Ouabain modulates epithelial cell tight junction.
Epithelial cells treated with high concentrations of ouabain (e.g., 1 microM) retrieve molecules involved in cell contacts from the plasma membrane and detach from one another and their substrates. On the basis of this observation, we suggested that ouabain might also modulate cell contacts at low, nontoxic levels (10 or 50 nM). To test this possibility, we analyzed its effect on a particular type of cell-cell contact: the tight junction (TJ). We demonstrate that at concentrations that neither inhibit K(+) pumping nor disturb the K(+) balance of the cell, ouabain modulates the degree of sealing of the TJ as measured by transepithelial electrical resistance (TER) and the flux of neutral 3 kDa dextran (J(DEX)). This modulation is accompanied by changes in the levels and distribution patterns of claudins 1, 2, and 4. Interestingly, changes in TER, J(DEX), and claudins behavior are mediated through signal pathways containing ERK1/2 and c-Src, which have distinct effects on each physiological parameter and claudin type. These observations support the theory that at low concentrations, ouabain acts as a modulator of cell-cell contacts.
Department of Physiology, Center for Research and Advanced Studies, 07300 Mexico DF, Mexico.
Isabel
I
Larre
Amparo
A
Lazaro
Ruben G
RG
Contreras
Maria S
MS
Balda
Karl
K
Matter
Catalina
C
Flores-Maldonado
Arturo
A
Ponce
David
D
Flores-Benitez
Ruth
R
Rincon-Heredia
Teresita
T
Padilla-Benavides
Aída
A
Castillo
Liora
L
Shoshani
Marcelino
M
Cereijido
D000818:Animals; D000081247:CSK Tyrosine-Protein Kinase; D003911:Dextrans / Q000737:chemistry; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007477:Ions; D008954:Models, Biological; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000737:chemistry; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D015398:Signal Transduction; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D019108:Tight Junctions / Q000187:drug effects*; D019061:src-Family Kinases
D003911:Dextrans; D004791:Enzyme Inhibitors; D007477:Ions; D010042:Ouabain; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium