ENaCs as Both Effectors and Regulators of MiRNAs in Lung Epithelial Development and Regeneration

Epithelial sodium channels (ENaC) play an important role in re-absorbing excessive luminal fluid by building up an osmotic Na(+) gradient across the tight epithelium in the airway, the lung, the kidney, and the colon. The ENaC is a major pathway for retention of salt in kidney too. MicroRNAs (miRs), a group of non-coding RNAs that regulate gene expression at the post-transcriptional level, have emerged as a novel class of regulators for ENaC. Given the ENaC pathway is crucial for maintaining fluid homeostasis in the lung and the kidney and other cavities, we summarized the cross-talk between ENaC and miRs and recapitulated the underlying regulatory factors, including aldosterone, transforming growth factor-β1, and vascular endothelial growth factor-A in the lung and other epithelial tissues/organs. We have compared the profiling of miRs between normal and injured mice and human lungs, which showed a significant alteration in numerous miRs in mouse models of LPS and ventilator induced ARDS. In addition, we reiterated the potential regulation of the ENaC by miRs in stem/progenitor cell-based re-epithelialization, and identified a promising pharmaceutic target of ENaC for removing edema fluid in ARDS by mesenchymal stem cells-released paracrine. In conclusion, it seems that the interactions between miRs and scnn1s/ENaCs are critical for lung development, epithelial cell turnover in adult lungs, and re-epithelialization for repair.