The transport of vitamin B12 through polarized monolayers of Caco-2 cells.
Caco-2 cells grown on 0.45-micron filters, in Millicell chambers, form intact monolayers with many of the properties of polarized intestinal epithelial cells. It is reported here that these cells bind and internalize intrinsic factor-cobalamin complexes and that after 14-28 days in culture this specific binding is exclusively located on the apical membrane. Caco-2 cells also synthesize and secrete a protein with properties similar to transcobalamin II. This protein is secreted from the basolateral side of the cells after 20 days in culture. Specific apical-to-basolateral transcellular transport of [57Co]cobalamin also occurs between 20 and 28 days in culture. Thus, Caco-2 cells provide the first polarized human cell system for studying the transepithelial transport of cobalamin.
Dix
C J
CJ
Advanced Drug Delivery Research Unit, Ciba-Geigy Pharmaceuticals, Horsham, West Sussex, United Kingdom.
Hassan
I F
IF
Obray
H Y
HY
Shah
R
R
Wilson
G
G
D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002277:Carcinoma / Q000378:metabolism* / Q000648:ultrastructure; D002461:Cell Line, Transformed; D002852:Chromatography, Ion Exchange / Q000379:methods; D003106:Colon / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000648:ultrastructure; D004553:Electric Conductivity; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D007437:Intrinsic Factor / Q000187:drug effects / Q000378:metabolism; D008854:Microscopy, Electron; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D013997:Time Factors; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D014805:Vitamin B 12 / Q000378:metabolism*
D007437:Intrinsic Factor; D014805:Vitamin B 12