Effects of transdifferentiation and EGF on claudin isoform expression in alveolar epithelial cells.
Rat alveolar epithelial type II cells grown on polycarbonate filters form high-resistance monolayers and concurrently acquire many phenotypic properties of type I cells. Treatment with EGF has previously been shown to increase transepithelial resistance across alveolar epithelial cell (AEC) monolayers. We investigated changes in claudin expression in primary cultured AEC during transdifferentiation to the type I cell-like phenotype (days 0, 1, and 8), and on day 5 in culture +/- EGF (10 ng/ml) from day 0 or day 4. Claudins 4 and 7 were increased, whereas claudins 3 and 5 were decreased, on later compared with earlier days in culture. Exposure to EGF led to increases in claudins 4 and 7 and decreases in claudins 3 and 5. Claudin 1 was only faintly detectable in freshly isolated type II cells and remained unchanged over time in culture and after exposure to EGF. These results suggest that increases in transepithelial resistance accompanying AEC transdifferentiation and/or EGF exposure are mediated, at least in part, by changes in the pattern of expression of specific claudin isoforms.
Chen
Stephen P
SP
Division of Pulmonary and Critical Care Medicine, University of Southern California, IRD 260, 2020 Zonal Avenue, Los Angeles, CA 90033, USA.
Zhou
Beiyun
B
Willis
Brigham C
BC
Sandoval
Argelia J
AJ
Liebler
Janice M
JM
Kim
Kwang-Jin
KJ
Ann
David K
DK
Crandall
Edward D
ED
Borok
Zea
Z
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D010641:Phenotype; D020033:Protein Isoforms / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000166:cytology* / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure
D008565:Membrane Proteins; D020033:Protein Isoforms; D004815:Epidermal Growth Factor