hundreds of neuronal transcripts
- Affects mRNA stability, localization, and translation through 3' UTR length changes
- 3' UTR regulation by NOVA2 is particularly important for dendritic mRNA targeting
NOVA2 dysfunction is increasingly linked to Alzheimer's disease:
- Expression decline: NOVA2 protein levels decrease in the cortex and hippocampus of AD patients, correlating with Braak stage and cognitive decline
- Splicing alterations: Hundreds of NOVA2-dependent exons show altered inclusion in AD cortex, affecting synaptic proteins, glutamate receptors, and cell adhesion molecules
- Tau connection: NOVA2 may contribute to MAPT exon 10 splicing regulation in the cortex; loss of NOVA2 could contribute to tau isoform imbalance
- Synaptic loss correlation: NOVA2-regulated splicing changes correlate with synaptic density loss, a major driver of cognitive decline in AD
- Amyloid toxicity: Aβ oligomers can downregulate NOVA2 expression through translational repression, creating a feed-forward cycle of splicing dysfunction
In Huntington's disease:
- NOVA2-dependent splicing events are disrupted in the caudate and cortex of HD patients
- Mutant huntingtin protein sequesters NOVA2 in nuclear inclusions
- Striatal medium spiny neurons show particularly severe NOVA2 target mis-splicing
- NOVA2 variants have been identified in patients with focal epilepsy
- NOVA2 conditional knockout mice develop spontaneous seizures
- Loss of NOVA2-dependent GABA and glutamate receptor splicing disrupts excitatory/inhibitory balance in cortical circuits
- NOVA2 regulates splicing of SCN1A and SCN8A sodium channel transcripts, which are major epilepsy genes
- NOVA2 target exons overlap significantly with autism-associated splicing changes
- Cortical circuit miswiring due to NOVA2 dysfunction may contribute to ASD features
- NOVA2 regulates splicing of multiple high-confidence ASD risk genes (NRXN1, SHANK3, NLGN1)
NOVA2 shows a complementary pattern to NOVA1:
- Cerebral cortex: Highest expression; all cortical layers, particularly layers II/III and V
- Hippocampus: Strong expression in CA1–CA3 pyramidal neurons and dentate gyrus granule cells
- Striatum: Moderate expression in medium spiny neurons
- Amygdala: Moderate expression
- Olfactory bulb: Moderate expression
- Thalamus: Low-moderate expression
- Cerebellum: Minimal (NOVA1 predominates)
- Brainstem/spinal cord: Minimal (NOVA1 predominates)
- Primarily expressed in excitatory pyramidal neurons
- Lower expression in inhibitory interneurons (where NOVA1 may have greater relative contribution)
- Endothelial expression (unique among neuronal splicing factors)
- Not expressed in glia
- Expression begins at ~E13.5 in mouse cortex, coinciding with the onset of cortical neurogenesis
- Increases throughout postnatal development, peaking in young adulthood
- Gradual decline with aging, potentially contributing to age-related splicing changes
- Antisense oligonucleotides (ASOs): Correction of specific NOVA2-regulated mis-splicing events in AD could restore synaptic function without needing to rescue NOVA2 itself
- Splice-switching oligonucleotides (SSOs): Targeting individual NOVA2-dependent exons in disease-relevant transcripts
- NOVA2 expression restoration: Gene therapy or small molecules to maintain NOVA2 levels during aging and disease
- NOVA2-dependent splicing signatures in CSF exosomal RNA as biomarkers for cortical neurodegeneration
- Blood-based splicing biomarkers leveraging NOVA2's endothelial expression
- Ule et al., An RNA map predicting Nova-dependent splicing regulation (2006)
- Saito et al., NOVA2-mediated RNA regulation is required for axonal pathfinding during development (2016)
- Licatalosi et al., HITS-CLIP yields genome-wide insights into brain alternative RNA processing (2008)
- NOVA1 — NOVA alternative splicing regulator 1 (paralog)
- TARDBP — TDP-43, RNA-binding protein in ALS/FTD
- FUS — RNA-binding protein in ALS
- RBFOX1 — Neuronal splicing regulator
- RNA Splicing Defects — Splicing dysfunction in neurodegeneration
- Spliceosome — Pre-mRNA splicing machinery
- MAPT — Microtubule-associated protein tau (splicing target)