KEY POINTS: Proteolytic activation of the epithelial sodium channel (ENaC) was compromised by transmembrane serine protease 2 deficiency in murine cortical collecting duct cells and native mouse kidney. To compensate for impaired ENaC activation, rise in plasma aldosterone in response to low-salt diet was enhanced in BACKGROUND: The renal epithelial sodium channel (ENaC) is essential for sodium balance and BP control. ENaC undergoes complex proteolytic activation by not yet clearly identified tubular proteases. Here, we examined a potential role of transmembrane serine protease 2 (TMPRSS2). METHODS: Murine ENaC and TMPRSS2 were (co)expressed in RESULTS: In oocytes, coexpression of murine TMPRSS2 and ENaC resulted in fully cleaved CONCLUSIONS: TMPRSS2 contributes to proteolytic ENaC activation in mouse kidney