Swainsonine is a useful tool to monitor the intracellular traffic of N-linked glycoproteins as a function of the state of enterocytic differentiation of HT-29 cells.
After treatment with swainsonine, an inhibitor of both lysosomal alpha-mannosidase and Golgi alpha-mannosidase-II activities, analysis of [3H]mannose-labeled glycans showed that HT-29 cells, derived from a human colonic adenocarcinoma, displayed distinct patterns of N-glycan expression, depending upon their state of enterocytic differentiation. In differentiated HT-29 cells hybrid-type chains were detected, whereas undifferentiated HT-29 cells accumulated high-mannose-type oligosaccharide, despite our demonstration of Golgi alpha-mannosidase-II activity in both cell populations. Pulse/chase experiments carried out in the presence of swainsonine revealed that the persistence of high-mannose-type chains in undifferentiated HT-29 cells was the result of the stabilization of glycoproteins substituted with these glycans. These data suggest that in undifferentiated HT-29 cells, glycoproteins with high-mannose-type oligosaccharides are delivered to a degradative compartment containing swainsonine-sensitive alpha-mannosidase(s), whereas in differentiated HT-29 cells glycoproteins enter a compartment in which alpha-mannosidase II (Golgi apparatus) is present. Thus, this apparent dual effect of swainsonine on N-glycan trimming may reflect differences in the intracellular traffic of glycoproteins as a function of the state of enterocytic differentiation of HT-29 cells.
Houri
J J
JJ
Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 180, Université René Descartes, Paris, France.
Ogier-Denis
E
E
Bauvy
C
C
Aubery
M
M
Sapin
C
C
Trugnan
G
G
Codogno
P
P
D000230:Adenocarcinoma / Q000473:pathology; D002454:Cell Differentiation; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D003110:Colonic Neoplasms / Q000473:pathology; D006023:Glycoproteins / Q000378:metabolism*; D006056:Golgi Apparatus / Q000201:enzymology; D006801:Humans; D008247:Lysosomes / Q000201:enzymology; D008361:Mannosidases / Q000037:antagonists & inhibitors; D011134:Polysaccharides / Q000378:metabolism; D017026:Swainsonine / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects*; D043323:alpha-Mannosidase
D006023:Glycoproteins; D011134:Polysaccharides; D008361:Mannosidases; D043323:alpha-Mannosidase; D017026:Swainsonine