Proteolytic activation of the human epithelial sodium channel by trypsin IV and trypsin I involves distinct cleavage sites

Härteis S, Krappitz A, Krappitz M, Murphy JE, Bertog M, Krüger B, Nacken R, Chung H, Hollenberg MD, Knecht W, Bunnett NW, Korbmacher C (2014)

Publication Type: Journal article

Publication year: 2014

Journal

Publisher: American Society for Biochemistry and Molecular Biology

Book Volume: 289

Pages Range: 19067-78

Journal Issue: 27

DOI: 10.1074/jbc.M113.538470

Abstract

Proteolytic activation is a unique feature of the epithelial sodium channel (ENaC). However, the underlying molecular mechanisms and the physiologically relevant proteases remain to be identified. The serine protease trypsin I can activate ENaC in vitro but is unlikely to be the physiologically relevant activating protease in ENaC-expressing tissues in vivo. Herein, we investigated whether human trypsin IV, a form of trypsin that is co-expressed in several extrapancreatic epithelial cells with ENaC, can activate human ENaC. In Xenopus laevis oocytes, we monitored proteolytic activation of ENaC currents and the appearance of ?ENaC cleavage products at the cell surface. We demonstrated that trypsin IV and trypsin I can stimulate ENaC heterologously expressed in oocytes. ENaC cleavage and activation by trypsin IV but not by trypsin I required a critical cleavage site (Lys-189) in the extracellular domain of the ?-subunit. In contrast, channel activation by trypsin I was prevented by mutating three putative cleavage sites (Lys-168, Lys-170, and Arg-172) in addition to mutating previously described prostasin (RKRK(178)), plasmin (Lys-189), and neutrophil elastase (Val-182 and Val-193) sites. Moreover, we found that trypsin IV is expressed in human renal epithelial cells and can increase ENaC-mediated sodium transport in cultured human airway epithelial cells. Thus, trypsin IV may regulate ENaC function in epithelial tissues. Our results show, for the first time, that trypsin IV can stimulate ENaC and that trypsin IV and trypsin I activate ENaC by cleavage at distinct sites. The presence of distinct cleavage sites may be important for ENaC regulation by tissue-specific proteases.

Authors with CRIS profile

Involved external institutions

University of California San Francisco (UCSF) United States (USA) (US) University of Calgary Canada (CA) AstraZeneca UK Limited United Kingdom (GB) Monash University Australia (AU)

How to cite

APA:

Härteis, S., Krappitz, A., Krappitz, M., Murphy, J.E., Bertog, M., Krüger, B.,... Korbmacher, C. (2014). Proteolytic activation of the human epithelial sodium channel by trypsin IV and trypsin I involves distinct cleavage sites. Journal of Biological Chemistry, 289(27), 19067-78. https://doi.org/10.1074/jbc.M113.538470

MLA:

Härteis, Silke, et al. "Proteolytic activation of the human epithelial sodium channel by trypsin IV and trypsin I involves distinct cleavage sites." Journal of Biological Chemistry 289.27 (2014): 19067-78.

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