%T Neuronal activity disrupts myelinated axon integrity in the absence of NKCC1b %V 219 %A KLH Marshall-Phelps %A L Kegel %A M Baraban %A T Ruhwedel %A RG Almeida %A M Rubio-Brotons %A A Klingseisen %A SK Benito-Kwiecinski %A JJ Early %A JM Bin %A D Suminaite %A MR Livesey %A W Möbius %A RJ Poole %A DA Lyons %N 7 %D 2020 %K Cell signaling %J Journal of Cell Biology %L discovery10098423 %C United States %X Through a genetic screen in zebrafish, we identified a mutant with disruption to myelin in both the CNS and PNS caused by a mutation in a previously uncharacterized gene, slc12a2b, predicted to encode a Na+, K+, and Cl− (NKCC) cotransporter, NKCC1b. slc12a2b/NKCC1b mutants exhibited a severe and progressive pathology in the PNS, characterized by dysmyelination and swelling of the periaxonal space at the axon–myelin interface. Cell-type–specific loss of slc12a2b/NKCC1b in either neurons or myelinating Schwann cells recapitulated these pathologies. Given that NKCC1 is critical for ion homeostasis, we asked whether the disruption to myelinated axons in slc12a2b/NKCC1b mutants is affected by neuronal activity. Strikingly, we found that blocking neuronal activity completely prevented and could even rescue the pathology in slc12a2b/NKCC1b mutants. Together, our data indicate that NKCC1b is required to maintain neuronal activity–related solute homeostasis at the axon–myelin interface, and the integrity of myelinated axons. %O This article is available under a Creative Commons License (Attribution 4.0 International, as described at https://creativecommons.org/licenses/by/4.0/).