抄録
Cry toxins produced by Bacillus thuringiensis are insecticidal toxins and have been recently introduced to genetically modified (GM) organisms. The toxins are considered harmless to humans and farm animals; however, it remains unclear whether the toxins affect the mammalian intestinal epithelium, the primary portal and absorption site after ingestion. Therefore, we performed immunohistochemical and ligand blot analyses using brush border membrane vesicles to investigate the interaction of Cry1Ab toxin, a popular Cry toxin developed in GM corn, with bovine intestinal epithelium, with special attention to the presence of Cry1Ab toxin-binding proteins of the epithelial cell. We found that Cry1Ab toxin binds to actin, a cytoskeletal protein. However, the toxin did not bind to aminopeptidase N, cadherin, or alkaline phosphatase, all of which are cell membrane receptors or candidate proteins necessary for the development of toxicity in susceptible insect cells. The present results and previous observations that Cry toxins have little acute toxicity on mammalian cells indicate that Cry1Ab toxin is able to bind to cytoskeletal actin, but that the bovine intestinal epithelial cell lacks membrane receptors, which are necessary for the toxin to exert its toxicity on the cell.
