Fraser, S. A, Davies, M. R, Katerelos, M., Gleich, K., Choy, S., Steel, R., Galic, S., Mount, P. F, Kemp, B. E & Power, DA. (2014). Activation of AMPK reduces the co-transporter activity of NKCC1. Molecular Membrane Biology,31(2-3), 95-102. United Kingdom: Taylor & Francis. Retrieved from https://doi.org/10.3109/09687688.2014.902128
The co-transporter activity of Na+-K+-2Cl− 1 ( NKCC1 ) is dependent on phosphorylation. In this study we show the energy-sensing kinase AMPK inhibits NKCC1 activity. Three separate AMPK activators ( AICAR, Phenformin and A-769662 ) inhibited NKCC1 flux in a variety of nucleated cells. Treatment with A-769662 resulted in a reduction of NKCC1T212/T217 phosphorylation, and this was reversed by treatment with the non-selective AMPK inhibitor Compound C. AMPK dependence was confirmed by treatment of AMPK null mouse embryonic fibroblasts, where A-769662 had no effect on NKCC1 mediated transport. AMPK was found to directly phosphorylate a recombinant human-NKCC1 N-terminal fragment ( 1–293 ) with the phosphorylated site identified as S77. Mutation of Serine 77 to Alanine partially prevented the inhibitory effect of A-769662 on NKCC1 activity. In conclusion, AMPK can act to reduce NKCC1-mediated transport. While the exact mechanism is still unclear there is evidence for both a direct effect on phosphorylation of S77 and reduced phosphorylation of T212/217.
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