Insulin regulates alveolar epithelial function by inducing Na+/K+-ATPase translocation to the plasma membrane in a process mediated by the action of Akt
Alejandro P. Comellas Journal of Cell Science,
Stimulation of Na+/K+-ATPase translocation to the cell surface increases active Na+ transport, which is the driving force of alveolar fluid reabsorption, a process necessary to keep the lungs free of edema and to allow normal gas exchange. Here, we provide evidence that insulin increases alveolar fluid reabsorption and Na+/K+-ATPase activity by increasing its translocation to the plasma membrane in alveolar epithelial cells. Insulin-induced Akt activation is necessary and sufficient to promote Na+/K+-ATPase translocation to the plasma membrane. Phosphorylation of AS160 by Akt is also required in this process, whereas inactivation of the Rab GTPase-activating protein domain of AS160 promotes partial Na+/K+-ATPase translocation in the absence of insulin. We found that Rab10 functions as a downstream target of AS160 in insulin-induced Na+/K+-ATPase translocation. Collectively, these results suggest that Akt plays a major role in Na+/K+-ATPase intracellular translocation and thus in alveolar fluid reabsorption.