DDX55: DEAD-Box Helicase 55
A putative RNA helicase involved in ribosome biogenesis and cellular proliferation
Gene Information Card
| Symbol | DDX55 |
|---|---|
| Full Name | DEAD-Box Helicase 55 |
| Gene Type | Protein coding |
| Chromosomal Location | 12q24.31 |
| NCBI Gene ID | 57696 ncbi.nlm.nih.gov/gene/57696 |
| Ensembl ID | ENSG00000111364 |
| UniProt ID | Q8NHQ9 |
| OMIM ID | 617841 |
| HGNC ID | 20087 |
| Aliases | FLJ12529, MGC13170 |
Description
DDX55 encodes a member of the DEAD-box family of RNA helicases, characterized by the conserved motif Asp-Glu-Ala-Asp (DEAD). These proteins are involved in RNA secondary structure remodeling, ribosome biogenesis, pre-mRNA splicing, and translation initiation. DDX55 is implicated in cell proliferation and has been associated with various cancers.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Hepatocellular carcinoma | Overexpression promotes cell proliferation and migration; knockdown reduces tumor growth | PMID: 31495882 |
| Colorectal cancer | Upregulation correlates with poor prognosis; involved in Wnt/β-catenin signaling | PMID: 32561758 |
| Breast cancer | High expression associated with aggressive subtypes and reduced survival | PMID: 31073040 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 12.5 | Medium |
| Bone marrow | 9.8 | Medium |
| Lymph node | 8.2 | Low |
| Brain | 6.1 | Low |
| Liver | 5.4 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 14.3 | Cervical adenocarcinoma |
| K562 | 11.7 | Chronic myeloid leukemia |
| A549 | 10.2 | Lung carcinoma |
| HepG2 | 9.5 | Hepatocellular carcinoma |
| MCF7 | 8.8 | Breast adenocarcinoma |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1012C>T (p.Arg338Trp) | Missense | <0.01% | Unknown; reported in COSMIC |
| c.1456G>A (p.Glu486Lys) | Missense | <0.01% | Unknown; reported in COSMIC |
| c.1789_1790insA (p.Thr597Asnfs*2) | Frameshift | <0.01% | Predicted loss of function |
Mutation functional classification
Loss of Function (LOF)
Frameshift mutations (e.g., p.Thr597Asnfs*2) are predicted to truncate the protein, likely impairing helicase activity and RNA processing.
Gain of Function (GOF)
No confirmed gain-of-function mutations reported in DDX55.
Dominant Negative (DN)
No evidence for dominant-negative effects in DDX55.
View complete mutation data：
Gene Ontology (GO)
| • RNA helicase activity (GO:0003724) | • ATP binding (GO:0005524) |
| • RNA binding (GO:0003723) | • Ribosome biogenesis (GO:0042254) |
| • Cytoplasm (GO:0005737) | • Nucleus (GO:0005634) |
Pathways
• Ribosome biogenesis in eukaryotes (Reactome: R-HSA-6791226)
• Processing of Capped Intron-Containing Pre-mRNA (Reactome: R-HSA-72163)
Protein Summary
DDX55 is a 599-amino acid DEAD-box RNA helicase that localizes to the nucleus and cytoplasm. It contains conserved helicase domains (DEXDc and HELICc) and is involved in ATP-dependent RNA unwinding. The protein plays a role in ribosome assembly and has been linked to cancer cell proliferation.
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