Molecular expression of SLC4-derived Na⁺-dependent anion transporters in selected human tissues

Abstract

NaHCO(3) transporters are involved in maintenance of intracellular pH and transepithelial HCO(3)(-) movement in many rodent tissues. To establish the human relevance of the many investigations on rodents, this study aimed to map these transporters and a related polypeptide, NaBC1 [solute carrier 4 (SLC4)A11], to several human tissues by using PCR on reverse transcribed human mRNA and immunoperoxidase histochemistry. The mRNA encoding the electroneutral Na(+):HCO(3)(-) cotransporter (NBCe1; SLC4A4), was expressed in renal cortex, renal medulla, stomach, duodenum, jejunum, ileum, colon, pancreas, choroid plexus, cerebellum, cerebrum, and hippocampus. NBCe2 (SLC4A5) and NBCn1 (SLC4A7) mRNAs were mainly found in kidney and brain tissues, as was mRNA encoding the Na(+)-dependent anion exchangers NCBE (SLC4A10) and NDCBE1 (SLC4A8). In addition to previous findings, NBCn1 protein was localized to human renal medullary thick ascending limbs and duodenal epithelial villus cells and NBCe2 protein to renal collecting ducts. Finally, the message encoding NaBC1 was found in kidney, stomach, duodenum, pancreas, and brain, and the corresponding protein in the anterior and posterior corneal epithelia, renal corpuscules, proximal tubules, collecting ducts, pancreatic ducts, and the choroid plexus epithelium. In conclusion, the selected human tissues display distinct expression patterns of HCO(3)(-) transporters, which closely resemble that of rodent tissues.

Synaptic Glutamate Release Is Modulated by the Na+-Driven Cl−/HCO3−Exchanger Slc4a8

“…This confirms previous data that antibodies generated to detect Slc4a8 labeled hippocampal pyramidal neurons (Damkier et al, 2007;Chen et al, 2008) but not astrocytes (Chen et al, 2008). Our costainings with presynaptic (vGLUT1, -2, -3; synaptophysin; NF68) and postsynaptic (PSD-95; MAP2) markers were in accordance with a mainly presynaptic localization of Slc4a8.…”

SLC4A11 Prevents Osmotic Imbalance Leading to Corneal Endothelial Dystrophy, Deafness, and Polyuria

“…Localization of lacZ activity matched the expression of the SLC4A11 protein in endothelial cells of the cornea as shown by immunofluorescence (Fig. 1B) using an antibody described previously (17). Specificity of the antibody is demonstrated using knock-out tissue (Fig.…”

“…Secondary antibodies and TOTO-3 were from Invitrogen. Anti-SLC4A11 antiserum (1:200) was a gift from J. Praetorius (17). Analysis was performed using an Axiophot microscope (Zeiss) or by confocal microscopy (Leica).…”

“…LacZ reporter and anti-SLC4A11 antibody staining (17) revealed that SLC4A11 is expressed in the endothelium of the cornea, in the thin descending part of Henle loop in the kidney, and in fibrocytes of the inner ear. SLC4A11 seems to play a major role at all these locations because its loss caused the following: (i) thickening of the stroma and Descement membrane concomitant with increased sodium chloride concentration in the stroma of the cornea; (ii) impaired urinary concentration, increased urinary volume, and increased urinary sodium loss in the kidney; and (iii) stress-induced morphological changes of fibrocytes of the inner ear resulting in deafness.…”

Modular structure of sodium-coupled bicarbonate transporters

“…This influx influences such hepatic functions as urea synthesis and gluconeogenesis (Kashiwagura et al, 1984). Apical NBCe2 immunoreactivity is reported in the membranes of bile duct cholangiocytes , renal collecting duct intercalated cells (Damkier et al, 2007), and uroepithelial cells in the renal pelvis . Apically expressed NBCe2 in choroid plexus epithelia (Praetorius and Nielson, 2004) operates with a 1:3 stoichiometry (Millar and Brown, 2008), secreting HCO 3 -into the cerebrospinal fluid.…”