ISSN:
0730-2312
Keywords:
β1→3N-acetylglucosaminyltransferase
;
cancer-associated carbohydrate antigens
;
biosynthesis
;
glycosphingolipid
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Human colonic adenocarcinoma DLD-1 cells were grown under conditions which induce characteristics of differentiated cells using medium containing 0.8% N,N-dimethylformamide in order to study alterations in glycosphingolipid glycosyltransferase activities during this process. Analysis of biosynthetic reactions involved in lacto-series antigen synthesis revealed no changes in the specific activities of either β1→4galactosyltransferase or α1→3/4fucosyltransferase with N,N-dimethylformamide treatment. However, a dramatic decrease of from 14- to 20-fold in the β1→3N-acetylglucosaminyltransferase activity was observed in the treated cells. This enzyme catalyzes the rate-limiting step in lacto-series core chain synthesis. This is consistent with the pattern of regulation of lacto-series antigen expression found to occur during oncogenesis in human colonic mucosa (Holmes EH, Hakomori S, Ostrander GK: J Biol Chem 262:15649, 1987). Total glycolipids from untreated and N,N-dimethylformamide-treated cells were isolated and subjected to TLC immunostain analysis and solid phase radioimmunoassay with a series of monoclonal antibodies specific for lacto-series-based carbohydrate antigens. A decrease of about 2-fold or less in the quantity of lacto-series antigens was observed as a consequence of N,N-dimethylformamide treatment in both neutral glycolipid and ganglioside fractions. The results suggest that only very low levels of β1→3N-acetylglucosaminyltransferase activity are required for the steady state expression of significant levels of lacto-series based glycolipids and that modulation of its activity levels by N,N-dimethylformamide treatment in DLD-1 cells represents a convenient in vitro system for studying aspects of regulation of lacto-series antigen expression.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcb.240440204
Permalink
