Differential expression of electrogenic NBC1 (SLC4A4) variants in rat kidney and pancreas

• Published in: Biochemical and biophysical research communications 2004-02, Vol.314 (2), p.382-389
• Main Authors: Roussa, Eleni, Nastainczyk, Wolfgang, Thévenod, Frank
• Format: Article
• Language: English
• Subjects: Acid–base homeostasis; Animals; Biological Transport; Blotting, Western; Cell Membrane - metabolism; Electrophoresis, Polyacrylamide Gel; Epithelia; Epitopes; HCO 3− transporters; Hydrogen-Ion Concentration; Immunoblotting; Immunohistochemistry; Immunolocalization; Kidney - metabolism; Kidney Cortex - metabolism; Microscopy, Fluorescence; Pancreas - metabolism; Protein Structure, Tertiary; Rats; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; Sodium-Bicarbonate Symporters - biosynthesis; Sodium-Bicarbonate Symporters - chemistry; Subcellular Fractions
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2003.12.099

The purpose of this study was to determine expression and localization of NH 2-terminal variants of the electrogenic Na +–HCO 3 − co-transporter NBC1 (SLC4A4) in the rat kidney and pancreas. We generated two anti-peptide antibodies: α333 against the “mste” start (kidney; kNBC1) and α332 against the “mede” start (pancreas; pNBC1). Transcripts for both NBC1 variants were detected in kidney and pancreas by RT-PCR, though kNBC1 was more prominent in the kidney and pNBC1 was more prominent in the pancreas. Similar protein expression levels were detected by immunoblotting of plasma membranes (PM) from kidney cortex and pancreas. Immunohistochemistry with α333 recognized the “mste”-epitope in the basolateral plasma membrane (BLM) of renal proximal tubule. The “mede”-protein (α332) was similarly localized although staining was much less and more diffuse. In the pancreas, α332 stained BLM of acinar and duct cells. Some isolated duct cells were also stained at the apical PM. The “mste”-protein (α333) was absent in acinar cells but was located at the apical PM of duct cells. The data indicate that the two NH 2-terminal NBC1 variants are co-expressed in kidney and pancreas, where they may contribute to HCO 3 − transport and pH regulation.