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ENaC and CFTR relocate between caveoli and cell membrane during late gestation in fetal guinea pig lungs
Author(s) -
Beard LaMonta L.,
Li Tianbo,
Hu Yang,
Trimble George L.,
Folkesson Hans G.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1340-c
Subject(s) - epithelial sodium channel , secretion , lung , fetus , medicine , endocrinology , guinea pig , biology , apical membrane , chemistry , microbiology and biotechnology , andrology , membrane , sodium , pregnancy , biochemistry , genetics , organic chemistry
Our goal was to study the role of caveoli in ENaC and CFTR membrane distribution near term. Our hypothesis was that ENaC is in caveoli and CFTR in membrane when the epithelium secretes fluid and ENaC is in the membrane and CFTR is in caveoli during fluid absorption and this configuration causes net distal lung fluid absorption in preterm guinea pigs. To test our hypothesis we separated caveoli in the membrane by sucrose gradient separation. Twelve fractions ( F ) were obtained, F5‐8 represent caveoli and F9‐12 cell membrane. Caveolar marker was caveolin‐1 ( Cav‐1 ) and membrane marker was PMCA. Western blots confirmed Cav‐1 and PMCA in F5‐8 and F9‐12, respectively. There was F5‐8 ENaC localization at 61 days ( GD ) gestation. At GD68, ENaC localized to F9‐12. CFTR localized to F9‐12 at GD61 and to F5‐8 at GD68. Induction of lung maturation by maternal IL‐1β at GD61 resulted in ENaC in F9‐12 and CFTR in F5‐8. To confirm our observations, we instilled GD61 and GD68 fetuses with the caveoli disrupting agent, methyl‐β‐cyclodextrin ( M β CD ). MβCD instillation mimicked ENaC expression after IL‐1β. F5 co‐IP of Cav‐1 with ENaC decreased and Cav‐1 with CFTR increased as term neared and with IL‐1β. These results provide novel molecular mechanisms that may explain the rapid lung fluid secretion to absorption transition near‐term and after maternal IL‐1β. ( Funded by March of Dimes Birth Defects Foundation Research Grant No. 6‐FY03‐64 )