Inhibition of the post‐translational processing of microvillar hydrolases is associated with a specific decreased expression of sucrase‐isomaltase and an increased turnover of glucose in Caco‐2 cells treated with monensin

Abstract

The biosynthesis and post‐translational processing of sucrase‐isomaltase and dipeptidylpeptidase IV were studied by L‐[35S]methionine labeling, immunoisolation with monoclonal antibodies and SDS‐PAGE in post‐confluent Caco‐2 cells treated with monensin (10 μM, 48 h). In addition to its classical effect on the post‐translational processing of both hydrolases, i.e. an inhibition of the conversion of the high‐mannose to the complex glycosylated form of the enzymes, monensin was found to have two other effects: a marked decrease of sucrase‐isomaltase expression, but not of dipeptidylpeptidase IV; an increased turnover of glucose, as substantiated by increased rates of glucose consumption and lactic acid production and a decreased glycogen content. Whether these two effects are related to the particular differentiation and metabolic status of Caco‐2 cells is discussed, as well as a possible role for the drug‐induced modifications of glucose turnover on the decreased expression of sucrase‐isomaltase.

Expression of dipeptidyl aminopeptidase IV during enterocytic differentiation of human colon cancer (Caco‐2) cells

“…The enzyme had a molecular mass of approximately 115 kDa, and was found primarily associated with the cell-membrane fraction. These observations are in general agreement with those of other investigators who have used the Caco-2 cell line in their studies (Hauri et al, 1985;Rousset et al, 1986;Steiger et al, 1988;Matter et al, 1989).…”

“…At the present time, the reasons for this are unknown; however, similar studies with alkaline phosphatase reveal no differences in processing time for this particular enzyme (Matsumoto et al, 1990). Conversely, other studies have shown that there are differences in the processing time for different brush-border-membrane hydrolases, with the peptidases being processed at a faster rate than the disaccharidases in differentiated Caco-2 cells (Rousset et al, 1986;Steiger et al, 1988).…”

Pathogenesis of Human Enterovirulent Bacteria: Lessons from Cultured, Fully Differentiated Human Colon Cancer Cell Lines

“…In addition, a subapical cell compartment seems to function as a docking platform for vesicles containing functional proteins (98). Parental Caco-2 cells and clones have also been used to identify the mechanisms underlying the sorting and surface delivery of apical and basolateral proteins in human enterocytes (99)(100)(101)(102)(103)(104)(105)(106)(107) and to find out how functional intestinal proteins take their place in cell membrane domains, including brush border-associated functional proteins such as SI (82,84,86,90,94,100,106,(108)(109)(110)(111)(112)(113)(114), AP (110,111), lactasephlorizin hydrolase (108,115), maltase-glucoamylase (108), APN (90,108,111), DPP IV (82,90,100,108,(116)(117)(118)(119)(120)(121), angiotensin I-converting enzyme (108), ␣-glucosidase (122), p-aminobenzoic acid peptide hydrolase (108), SGLT1, GLUT1, GLUT2, GLUT3, and GLUT5 (123)(124)…”

Enhanced Microscopic Definition of Campylobacter jejuni 81-176 Adherence to, Invasion of, Translocation across, and Exocytosis from Polarized Human Intestinal Caco-2 Cells

“…During 7 to 10 days in culture, these cells form polarized monolayers that have intercellular tight junctions and defined apical and basolateral surfaces. The differentiated apical surface has dense brush border microvilli containing normal intestinal brush border enzymes and antigens (13,18,43,44). A key advantage of differentiated Caco-2 cells is that they provide a substrate monolayer similar to that for which Campylobacter shows a natural tropism in vivo.…”