Molecular pathways for water fluxes in mouse choroid plexus epithelial cells (1182.3)

Abstract

Regulation and maintenance of cerebrospinal fluid (CSF) composition is crucial for brain function. Choroid plexus epithelial cells (CPECs) secrete most of the CSF and regulate its ion and water composition. However, the mechanisms of secretion and absorption of water across choroid plexus epithelium (CPE) are poorly understood. Secretion of CSF entails net water movement across CPECs from the basolateral membrane (blood‐facing) through the apical membrane (CSF‐facing). Water fluxes across cell membranes occur through aquaporin channels and cotransporters like the Na+‐K+‐2Cl‐ cotransporter 1 (NKCC1). Both NKCC1 and aquaporin‐1 (AQP1) are expressed in the CPECs apical membrane but are undetectable in the basolateral membrane. The inward water flux across the basolateral membrane of CPECs may be explained by the expression of other members of the gene families of AQPs and/or the cation‐coupled chloride cotransporters (slc12a). Using RT‐PCR, we detected transcripts for several AQPs in whole choroid plexus tissue. Transcripts for AQPs 1, 4, 7, but not 9, have so far been found. Immunolabeling studies in process will reveal the location of these proteins in the various components of the choroid plexus. Explaining the mechanisms of CSF production and absorption is key for understanding pathologies like hydrocephalous and increased intracranial pressure that cause brain ischemia and/or edema. Grant Funding Source: Supported by 226119 Seed Grant Proteomics Program 2012 Boonshoft School of Medicine