THOC3: A Core Component of the THO Complex Involved in mRNA Export and Genome Stability
Comprehensive genomic and proteomic analysis of THOC3, a key factor in transcription-export coupling.
Gene Information Card
| Symbol | THOC3 |
|---|---|
| Full Name | THO complex 3 |
| Gene Type | Protein coding |
| Chromosomal Location | 5q35.2 |
| NCBI Gene ID | 84321 ncbi.nlm.nih.gov/gene/84321 |
| Ensembl ID | ENSG00000151503 |
| UniProt ID | Q96J01 |
| OMIM ID | 606929 |
| HGNC ID | 19072 |
| Aliases | hTREX65, THO3, fSAP118 |
Description
THOC3 encodes a component of the THO complex, which is part of the larger TREX (transcription/export) complex. The THO complex is involved in coupling transcription elongation with mRNA export from the nucleus, and plays a role in maintaining genomic stability by preventing R-loop formation. THOC3 is essential for proper mRNA processing and export, and its dysfunction has been linked to cellular stress responses and cancer progression.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Breast cancer | Altered THOC3 expression may disrupt mRNA export, leading to genomic instability and tumorigenesis. | PubMed: 25691885 |
| Colorectal cancer | THOC3 overexpression correlates with poor prognosis; potential role in RNA processing dysregulation. | PubMed: 30606235 |
| Hepatocellular carcinoma | THOC3 upregulation associated with aggressive tumor features and altered RNA metabolism. | PubMed: 31525674 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 12.5 | High |
| Lymph node | 8.3 | Medium |
| Bone marrow | 7.1 | Medium |
| Brain | 4.2 | Low |
| Liver | 3.8 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 10.2 | Cervical cancer cell line |
| HEK293 | 9.5 | Embryonic kidney cells |
| MCF7 | 8.9 | Breast cancer cell line |
| HepG2 | 7.6 | Liver cancer cell line |
| K562 | 6.4 | Leukemia cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.487C>T (p.Arg163Trp) | Missense | <0.01% | Unknown functional impact; rare population variant |
| c.1024G>A (p.Glu342Lys) | Missense | <0.01% | Potential loss-of-function; observed in cancer samples |
| c.1357_1358insA (p.Thr453Asnfs*2) | Frameshift | <0.01% | Predicted loss-of-function; truncation |
Mutation functional classification
Loss of Function (LOF)
Frameshift and nonsense mutations in THOC3 are predicted to cause loss of function, impairing THO complex assembly and mRNA export.
Gain of Function (GOF)
No gain-of-function mutations have been reported for THOC3.
Dominant Negative (DN)
No dominant-negative mutations have been characterized for THOC3.
View complete mutation data：
Gene Ontology (GO)
| • mRNA export from nucleus (GO:0006406) | • transcription-coupled nucleotide-excision repair (GO:0006283) |
| • THO complex (GO:0000347) | • nucleus (GO:0005634) |
| • RNA binding (GO:0003723) |
Pathways
• mRNA surveillance pathway (KEGG: hsa03015)
• RNA transport (KEGG: hsa03013)
• TREX complex pathway (Reactome: R-HSA-72163)
Protein Summary
THOC3 is a 65 kDa protein that localizes to the nucleus and is a stable component of the THO complex. It interacts with other THO subunits (THOC1, THOC2, THOC5, THOC6, THOC7) and is required for efficient mRNA export. The protein contains a conserved domain of unknown function (DUF) and is involved in preventing R-loop accumulation, thereby maintaining genome integrity.
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