SLC26 anion exchangers in uterine epithelial cells and spermatozoa: clues from the past and hints to the future



The solute carrier 26 (SLC26) family emerges as a distinct class of anion transporters with its members SLC26A3 (Slc26a3) and SLC26A6 (Slc26a6) reported to be electrogenic Cl/HCO3 exchangers. While it is known that uterine fluid has high HCO3 content and that HCO3 is essential for sperm capacitation, the molecular mechanisms underlying the transport of HCO3 across uterine epithelial cells and sperm have not been fully investigated. The present review re-examines the results from early reports studying anion transport, finding clues for the involvement of Cl/HCO3 anion exchangers in electrogenic HCO3 transport across endometrial epithelium. We also summarise recent work on Slc26a3 and Slc26a6 in uterine epithelial cells and sperm, revealing their functional role in working closely with the cystic fibrosis transmembrane conductance regulator (CFTR) for HCO3 transport in these cells. The possible involvement of these anion exchangers in other HCO3 dependent reproductive processes and their implications for infertility are also discussed.