DDX20: DEAD-Box Helicase 20
A multifunctional RNA helicase involved in spliceosome assembly, gene regulation, and innate immunity
Gene Information Card
| Symbol | DDX20 |
|---|---|
| Full Name | DEAD-Box Helicase 20 |
| Gene Type | Protein-coding |
| Chromosomal Location | 1p13.2 |
| NCBI Gene ID | 11218 ncbi.nlm.nih.gov/gene/11218 |
| Ensembl ID | ENSG00000164741 |
| UniProt ID | Q9UHI6 |
| OMIM ID | 606168 |
| HGNC ID | 2742 |
| Aliases | Gemin3, DP103, DEAD-box protein 20 |
Description
DDX20, also known as Gemin3 or DP103, encodes a member of the DEAD-box family of RNA helicases. The protein is a core component of the survival of motor neurons (SMN) complex, essential for spliceosomal snRNP assembly. It also functions in transcriptional regulation, microRNA processing, and innate immune signaling. DDX20 is ubiquitously expressed and has been implicated in spinal muscular atrophy, viral infections, and various cancers.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Spinal Muscular Atrophy (SMA) | DDX20 interacts with SMN1; mutations in the SMN complex disrupt snRNP assembly, leading to motor neuron degeneration. | OMIM #253300; PMID: 10549278 |
| Prostate Cancer | DDX20 overexpression correlates with androgen receptor signaling and tumor progression. | COSMIC; PMID: 21746835 |
| Hepatocellular Carcinoma | DDX20 upregulation promotes cell proliferation via NF-κB pathway. | COSMIC; PMID: 25636800 |
| Viral Infections (e.g., HIV-1, HCV) | DDX20 acts as a cofactor for viral replication by modulating RNA metabolism and innate immunity. | UniProt; PMID: 19029303 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 12.5 | High |
| Brain | 8.2 | Medium |
| Liver | 6.1 | Medium |
| Heart | 4.3 | Low |
| Lung | 3.9 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 10.1 | Cervical cancer cell line |
| HEK293 | 9.5 | Embryonic kidney cell line |
| HepG2 | 7.8 | Hepatocellular carcinoma cell line |
| K562 | 6.2 | Leukemia cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1123G>A (p.Gly375Arg) | Missense | <0.1% | Altered helicase activity; reported in SMA patients |
| c.1567C>T (p.Arg523Trp) | Missense | <0.1% | Reduced SMN complex binding |
| c.2014A>G (p.Ile672Val) | Missense | 0.2% | Unknown significance |
| c.2450_2451insA (p.Asn817Lysfs*3) | Frameshift | <0.1% | Loss of function; truncation |
Mutation functional classification
Loss of Function (LOF)
Frameshift and nonsense mutations (e.g., p.Asn817Lysfs*3) lead to truncated protein, disrupting SMN complex assembly and RNA helicase activity.
Gain of Function (GOF)
Not well characterized; some missense variants (e.g., p.Gly375Arg) may alter substrate specificity in cancer contexts.
Dominant Negative (DN)
Missense mutations (e.g., p.Arg523Trp) that impair SMN binding without complete loss of protein may exert dominant-negative effects on snRNP assembly.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Spliceosome (Reactome: R-HSA-72163)
• SMN complex assembly (Reactome: R-HSA-191859)
• Innate immune system (Reactome: R-HSA-168249)
Protein Summary
DDX20 (Gemin3) is a 824-amino-acid DEAD-box RNA helicase that localizes to the cytoplasm and nucleus. It contains a conserved helicase domain with ATP-binding and RNA-unwinding activities. As part of the SMN complex, it facilitates the assembly of spliceosomal U snRNPs. DDX20 also interacts with transcription factors (e.g., E2F1, p53) and viral proteins, modulating gene expression and antiviral responses. Post-translational modifications include phosphorylation and sumoylation, which regulate its stability and interactions.
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