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alpha(1)-Antitrypsin Inhibits Epithelial Na+ Transport In Vitro and In Vivo

Lazrak, Ahmed; Nita, Izabella; Subramaniyam, Devipriya LU ; Wei, Shipeng; Song, Weifeng; Ji, Hong-Long; Janciauskiene, Sabina LU and Matalon, Sadis (2009) In American Journal of Respiratory Cell and Molecular Biology 41(3). p.261-270
Abstract
A variety of studies have shown that Na+ reabsorption across epithelial cells depends on the protease-antiprotease balance. Herein, we investigate the mechanisms by which alpha(1)-antitrypsin (A1AT), a major anti-serine protease in human plasma and lung epithelial fluid and lacking a Kunitz domain, regulates amiloride-sensitive epithelial Na+ channel (ENaC) function in vitro and in vivo. A1AT (0.05 mg/ml = 1 mu M) decreased ENaC currents across Xenopus laevis oocytes injected with human alpha, beta, gamma-ENaC (hENaC) cRNAs, and human lung Clara-like (H441) cells expressing native ENaC, in a partially irreversible fashion. MAT also decreased ENaC single-channel activity when added in the pipette but not in the bath solutions of... (More)
A variety of studies have shown that Na+ reabsorption across epithelial cells depends on the protease-antiprotease balance. Herein, we investigate the mechanisms by which alpha(1)-antitrypsin (A1AT), a major anti-serine protease in human plasma and lung epithelial fluid and lacking a Kunitz domain, regulates amiloride-sensitive epithelial Na+ channel (ENaC) function in vitro and in vivo. A1AT (0.05 mg/ml = 1 mu M) decreased ENaC currents across Xenopus laevis oocytes injected with human alpha, beta, gamma-ENaC (hENaC) cRNAs, and human lung Clara-like (H441) cells expressing native ENaC, in a partially irreversible fashion. MAT also decreased ENaC single-channel activity when added in the pipette but not in the bath solutions of ENaC-expressing oocytes patched in the cell-attached mode. Incubation of A1AT with peroxynitrite (ONOO-), an oxidizing and nitrating agent, abolished its antiprotease activity and significantly decreased its ability to inhibit ENaC. Intratracheal instillation of normal but not ONOO--treated A1AT (1 mu M) in C57BL/6 mice also decreased Na+-dependent alveolar fluid clearance to the same level as amiloride. Incubation of either H441 cells or ENaC-expressing oocytes with normal but not ONOO--treated MAT decreased their ability to cleave a substrate of serine proteases. A1AT had no effect on amiloride-sensitive currents of oocytes injected with hENaC bearing Liddle mutations, presumably because these channels remain at the surface longer than the wild-type channels. These data indicate that MAT may be an important modulator of ENaC activity and of Na+-dependent fluid clearance across the distal lung epithelium in vivo by decreasing endogenous protease activity needed to activate silent ENaC. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Xenopus, H441 cells, alveolar fluid clearance, serine proteases, oocytes, ENaC
in
American Journal of Respiratory Cell and Molecular Biology
volume
41
issue
3
pages
261 - 270
publisher
American Thoracic Society
external identifiers
  • wos:000269346400002
  • scopus:69449099515
ISSN
1535-4989
DOI
10.1165/rcmb.2008-0384OC
language
English
LU publication?
yes
id
e738c0f1-0dc6-432c-87ae-6d169038758a (old id 1476836)
date added to LUP
2009-09-28 10:51:50
date last changed
2017-08-27 03:52:14
@article{e738c0f1-0dc6-432c-87ae-6d169038758a,
  abstract     = {A variety of studies have shown that Na+ reabsorption across epithelial cells depends on the protease-antiprotease balance. Herein, we investigate the mechanisms by which alpha(1)-antitrypsin (A1AT), a major anti-serine protease in human plasma and lung epithelial fluid and lacking a Kunitz domain, regulates amiloride-sensitive epithelial Na+ channel (ENaC) function in vitro and in vivo. A1AT (0.05 mg/ml = 1 mu M) decreased ENaC currents across Xenopus laevis oocytes injected with human alpha, beta, gamma-ENaC (hENaC) cRNAs, and human lung Clara-like (H441) cells expressing native ENaC, in a partially irreversible fashion. MAT also decreased ENaC single-channel activity when added in the pipette but not in the bath solutions of ENaC-expressing oocytes patched in the cell-attached mode. Incubation of A1AT with peroxynitrite (ONOO-), an oxidizing and nitrating agent, abolished its antiprotease activity and significantly decreased its ability to inhibit ENaC. Intratracheal instillation of normal but not ONOO--treated A1AT (1 mu M) in C57BL/6 mice also decreased Na+-dependent alveolar fluid clearance to the same level as amiloride. Incubation of either H441 cells or ENaC-expressing oocytes with normal but not ONOO--treated MAT decreased their ability to cleave a substrate of serine proteases. A1AT had no effect on amiloride-sensitive currents of oocytes injected with hENaC bearing Liddle mutations, presumably because these channels remain at the surface longer than the wild-type channels. These data indicate that MAT may be an important modulator of ENaC activity and of Na+-dependent fluid clearance across the distal lung epithelium in vivo by decreasing endogenous protease activity needed to activate silent ENaC.},
  author       = {Lazrak, Ahmed and Nita, Izabella and Subramaniyam, Devipriya and Wei, Shipeng and Song, Weifeng and Ji, Hong-Long and Janciauskiene, Sabina and Matalon, Sadis},
  issn         = {1535-4989},
  keyword      = {Xenopus,H441 cells,alveolar fluid clearance,serine proteases,oocytes,ENaC},
  language     = {eng},
  number       = {3},
  pages        = {261--270},
  publisher    = {American Thoracic Society},
  series       = {American Journal of Respiratory Cell and Molecular Biology},
  title        = {alpha(1)-Antitrypsin Inhibits Epithelial Na+ Transport In Vitro and In Vivo},
  url          = {http://dx.doi.org/10.1165/rcmb.2008-0384OC},
  volume       = {41},
  year         = {2009},
}