The influence of aquaporin-4 isoform interaction on supramolecular water channel assembly in astrocytoma cells

Abstract

Traumatic brain injury (TBI) is often complicated by the development of brain edema. Despite its clinical importance, the underlying pathological mechanisms are poorly understood. Nevertheless, a central role for aquaporin-4 (AQP4) has been suggested. AQP4 is the predominant water channel of the central nervous system, where it forms supramolecular structures named orthogonal arrays of particles (OAP). This organization is essential for channel opening. OAP formation is regulated by the differential expression of its two major isoforms, AQP4-M1 and AQP4-M23. Loss of OAP affects brain edema, as it results in impaired water accumulation and clearance. In the present study, the dynamic behavior of AQP4-M1 and AQP4-M23 in the cell membrane of astrocytoma cells was investigated by microfluorimetric techniques. Furthermore, the effect of histamine exposure, which is extensively released following TBI, on OAP in AQP4 expressing cells was explored.