Transient expression of polymeric immunoglobulin receptor in human adenocarcinoma cell line HT-29.

Human polymeric immunoglobulin receptor (pIgR) protein was expressed in the adeno-carcinoma cell line HT-29 using a recombinant vaccinia virus transfection method. The pIgR protein was detected as 110- and 120-kDa bands by immunoprecipitation after metabolic labeling. PIgR was released as a free secretory component into the culture supernatant and was detected as a 110-kDa band. PIgR cleavage was investigated by adding the proteinase inhibitor leupeptin or protein kinase C activator PMA. Consistent with previous observations in the Madin Darby canine kidney cell system, cleavage of pIgR was inhibited by leupeptin and enhanced by PMA stimulation, thus indicating that it is regulated by common mechanisms. This experimental system should be very useful for pIgR investigation.