SCAPER Gene
<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#f0f0f0;">SCAPER</th></tr>
<tr><td><b>Full Name</b></td><td>S-Phase Cyclin-Associated Protein Homolog</td></tr>
<tr><td><b>Symbol</b></td><td>SCAPER</td></tr>
<tr><td><b>Chromosome</b></td><td>15q24.2</td></tr>
<tr><td><b>NCBI Gene ID</b></td><td>55856</td></tr>
<tr><td><b>OMIM ID</b></td><td>611493</td></tr>
<tr><td><b>Ensembl ID</b></td><td>ENSG00000141741</td></tr>
<tr><td><b>UniProt ID</b></td><td>[Q9BYX4](https://www.uniprot.org/uniprot/Q9BYX4)</td></tr>
<tr><td><b>Protein Length</b></td><td>1,328 amino acids</td></tr>
<tr><td><b>Associated Diseases</b></td><td>[Parkinson's Disease](/diseases/parkinsons-disease), Retinitis Pigmentosa</td></tr>
</table>
</div>
Overview
SCAPER (S-Phase Cyclin-Associated Protein Homolog) is a protein coding gene located on chromosome 15q24.2. The gene encodes a 1,328 amino acid protein containing multiple WD40 repeat domains that mediate protein-protein interactions. SCAPER is primarily involved in cell cycle regulation during S-phase, where it serves as a regulatory partner for cyclin-dependent kinases (CDKs), and participates in DNA damage response pathways. Genome-wide association studies (GWAS) have identified SCAPER as a susceptibility locus for [Parkinson's Disease](/diseases/parkinsons-disease), suggesting a role in dopaminergic neuron survival. Loss-of-function mutations in SCAPER cause autosomal recessive retinitis pigmentosa, indicating its essential function in maintaining cellular homeostasis in highly specialized neurons [@nalls2019][@zanette2019].
Molecular Function
Protein Structure
SCAPER belongs to the uncharacterized protein family UPF05456 and contains multiple WD40 repeat domains at its C-terminus. These domains form a beta-propeller structure that serves as a scaffold for protein-protein interactions. The protein localizes to both the nucleus and cytoplasm, consistent with its roles in cell cycle regulation and DNA damage response [@ohi2005].
Cell Cycle Regulation
SCAPER functions as a regulatory partner during S-phase of the cell cycle:
- CDK Partner: SCAPER interacts with cyclin-dependent kinases (particularly CDK2) and modulates their activity during DNA synthesis
- S-Phase Checkpoint: SCAPER helps coordinate DNA replication with cell cycle progression, preventing replication stress
- G1/S Transition: Emerging evidence suggests SCAPER participates in the G1 to S-phase transition checkpoint
DNA Damage Response
SCAPER participates in cellular responses to DNA damage:
- Checkpoint Activation: Following genotoxic stress, SCAPER may help activate cell cycle checkpoints to allow DNA repair
- DNA Repair Coordination: The WD40 repeat domains may scaffold DNA repair complexes at sites of damage
- Neuronal Relevance: Post-mitotic neurons rely on efficient DNA repair mechanisms; SCAPER dysfunction could contribute to genomic instability in dopaminergic neurons [@chan2018]
Disease Associations
Parkinson's Disease
SCAPER variants have been associated with [Parkinson's Disease](/diseases/parkinsons-disease) risk in large-scale GWAS meta-analyses. The gene is expressed in [dopaminergic neurons](/entities/neurons) of the [substantia nigra pars compacta](/brain-regions/substantia-nigra), the neuronal population most vulnerable in PD. The association between SCAPER and PD risk suggests several potential mechanisms [@nalls2019]:
| Mechanism | Description | Evidence |
|-----------|-------------|----------|
| Cell cycle re-entry | Aberrant re-activation of cell cycle machinery in post-mitotic neurons leads to apoptosis | [@chan2018] |
| DNA damage accumulation | Impaired DNA repair pathways lead to genomic instability and neuronal death | [@chang2019] |
| Transcriptional dysregulation | Altered gene expression programs critical for neuronal survival | GWAS signal colocalization |
| Mitochondrial dysfunction | SCAPER variants may affect mitochondrial quality control pathways | Indirect evidence |
Retinitis Pigmentosa
Homozygous or compound heterozygous loss-of-function mutations in SCAPER cause autosomal recessive retinitis pigmentosa (RP), characterized by progressive photoreceptor cell death leading to night blindness, tunnel vision, and eventual complete blindness. This indicates SCAPER's essential role in maintaining cellular homeostasis in retinal cells [@zanette2019].
Expression Pattern
SCAPER is expressed in various tissues with notable expression in:
- Brain regions: [Cerebral cortex](/brain-regions/cortex), [hippocampus](/brain-regions/hippocampus), [substantia nigra](/brain-regions/substantia-nigra), cerebellum, and basal ganglia
- Retina: High expression in photoreceptor cells
- Other tissues: Testis, skeletal muscle, and proliferating cells
Single-cell RNA-seq data from the substantia nigra shows SCAPER expression in dopaminergic neurons, supporting its relevance to [Parkinson's Disease](/diseases/parkinsons-disease) pathogenesis.
Therapeutic Implications
Drug Targets
Currently, SCAPER is not a primary drug target, but understanding its role in neuronal survival provides insights for therapeutic development:
- CDK modulators: CDK inhibitors (e.g., ribociclib, palbociclib) may indirectly affect SCAPER pathway activity
- DNA repair enhancers: Agents that enhance DNA damage repair (e.g., poly(ADP-ribose) polymerase inhibitors) could compensate for SCAPER dysfunction
- Cell cycle inhibitors: Preventing aberrant cell cycle re-entry in neurons
Research Directions
Key areas for future investigation include:
Functional validation of GWAS-identified SCAPER variants in dopaminergic neurons
Mechanistic studies linking SCAPER to specific PD pathways (mitochondrial dysfunction, protein aggregation)
CRISPR screening to identify synthetic lethal interactions with SCAPER loss
Gene therapy approaches for SCAPER-related retinal disordersSee Also
- [Parkinson's Disease](/diseases/parkinsons-disease) — Movement disorder associated with SCAPER
- [Cell Cycle Re-entry in Neurodegeneration](/mechanisms/cell-cycle-re-entry) — Aberrant cell cycle activation
- [DNA Damage Response](/mechanisms/dna-damage-response) — Cellular stress pathways
- [Substantia Nigra](/brain-regions/substantia-nigra) — Brain region with SCAPER expression
- [Dopaminergic Neurons](/entities/neurons) — Cell type vulnerable in PD