title: Core2 O-glycan structure is essential for the cell surface expression of sucrase isomaltase and dipeptidyl peptidase-IV during intestinal cell differentiation.
abstract: Alterations in glycosylation play an important role during intestinal cell differentiation. Here, we compared expression of mucin-type O-glycan synthases from proliferating and differentiated HT-29 and Caco-2 cells. Mucin-type O-glycan structures were analyzed at both stages by mass spectrometry. Core2 β1,6-N-acetylglucosaminyltransferase-2 (C2GnT-2) was markedly increased in differentiated HT-29 and Caco-2 cells, but the core3 structure was hardly detectable. To determine whether such differential expression of mucin-type O-glycan structures has physiological significance in intestinal cell differentiation, expression of sucrase isomaltase (SI) and dipeptidyl-peptidase IV (DPP-IV), two well known intestinal differentiation markers, was examined. Interestingly, the fully glycosylated mature form of SI was decreased in C2GnT-2 knock-out mice but not in core2 N-acetylglucosaminyltransferase-3 (C2GnT-3) nulls. In addition, expression of SI and DPP-IV was dramatically reduced in C2GnT-1-3 triple knock-out mice. These patterns were confirmed by RNAi analysis; C2GnT-2 knockdown significantly reduced cell surface expression of SI and DPP-IV in Caco-2 cells. Similarly, overexpression of the core3 structure in HT-29 cells attenuated cell surface expression of both enzymes. These findings indicate that core3 O-glycan structure regulates cell surface expression of SI and DPP-IV and that core2 O-glycan is presumably an essential mucin-type O-glycan structure found in both molecules in vivo. Finally, goblet cells in the upper part of the crypt showed impaired maturation in the core2 O-glycan-deficient mice. These studies are the first to clearly identify functional mucin-type O-glycan structures modulating cell surface expression of SI and DPP-IV during the intestinal cell differentiation.
authors.affiliation: Glycobiology Unit, Cancer Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA.
authors.forename: Seung Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Shin-Yi
authors.initials: SY
authors.lastname: Yu
authors.forename: Jun
authors.initials: J
authors.lastname: Nakayama
authors.forename: Kai-Hooi
authors.initials: KH
authors.lastname: Khoo
authors.forename: Erica L
authors.initials: EL
authors.lastname: Stone
authors.forename: Michiko N
authors.initials: MN
authors.lastname: Fukuda
authors.forename: Jamey D
authors.initials: JD
authors.lastname: Marth
authors.forename: Minoru
authors.initials: M
authors.lastname: Fukuda
mesh_terms: D000818:Animals; D018938:Caco-2 Cells; D002454:Cell Differentiation; D018819:Dipeptidyl Peptidase 4 / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D006031:Glycosylation; D019073:HT29 Cells; D006801:Humans; D007422:Intestines / Q000737:chemistry / Q000166:cytology* / Q000201:enzymology*; D051379:Mice; D018345:Mice, Knockout; D017351:N-Acetylglucosaminyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013394:Sucrase-Isomaltase Complex / Q000235:genetics / Q000378:metabolism*
chemical_list: D017351:N-Acetylglucosaminyltransferases; C053024:beta-1,3-galactosyl-O-glycosyl-glycoprotein beta-1,6-acetylglucosaminyl transferase; D013394:Sucrase-Isomaltase Complex; D018819:Dipeptidyl Peptidase 4