| First Author | Carattino MD | Year | 2014 |
| Journal | Am J Physiol Renal Physiol | Volume | 307 |
| Issue | 9 | Pages | F1080-7 |
| PubMed ID | 25209858 | Mgi Jnum | J:216359 |
| Mgi Id | MGI:5608713 | Doi | 10.1152/ajprenal.00157.2014 |
| Citation | Carattino MD, et al. (2014) Prostasin interacts with the epithelial Na+ channel and facilitates cleavage of the gamma-subunit by a second protease. Am J Physiol Renal Physiol 307(9):F1080-7 |
| abstractText | During maturation, the alpha- and gamma-subunits of the epithelial Na+ channel (ENaC) undergo proteolytic processing by furin. Cleavage of the gamma-subunit by furin at the consensus site gammaRKRR143 and subsequent cleavage by a second protease at a distal site strongly activate the channel. For example, coexpression of prostasin with ENaC increases both channel function and cleavage at the gammaRKRK186 site. We generated a polyclonal antibody that recognizes the region 144-186 in the gamma-subunit (anti-gamma43) to determine whether prostasin promotes the release of the intervening tract between the putative furin and gammaRKRK186 cleavage sites. Anti-gamma43 precipitated both full-length (93 kDa) and furin-processed (83 kDa) gamma-subunits from extracts obtained from oocytes expressing alphabetaHA-gamma-V5 channels, but only the full-length (93 kDa) gamma-subunit from oocytes expressing alphabetaHA-gamma-V5 channels and either wild-type or a catalytically inactive prostasin. Although both wild-type and catalytically inactive prostasin activated ENaCs in an aprotinin-sensitive manner, only wild-type prostasin bound to aprotinin beads, suggesting that catalytically inactive prostasin facilitates the cleavage of the gamma-subunit by an endogenous protease in Xenopus oocytes. As dietary salt restriction increases cleavage of the renal gamma-subunit, we assessed release of the 43-mer inhibitory tract on rats fed a low-Na+ diet. We found that a low-Na+ diet increased gamma-subunit cleavage detected with the anti-gamma antibody and dramatically reduced the fraction precipitated with the anti-gamma43 antibody. Our results suggest that the inhibitory tract dissociates from the gamma-subunit in kidneys from rats on a low-Na+ diet. |
