Abstract
Aquaporin-2 (AQP2) is a vasopressin-regulated water channel responsible for regulating water reabsorption through the apical plasma membrane of the principal cells of renal collecting ducts. It has been found that dysregulation and dysfunction of AQP2 cause many disorders related to water balance in people and animals, including polyuria and dilutional hyponatremia. Classically, AQP2 mRNA and protein expression and its membrane translocation are regulated by systemic vasopressin involving short-term regulation of AQP2 trafficking to and from the apical plasma membrane and long-term regulation of the total amount of the AQP2 protein in the cell. Recently, increasing evidence has demonstrated that collecting duct AQP2 expression and membrane translocation are also under the control of many other local factors, especially nuclear receptors. Here, we briefly review the progress of studies in this area and discuss the role of nuclear receptors in the regulation of water reabsorption via affecting AQP2 expression and function.
Highlights
Water is a basic necessity of life and is the main component of extracellular fluid
AQP1 is expressed in the proximal tubules and the descending thin limbs of the long loop nephrons responsible for constitutive absorption of a large amount of water, while AQP2–4 are located in the principal cells of the connecting tubules and collecting ducts in the kidney, where they control water reabsorption and determine the final urine volume [16]
This study demonstrates that PPARγ may take part in physiological regulation of water homeostasis independent of the arginine vasopressin (AVP)/cAMP/AQP2 pathway [44]
Summary
Water is a basic necessity of life and is the main component of extracellular fluid. Normally, the body’s water content (50%–60% of body weight) and osmotic pressure of extracellular fluid (280–295 mOsm/kg) play a critical role in maintaining homeostasis, which is achieved through the regulation of water intake and loss. AQP1 is expressed in the proximal tubules and the descending thin limbs of the long loop nephrons responsible for constitutive absorption of a large amount of water, while AQP2–4 are located in the principal cells of the connecting tubules and collecting ducts in the kidney, where they control water reabsorption and determine the final urine volume [16].
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