Editors' ChoiceSkin Biology

Rubbing sodium in a wound

Sci. Signal.  10 Nov 2015:
Vol. 8, Issue 402, pp. ec336
DOI: 10.1126/scisignal.aad8179

The skin serves as a critical barrier to the outside world that must be restored following injury. Water loss occurs during many skin disorders, resulting in an increase in extracellular Na+ concentration. Xu et al. report that the Na+ channel Nax functioned as a Na+ sensor that contributes to epithelial cell Na+ homeostasis. Nax was detected in multiple epithelial tissues and its abundance was increased in human skin with hypertrophic scars. Nax was necessary for increased Na+ influx and accumulation in epithelial cells exposed to increased extracellular Na+ concentration. Nax stimulated the expression of a gene encoding a protease that activates the Na+ channel ENaC, which mediated Na+ influx and accumulation in response to increased extracellular Na+ and was necessary for the production of mediators of epithelial cell proliferation and inflammation. Knocking down Nax in animal models decreased scarring and atopic dermatitis–like symptoms, indicating the importance of this sensor in epithelial cell homeostasis.

W. Xu, S. J. Hong, A. Zhong, P. Xie, S. Jia, Z. Xie, M. Zeitchek, S. Niknam-Bienia, J. Zhao, D. M. Porterfield, D. J. Surmeier, K. P. Leung, R. D. Galiano, T. A. Mustoe, Sodium channel Nax is a regulator in epithelial sodium homeostasis. Sci. Transl. Med. 7, 312ra177 (2015). [Abstract]