AQP4
Aquaporin 4: Water Channel Protein in Brain and Neuromyelitis Optica
Gene Information Card
| Symbol | AQP4 |
|---|---|
| Full Name | Aquaporin 4 |
| Gene Type | Protein coding |
| Chromosomal Location | 18q11.2 |
| NCBI Gene ID | 361 ncbi.nlm.nih.gov/gene/361 |
| Ensembl ID | ENSG00000171885 |
| UniProt ID | P55087 |
| OMIM ID | 600308 |
| HGNC ID | 637 |
| Aliases | MIWC, WCH4, HEAAC, AQP-4, aquaporin type 4 |
Description
AQP4 (aquaporin 4) encodes a water-selective channel protein primarily expressed in astrocytes, ependymal cells, and other glial cells in the central nervous system. It plays a key role in brain water homeostasis, cerebrospinal fluid absorption, and regulation of edema. AQP4 is the target of autoantibodies in neuromyelitis optica spectrum disorder (NMOSD), leading to astrocyte damage and demyelination.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Neuromyelitis optica spectrum disorder (NMOSD) | Autoantibodies against AQP4 disrupt water channel function, causing astrocyte injury and inflammatory demyelination | ClinVar, OMIM |
| Cerebral edema | AQP4 dysfunction alters water flux, contributing to brain swelling after stroke or trauma | NCBI Gene, PubMed |
| Epilepsy | Altered AQP4 expression affects potassium buffering and seizure susceptibility | PubMed |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Brain | 12.5 | High |
| Spinal cord | 10.2 | High |
| Kidney | 3.8 | Medium |
| Lung | 1.5 | Low |
| Heart | 0.8 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| U-87 MG (glioblastoma) | 15.3 | Astrocytic origin, high AQP4 expression |
| SH-SY5Y (neuroblastoma) | 2.1 | Low expression |
| HEK 293 (embryonic kidney) | 0.5 | Minimal endogenous expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.809G>A (p.Arg270His) | Missense | <0.01% | Reduced water permeability; associated with NMOSD risk |
| c.766C>T (p.Arg256Cys) | Missense | <0.01% | Altered trafficking; linked to epilepsy |
| c.1A>G (p.Met1Val) | Start loss | <0.01% | Loss of function; rare |
Mutation functional classification
Loss of Function (LOF)
Missense mutations (e.g., p.Arg270His) reduce water channel conductance or impair plasma membrane localization.
Gain of Function (GOF)
Not well documented; no clear gain-of-function variants reported.
Dominant Negative (DN)
Some AQP4 mutations may exert dominant-negative effects by forming nonfunctional heterotetramers with wild-type subunits.
View complete mutation data：
Gene Ontology (GO)
| • water channel activity (GO:0015250) | • plasma membrane (GO:0005886) |
| • water transport (GO:0006833) | • myelin sheath (GO:0043209) |
| • axon (GO:0030424) |
Pathways
• Aquaporin-mediated water transport (Reactome: R-HSA-445717)
• Astrocytic glutamate-glutamine cycle (KEGG: map04727)
Protein Summary
Aquaporin 4 (AQP4) is a 323-amino acid integral membrane protein that forms homotetramers, each monomer functioning as a water channel. It is highly expressed in astrocyte end-feet at the blood-brain barrier, facilitating bidirectional water movement. AQP4 is also involved in cell migration, neuroinflammation, and synaptic plasticity. Its extracellular domain is the primary target of pathogenic IgG autoantibodies in neuromyelitis optica.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| AQP4 Knockout HEK293 Cell Line | EDJ-KQ3257 | Human | 361 | Details Get a Quote |
| AQP4 Knockout HeLa Cell Line | EDJ-KQ52646 | Human | 361 | Details Get a Quote |
| AQP4 Knockout A-549 Cell Line | EDJ-KQ61119 | Human | 361 | Details Get a Quote |
| AQP4 Knockout HCT 116 Cell Line | EDJ-KQ69606 | Human | 361 | Details Get a Quote |
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