A survey of membrane peptidases in two human colonic cell lines, Caco-2 and HT-29.
The expression of cell-surface peptidases was examined in two human colon carcinoma cell lines, Caco-2 and HT-29. Enzymic assays revealed the presence of eight cell-surface peptidases on a Caco-2 cell line (passage number 82-88), namely aminopeptidase N, dipeptidyl peptidase IV, peptidyl dipeptidase A (angiotension-converting enzyme), aminopeptidase P, aminopeptidase W, endopeptidase-24.11, gamma-glutamyl transpeptidase and membrane dipeptidase. The presence of dipeptidyl peptidase IV and endopeptidase-24.11 was also confirmed immunochemically. After 15 days culture, the activities of aminopeptidase P, peptidyl dipeptidase A and alkaline phosphatase activities on Caco-2 cells reached a plateau, and that of membrane dipeptidase began to decline. In contrast, aminopeptidase N, dipeptidyl peptidase IV and endopeptidase-24.11 activities were still rising after 26 days in culture. Caco-2 cells of passage number 181-183 were found to lack endopeptidase-24.11, but maintained dipeptidyl peptidase IV expression. Two populations of HT-29 cells were surveyed. Both the standard, undifferentiated population and a differentiated population expressed only three peptidases: dipeptidyl peptidase IV, aminopeptidase W and carboxypeptidase M. In the differentiated HT-29 cells the activity of dipeptidyl peptidase IV after 14-21 days was beginning to plateau whereas aminopeptidase W activity was still rising and that of carboxypeptidase M had begun to decline. These differences in activity profiles observed among this group of cell-surface peptidases indicate that these cell lines, especially Caco-2, are useful models to study the regulation of their expression.
Howell
S
S
Department of Biochemistry and Molecular Biology, University of Leeds, U.K.
Kenny
A J
AJ
Turner
A J
AJ
D000626:Aminopeptidases / Q000032:analysis*; D002462:Cell Membrane / Q000201:enzymology; D003106:Colon / Q000201:enzymology*; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D007668:Kidney / Q000201:enzymology; D008871:Microvilli / Q000201:enzymology; D010458:Peptidyl Transferases / Q000378:metabolism; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D014407:Tumor Cells, Cultured
D010458:Peptidyl Transferases; D010727:Phosphoric Diester Hydrolases; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D043265:Phosphatidylinositol Diacylglycerol-Lyase