title: The role of N-glycosylation in high glucose-induced upregulation of intercellular adhesion molecule-1 on bovine retinal endothelial cells.
abstract: OBJECTIVE
  The development of diabetic retinopathy has been implicated as a consequence of chronic inflammation. Given the role of the intercellular adhesion molecule-1 (ICAM-1) in inflammation, the potential effect of N-glycosylation on the upregulated expression of ICAM-1 at the surface of bovine retinal endothelial cells (BRECs) induced by high glucose concentrations was investigated.
  
  
  METHODS
  Gene and protein expression of ICAM-1 in primary BRECs cultured in medium containing increasing concentrations of mannose or glucose in the presence or absence of tunicamycin were studied with reverse transcription-polymerase chain reaction and Western blot analysis, and the expression level of ICAM-1 at the surface of BRECs was examined with an immunofluorescence analysis. A lectin blot assay with PHA-L was performed to explore the level of N-glycans on cell total proteins or immunoprecipitated ICAM-1 from cells treated or untreated with high glucose.
  
  
  RESULTS
  Both the mRNA and protein levels of ICAM-1, as well as the level of ICAM-1 on the cell surface, were significantly upregulated by increasing the concentration of glucose in the culture medium, with a peak concentration of 20 mm. Consistent with these results, a dramatic increase in the N-glycosylation of ICAM-1 in BRECs cultured with a high concentration of glucose was observed, which could be partially attenuated by tunicamycin treatment.
  
  
  CONCLUSIONS
  High glucose-induced upregulation of ICAM-1 on the surface of BRECs could be ascribed to the alterations in its N-glycosylation at least in part, indicating that interference with the glycosylation of ICAM-1 may contribute to improving the efficiency of current therapies with diabetic retinopathy.
authors.affiliation: Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Haiyun
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Ophthalmology, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Ye
authors.affiliation: Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Xun
authors.initials: X
authors.lastname: Xu
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D005947:Glucose / Q000494:pharmacology*; D006031:Glycosylation; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics* / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012171:Retinal Vessels / Q000166:cytology; D015854:Up-Regulation
chemical_list: D011134:Polysaccharides; D012333:RNA, Messenger; D018799:Intercellular Adhesion Molecule-1; D005947:Glucose
keywords: N-glycosylation; high glucose; intercellular adhesion molecule-1