CIAO1: Cytosolic Iron-Sulfur Assembly Component 1
A key adaptor protein in cytosolic iron-sulfur cluster biogenesis and genome stability
Gene Information Card
| Symbol | CIAO1 |
|---|---|
| Full Name | Cytosolic Iron-Sulfur Assembly Component 1 |
| Gene Type | Protein-coding |
| Chromosomal Location | 2q33.1 |
| NCBI Gene ID | 93974 ncbi.nlm.nih.gov/gene/93974 |
| Ensembl ID | ENSG00000144381 |
| UniProt ID | Q9H6K1 |
| OMIM ID | 616631 |
| HGNC ID | 24280 |
| Aliases | CIA1, WD40 repeat protein 39 (WDR39) |
Description
CIAO1 (Cytosolic Iron-Sulfur Assembly Component 1) encodes a WD40-repeat protein that functions as an essential adaptor in the cytosolic iron-sulfur (Fe-S) cluster assembly (CIA) pathway. It interacts with the CIA targeting complex to facilitate the insertion of Fe-S clusters into cytosolic and nuclear target proteins, including DNA polymerases and helicases, thereby supporting DNA replication, repair, and genome stability.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| CIAO1-related disorder (autosomal recessive) | Loss-of-function mutations impair Fe-S cluster delivery, leading to mitochondrial dysfunction and multi-system abnormalities | OMIM #616631 |
| Cancer (pan-cancer) | Altered CIAO1 expression may affect DNA repair enzyme activity, contributing to genomic instability | COSMIC; TCGA data |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 12.5 | High |
| Bone marrow | 8.2 | Medium |
| Brain | 6.1 | Medium |
| Liver | 5.8 | Medium |
| Heart | 4.3 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 10.1 | High expression |
| HeLa | 9.4 | High expression |
| K562 | 7.8 | Medium expression |
| HepG2 | 6.5 | Medium expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | Missense/Start loss | Rare | Loss of protein expression; likely pathogenic |
| c.325C>T (p.Arg109Trp) | Missense | <0.01% | Impaired interaction with CIA targeting complex |
| c.682G>A (p.Glu228Lys) | Missense | <0.01% | Reduced Fe-S cluster transfer activity |
Mutation functional classification
Loss of Function (LOF)
Missense mutations (e.g., p.Arg109Trp) disrupt protein-protein interactions, reducing Fe-S cluster delivery.
Gain of Function (GOF)
Not reported.
Dominant Negative (DN)
Not reported.
View complete mutation data：
Gene Ontology (GO)
| • cytosol (GO:0005829) | • nucleus (GO:0005634) |
| • iron-sulfur cluster assembly (GO:0016226) | • protein targeting to mitochondrion (GO:0030091) |
| • protein binding (GO:0005515) |
Pathways
• Cytosolic iron-sulfur cluster assembly (CIA) pathway
• DNA replication and repair (via Fe-S cluster delivery to DNA polymerases)
Protein Summary
CIAO1 is a 343-amino acid WD40-repeat protein that localizes to the cytosol and nucleus. It acts as a scaffold within the CIA targeting complex, bridging the Fe-S cluster transfer machinery to apoproteins. Its structure comprises seven WD40 repeats forming a beta-propeller domain that mediates interactions with partner proteins such as MMS19 and FAM96B.
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