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This Article Full Text Full Text (PDF) Supplemental Figures All Versions of this Article: 297/3/C611    most recent 00622.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Flores-Benitez, D. Articles by Contreras, R. G. PubMed PubMed Citation Articles by Flores-Benitez, D. Articles by Contreras, R. G.

EXTRACELLULAR MATRIX, CELL INTERACTIONS

Control of tight junctional sealing: roles of epidermal growth factor and prostaglandin E₂

¹Department of Physiology, Biophysics and Neurosciences and ²Department of Pharmacology, Center for Research and Advanced Studies (CINVESTAV), Mexico City, Mexico

Submitted 5 December 2008 ; accepted in final form 25 June 2009

Epithelia can adjust the permeability of the paracellular permeation route by regulating the degree of sealing of the tight junction. This is reflected by a transepithelial electrical resistance (TER) ranging from a few tenths to several thousand ohms times square centimeters, depending on the difference in composition between the fluid in the lumen and the interstitial fluid. Although teleologically sound, such correlation requires a physiological explanation. We have previously shown that urine extracts from different animal species increase the TER of Madin-Darby canine kidney (MDCK) monolayers and that these effects are mediated by epidermal growth factor (EGF) contained in the flowing intratubular fluid that eventually reaches the urine. This increase in TER is accompanied by an enhanced expression of claudin-4 (cln-4) and a decrement of cln-2. These changes are transient, peaking at 16 h and returning to control values in 24 h. In the present work we investigated how EGF provokes this transient response, and we found that the activation of extracellular-regulated kinases 1/2 (ERK1/2) by EGF is essential to increase TER and cln-4 content, but it does not appear to participate in cln-2 downregulation. On the other hand, prostaglandin synthesis, stimulated by EGF, functions as a negative feedback, turning off the signal initiated by EGF. Thus, PGE₂ blocks ERK1/2 by a mechanism that involves the G_s protein, adenylyl cyclase as well as protein kinase A in MDCK cells. In summary, the permeability of a given segment of the nephron depends on the expression of different claudin types, which may be modulated by EGF and prostaglandins.

claudin; cyclooxygenase; extracellular regulated kinase 1/2; forskolin; Madin-Darby canine kidney cell line; transepithelial electrical resistance