Anoctamin 5 (ANO5, also known as TMEM16E) is a calcium-activated chloride channel encoded by the ANO5 gene located on chromosome 11p14.3. This protein belongs to the anoctamin family of membrane proteins that function as calcium-activated chloride channels (CaCCs) and phospholipid scramblases. While ANO5 is best characterized for its role in skeletal muscle disease, emerging research suggests potential implications in neuronal function and neurodegenerative processes.
| Property | Value |
|---|---|
| Symbol | ANO5 |
| Full Name | Anoctamin 5 |
| Aliases | TMEM16E, GDD1 |
| Chromosome | 11p14.3 |
| Gene ID | 203547 |
| Category | Ion Channel |
| Protein Class | Calcium-activated chloride channel |
ANO5 is a multipass membrane protein with eight predicted transmembrane domains. [1] The protein functions primarily as a calcium-activated chloride channel, though it also exhibits phospholipid scramblase activity. [2] Unlike other anoctamin family members, ANO5 has relatively low chloride channel activity and may function primarily as a scramblase involved in membrane lipid organization.
ANO5 is highly expressed in skeletal muscle and heart tissue, with lower expression in brain regions including the cortex, hippocampus, and cerebellum. [3] In the brain, ANO5 expression has been detected in neurons and glial cells, suggesting potential roles in neuronal signaling and homeostasis.
Mutations in ANO5 cause limb-girdle muscular dystrophy type 2L (LGMD2L) and distal myopathy, characterized by progressive weakness in proximal muscles. [4] These mutations typically result in loss of ANO5 protein function, leading to impaired calcium-dependent chloride transport in muscle fibers.
While direct associations between ANO5 and neurodegenerative diseases remain limited, several mechanisms suggest potential links:
Calcium Homeostasis: ANO5's role in calcium-activated chloride transport may influence neuronal calcium signaling, which is critical for synaptic function and vulnerable in Alzheimer's and Parkinson's diseases. [5]
Muscle-Brain Axis: Given the emerging understanding of muscle-brain crosstalk in neurodegeneration, ANO5-related muscle dysfunction may impact neuronal health through systemic mechanisms. [6]
Phospholipid Metabolism: ANO5's scramblase activity affects membrane lipid asymmetry, a process relevant to neuronal membrane trafficking and autophagy—both compromised in neurodegenerative conditions. [7]
Targeting ANO5 function remains challenging due to limited understanding of its neuronal roles. However, gene therapy approaches being developed for ANO5-related muscular dystrophy may have future applications in neuroprotection if neuronal functions are clarified. [8]
Further research is needed to:
Structure of anoctamin calcium-activated chloride channels - Nat Commun. ↩︎
ANO5 is a phospholipid scramblase with minimal chloride channel activity - J Cell Sci. ↩︎
Calcium dysregulation in Alzheimer's disease - Nat Rev Neurosci. ↩︎
Muscle-brain axis in neurodegeneration - Trends Neurosci. 2020. ↩︎