title: Mucin biosynthesis: upregulation of core 2 beta 1,6 N-acetylglucosaminyltransferase by retinoic acid and Th2 cytokines in a human airway epithelial cell line.
abstract: Vitamin A and the T helper 2 cytokines IL-4 and IL-13 play important roles in the induction of mucin gene expression and mucus hypersecretion. However, the effects of these agents on enzymes responsible for mucin glycosylation have received little attention. Here, we report the upregulation of core 2 beta1,6 N-acetylglucosaminyltransferase (C2GnT) activity both by all-trans retinoic acid (RA) and by IL-4 and IL-13 in the H292 airway epithelial cell line. Northern blotting analysis showed that the M isoform of C2GnT, which is expressed in mucus-secreting tissues and can form all mucin glycan beta1,6-branched structures, including core 2, core 4, and blood group I antigen, was upregulated by both RA and IL-4/13. The L isoform, which forms only the core 2 structure, was moderately upregulated by IL-4/13 but not by RA. Enhancement of the M isoform of C2GnT by RA was abolished by an inhibitor of RA receptor alpha, implicating RA receptor alpha in the effect of RA. Likewise, an inhibitor of the Janus kinase 3 pathway blocked the enhancing effects of IL-4/13 on the L and M isoforms of C2GnT, suggesting a role of this pathway in the upregulation of these two C2GnTs by these cytokines. Taken together, the results suggest that IL-4/13 T helper 2 cytokines and RA can alter the activity of enzymes that synthesize branching mucin carbohydrate structure in airway epithelial cells, potentially leading to altered mucin carbohydrate structure and properties.
authors.affiliation: Dept. of Biochemistry and Molecular Biology, The Nebraska Medical Center, Omaha, NE 68198-5870, USA
authors.forename: Paul V
authors.initials: PV
authors.lastname: Beum
authors.forename: Hesham
authors.initials: H
authors.lastname: Basma
authors.forename: Dhundy R
authors.initials: DR
authors.lastname: Bastola
authors.forename: Pi-Wan
authors.initials: PW
authors.lastname: Cheng
mesh_terms: D002460:Cell Line; D006801:Humans; D018793:Interleukin-13 / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology*; D055271:Mucin 5AC; D009077:Mucins / Q000096:biosynthesis* / Q000378:metabolism; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012137:Respiratory System / Q000378:metabolism*; D015398:Signal Transduction; D014212:Tretinoin / Q000494:pharmacology*; D015854:Up-Regulation
chemical_list: D018793:Interleukin-13; C524678:MUC5AC protein, human; D055271:Mucin 5AC; D009077:Mucins; D012333:RNA, Messenger; D015847:Interleukin-4; D014212:Tretinoin; D017351:N-Acetylglucosaminyltransferases; C476018:core 4 beta1,6 N-acetylglucosaminyltransferase, human