N-Terminal Truncation of TACO Inhibits PMA-Induced U937 Cell Adhesion

The effect of TACO 1-299, the N-terminal truncation of TACO, on phorbol 12-myristate 13-acetate (PMA)-induced U937 cell adhesion was investigated. Full-length TACO and several truncations were overexpressed in U937 cells. The effects of the expressed proteins on U937 cell adhesion mediated by PMA-induced differentiation were observed by fluorescence microscopy. The results show that the overexpression of TACO 1-299 inhibits cell adhesion while overexpressions of the other proteins do not have this effect. The actin-binding capability of TACO 1-299 was investigated and the results show that TACO 1-299 lacks the ability of TACO to bind F-actin. The inhibitive effect of TACO 1-299, the functional domain of TACO, suggests that TACO may play a role in cell differentiation mediating adhesion of monoblastic leukemia cells.