Localization of epithelial sodium channel subunit mRNAs in adult rat lung by in situ hybridization.
The transport of Na+ through amiloride-sensitive sodium channels (ENaC) plays a major role in the absorption of fluid across the pulmonary epithelium. The proteins forming the ENaC channel are encoded by three genes in the rat (alpha-, beta-, and gamma-rENaC). According to Northern blot, all three subunit mRNAs were expressed in adult rat lung. Each subunit was expressed as a single transcript of approximately 3.7, 2.2, and 3.2 kb for alpha-, beta-, and gamma-rENaC, respectively. To localize the alpha-, beta-, and gamma-rENaC subunit mRNAs, we used in situ hybridization. Frozen and paraffin-embedded tissues were hybridized with sense and antisense 35S-labeled riboprobes. The alpha-rENaC mRNA was most abundant and was expressed diffusely in epithelia of the trachea, bronchi, bronchioles, and alveoli. At the alveolar level, alpha-rENaC was expressed in type II cells. The beta- and gamma-rENaC mRNAs were most abundant in the bronchial and bronchiolar epithelia. All three subunits were expressed in the renal cortical collecting duct in a pattern similar to that previously reported by other investigators. Thus the rENaC subunit mRNAs are expressed in regions of the lung where functional Na+ absorption is found. These results are consistent with an important role for ENaC in the absorption of Na+ and fluid across the pulmonary epithelium in all regions of the lung.
Matsushita
K
K
Department of Internal Medicine, Howard Hughes Medical Institute, University of Iowa College of Medicine, Iowa City 52242, USA.
McCray
P B
PB
Sigmund
R D
RD
Welsh
M J
MJ
Stokes
J B
JB
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D004848:Epithelium / Q000378:metabolism; D017403:In Situ Hybridization; D007668:Kidney / Q000378:metabolism; D008168:Lung / Q000378:metabolism*; D015335:Molecular Probes / Q000235:genetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015222:Sodium Channels / Q000235:genetics*; D014018:Tissue Distribution; D014158:Transcription, Genetic
D015335:Molecular Probes; D012333:RNA, Messenger; D015222:Sodium Channels