Identification and properties of a novel variant of NBC4 (Na+/HCO3− co-transporter 4) that is predominantly expressed in the choroid plexus
Secretion of HCO3− at the apical side of the epithelial cells of the choroid plexus is an essential step in the formation of cerebrospinal fluid. Anion conductance with a high degree of HCO3− permeability has been observed and suggested to be the major pathway for HCO3− transport across the apical membrane. Recently, it was found that NBC (Na+/HCO3− co-transporter) 4, an electrogenic member of the NBC family, was expressed in the choroid plexus. We found that a novel variant of the NBC4 [NBC4g/Slc4a5 (solute carrier family 4, sodium bicarbonate co-transporter, member 5)] is almost exclusively expressed in the apical membrane of rat choroid plexus epithelium at exceptionally high levels. RNA interference-mediated knockdown allowed the functional demonstration that NBC4g is the major player in the HCO3− transport across the apical membrane of the choroid plexus epithelium. When combined with a recent observation that in choroid plexus epithelial cells electrogenic NBC operates with a stoichiometry of 3:1, the results of the present study suggest that NBC4g mediates the efflux of HCO3− and contributes to cerebrospinal fluid production.
Epigenetic silencing of gene expression is important in cancer. Aberrant DNA CpG island hypermethylation and histone modifications are involved in the aberrant silencing of tumour-suppressor genes. LSD1 (lysine-specific demethylase 1) is a H3K4 (histone H3 Lys4) demethylase associated with ... more
Distinct spatiotemporal Ca2+ signalling events regulate fundamental aspects of eukaryotic cell physiology. Complex Ca2+ signals can be driven by release of Ca2+ from intracellular organelles that sequester Ca2+ such as the ER (endoplasmic reticulum) or through the opening of Ca2+-permeable ... more
Genetically modified mice mimicking ODDD (oculodentodigital dysplasia), a disease characterized by reduced Cx43 (connexin 43)-mediated gap junctional intercellular communication, represent an in vivo model to assess the role of Cx43 in mammary gland development and function. We previously ... more