Figure 2.

Control of sodium transport by mineralocorticoids in CD principal cells. The steroid hormone aldosterone binds to intracellular mineralocorticoid receptor (MR) that translocates into the nucleus where it activates a transcriptional program inducing expression of modulators of sodium transport such as SGK1. SGK1 phosphorylates and inhibits Nedd-4.2, thereby increasing apical ENaC density via decreased ubiquitination, internalization and degradation of ENaC. SGK1 also increases expression of Na⁺,K⁺-ATPase and ENaC subunits. Sustained aldosterone stimulation increases the transcription of αENaC and Na,K-ATPase.