Aquaporins in the Spinal Cord

Abstract

Aquaporins (AQPs) are water channel proteins robustly expressed in the central nervous system (CNS). A number of previous studies described the cellular expression sites and investigated their major roles and function in the brain and spinal cord. Among thirteen different mammalian AQPs, AQP1 and AQP4 have been mainly studied in the CNS and evidence has been presented that they play important roles in the pathogenesis of CNS injury, edema and multiple diseases such as multiple sclerosis, neuromyelitis optica spectrum disorders, amyotrophic lateral sclerosis, glioblastoma multiforme, Alzheimer’s disease and Parkinson’s disease. The objective of this review is to highlight the current knowledge about AQPs in the spinal cord and their proposed roles in pathophysiology and pathogenesis related to spinal cord lesions and injury.

Exosomes co‐expressing AQP5‐targeting miRNAs and IL‐4 receptor‐binding peptide inhibit the migration of human breast cancer cells

“…Several subtypes of AQPs also transport glycerol across the biomembranes . Dysregulation of AQPs is associated with a number of pathophysiological conditions, for example, nephrogenic diabetes insipidus, body water retention, brain edema, neuromyelitis optica, and Sjögren's syndrome . Recently, several studies importantly demonstrated that AQPs play a critical role in the migration of cancer cells and metastasis of tumors .…”

“…4 Dysregulation of AQPs is associated with a number of pathophysiological conditions, for example, nephrogenic diabetes insipidus, body water retention, brain edema, neuromyelitis optica, and Sjögren's syndrome. [5][6][7][8] Recently, several studies importantly demonstrated that AQPs play a critical role in the migration of cancer cells and metastasis of tumors. [9][10][11][12] In particular, we have shown that increased expression of AQP5 in the breast cancer cells was associated with cancer cell migration, metastasis, and poor prognosis in human patients.…”

Aquaporin‐4 expression dynamically varies after acute spinal cord injury‐induced disruption of blood spinal cord barrier in rats

“…After acute SCI, BSCB integrity is impaired mechanically and protoplasmic astrocytes lose their polarity and turn swollen. Other astrocytes with increased AQP4 expression migrate to the site of injury quickly, withdrawing spinal cord edema and rebuilding the BSCB . Some studies also showed that swollen astrocytes in the early stage of SCI were significantly reduced in AQP4‐knockout models.…”

“…Other astrocytes with increased AQP4 expression migrate to the site of injury quickly, withdrawing spinal cord edema and rebuilding the BSCB. 15 Some studies also showed that swollen astrocytes in the early stage of SCI were significantly reduced in AQP4-knockout models. However, in some vasogenic edema-dominated animal models, the knockout of AQP4 raised the water content and aggravated tissue swelling, which impeded the recovery of nerve function 16 In conclusion, AQP4 is involved both in cytotoxic edema and the resolution of BSCB damagerelated vascular edema, and AQP4 might facilitate cytotoxic edema at earlier stages while aiding the clearance of vasogenic edema at later stages.…”

Metformin as Potential Therapy for High-Grade Glioma

“…Another mechanism that may affect the development of brain edema is the level of expression of aquaporin-4 protein (AQP4). It is a protein belonging to the aquaporin family, which is the most common aquaporin channel in CNS [262][263][264]. Its increased expression concerns the structure of the blood-brain barrier [265].…”