Aquaporin 2

Aquaporin 2 (AQP2) is a protein that in humans is encoded by the AQP2 gene. It is a water channel protein expressed in the kidney and plays a crucial role in maintaining water balance within the body.

Function

Aquaporin 2 is found in the cell membrane of the principal cells of the collecting duct in the kidney. It is responsible for reabsorbing water from the urine, a process regulated by the hormone vasopressin (also known as antidiuretic hormone or ADH). When vasopressin binds to its receptor (V2R) on the cell surface, it triggers a cascade of intracellular events that result in the insertion of AQP2 into the cell membrane, thereby increasing water permeability and promoting water reabsorption.

Clinical significance

Mutations in the AQP2 gene can lead to rare genetic disorders such as nephrogenic diabetes insipidus (NDI), a condition characterized by excessive thirst and excretion of large amounts of dilute urine. This is due to the kidney's inability to respond to vasopressin and reabsorb water, despite the presence of normal or elevated levels of the hormone.

Research

Research into Aquaporin 2 has potential implications for the treatment of conditions such as congestive heart failure, liver cirrhosis, and syndrome of inappropriate antidiuretic hormone (SIADH), where water balance is disrupted.

See also

• Aquaporin
• Vasopressin receptor 2
• Nephrogenic diabetes insipidus