Figure 1.

CD46 interacts with and/or modulates expression of proteins required for intestinal epithelial cell layer integrity. (A,B) CD46 associates with SPAK and E-cadherin in human colon epithelial cells. Caco-2 cells were activated for 3 h by receptor cross-linking using the antibodies indicated, and cell lysates used for immunoprecipitation with a CD46-specific or isotype control mAb. Immunoblotting with an anti-CD46 mAb assessed successful precipitation while anti-SPAK, anti-α-E-catenin, and anti-E-cadherin antibodies revealed an association between CD46 and SPAK and CD46 and E-cadherin. Untreated lysates from non-activated cells were loaded as control (“lysate”). Data are representative of three similarly performed experiments. (C) CD46 activation increases E-cadherin expression in Caco-2 cells. Caco-2 cells were either left non-activated or activated as described under (A) (but for 12 h) and E-cadherin expression levels determined via FACS analysis. CD46 activation did not modulate α-E-catenin or SPAK expression levels (data not shown). FACS plot shown is representative of three separately but similarly performed experiments. (D) CD46 activation of Caco-2 cells induces rapid CD46 downregulation. Caco-2 cells were activated as indicated and CD46 expression levels measured at 2, 4, and 24 h post activation. Data represent mean ± SD (n = 3). NA, non-activated.