NKCC1 (SLC12a2) induces a secondary axis in Xenopus laevis embryos independently of its co-transporter function

NKCC1 is a broadly expressed Na + –K + –Cl − co-transporter involved in regulation of ion flux across the cell membrane and in regulating cell volume. Whilst much is known about the co-transporter activity of NKCC1 and its regulation by protein kinases and phosphatases, little is known about the activities of NKCC1 that are co-transporter independent. In this report we show that over-expression of NKCC1 in embryos of Xenopus laevis induces secondary axes , independently of its co-transporter activity. In addition, over-expression of NKCC1 results in the formation of neural tissue in ectodermal explants. We also show that NKCC1 is expressed broadly but non-uniformly in embryos of Xenopus laevis and Xenopus tropicalis , with prominent expression in the notochord, nervous system and stomach. These results provide insights into an additional, previously unreported activity of NKCCl.