Figure 6.

Overexpression of claudins-2 and -12 promotes calcium transport in Caco-2 cells. (A) Expression of claudin-2 (Cldn2), Cldn7, and Cldn12 proteins in Caco-2 and Caco-2:Cldn transfectants. Twenty-five micrograms of whole cell extract from the cells was separated by SDS-PAGE and immunoblotted with antibodies against the corresponding claudins, followed by chemiluminescence detection. The blots were stripped and reimmunoprobed with an anti-actin antibody. (B) Staining pattern of Cldn2, Cldn7, and Cldn12 in Caco-2 and Caco-2:Cldn transfectants. Cells were subjected to immunostaining with the corresponding claudin antibodies. Bar, 20 μm. (C and D) Relative levels of TER (C) and ⁴⁵Ca²⁺ transport (D) in Caco-2 and Caco-2:Cldn transfectants. The values of TER and ⁴⁵Ca²⁺ permeability in Caco-2:Cldn transfectants (clones #1 and #2) are expressed relative to the level in the mock-transfected cells, which was taken as 1, and they represent the mean ± SD (error bars; n = 4). *p < 0.05 and **p < 0.01 compared with values of the mock-transfected cells.