Paracellular barrier and junctional protein distribution depend on basolateral extracellular Ca 2+ in cultured epithelia

• Published in: Biochimica et biophysica acta. Molecular cell research Vol. 1222; no. 2; pp. 147 - 158
• Main Authors: Collares-Buzato, Carla B., McEwan, Gordon T.A., Jepson, Mark A., Simmons, Nicholas L., Hirst, Barry H.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1994
• Subjects: Cell polarity; Chelation, calcium ion; Desmosome; Paracellular permeability; Zonula adhaerens; Zonula occludens; Zonula adhaerens; Cell polarity; Zonula occludens; Desmosome; Paracellular permeability; Chelation, calcium ion
• ISSN: 0167-4889; 1879-2596
• DOI: 10.1016/0167-4889(94)90163-5

The polarised nature of the increase in paracellular permeability induced by Ca 2+-chelation with EGTA was investigated in several cultured epithelial cell lines. In strain I MDCK cells (canine kidney cells), a marked decrease (> 90%) in transepithelial electrical resistance ( R T) and increase in mannitol and inulin permeabilities were only observed after addition of EGTA (for 4 h) to either basolateral (basal) or both (apical + basal) bathing solutions; apical Ca 2+-chelation resulted in significant smaller changes (∼ 30%) in these variables. The increase in paracellular permeability upon basal EGTA addition was significantly lower than that produced by simultaneous apical and basal addition of 2 mM EGTA. A higher concentration of EGTA (20 mM) did not significantly eliminate this difference in potency between basal and apical + basal Ca 2+-chelation. The polarised Ca 2+-dependence of the paracellular barrier was associated with polarised effects on the junctional/cytoskeletal protein distribution. Basal or apical + basal EGTA addition induced substantial internalisation of uvomorulin with some cellular redistribution of the perijunctional actin ring and desmosomes and gaps in ZO-1 location between adjacent cells. In addition, polarised Ca 2+-dependence of the paracellular barrier (assessed by measuring R T) was observed also in strain II MDCK and two human adenocarcinoma intestinal cell lines, Caco-2 and HCT-8, demonstrating generality of the phenomenon. Therefore, the data show a polarity in the ability of EGTA to enhance epithelial permeability and induce cellular redistribution of cytoskeletal/junctional proteins in several epithelia. The basolateral membrane sensitivity to Ca 2+-chelation might be explained by the polarised distribution of uvomorulin.