title: N-acetylglucosaminyltransferase V negatively regulates integrin α5β1-mediated             monocyte adhesion and transmigration through vascular endothelium.
abstract: Changes in the expression of glycosyltransferases that branch N-linked glycans are associated with many physiological and pathological events, such as cell adhesion, migration, proliferation and tumor cell malignancy. Here, the altered levels of N-acetylglucosaminyltransferase V (GnT-V) and its product β(1,6)-linked GlcNAc in monocytes were observed during inflammation. The effects of GnT-V and aberrant N-linked β(1,6) branching on monocyte adhesion through vascular endothelium and transmigration were investigated. During IFN-γ-induced inflammation, adhesion and transendothelial migration of THP-1 monocytes were enhanced, and the levels of GnT-V and β(1,6)-linked GlcNAc in THP-1 monocytes were significantly decreased. Expression of the GnT-V shRNA vector in THP-1 cells reversed the abnormal IFN-γ-induced characteristics, indicating direct involvement of N-glycosylation in these biological effects. The enhanced adhesion and transendothelial migration were significantly inhibited by functional blockade with antibodies against integrin α5 or β1 in IFN-γ-induced and GnT-V knockdown THP-1 cells, demonstrating the involvement of integrin α5β1 in the monocyte-endothelium interaction. However, IFN-γ treatment and GnT-V knockdown in THP-1 cells lowered expression of N-linked β(1,6) branching on integrin α5 and β1, without affecting the total protein expression of the subunits. Decreased GnT-V expression caused marked enchancement of integrin-induced phosphorylation of focal adhesion kinase (FAK). The augmented FAK-mediated ERK phosphorylation and activation were observed in IFN-γ-induced THP-1 cells. Furthermore, ERK inhibitor pre-treatment nearly abrogated the highly elevated IFN-γ-induced monocyte adhesion and transmigration, concomitant with reversal of the decrease in GnT-V and β(1,6) branching. Our results demonstrate for the first time that decreased GnT-V activity due to inflammatory cytokine induction in human monocytes resulted in enchancement of integrin α5β1-dependent monocyte-vascular endothelium adhesion and transmigration. Consequently, the activation of integrin caused elevation of FAK phosphorylation. These effects promoted FAK-mediated downstream signaling, including the ERK pathway, and indicate that GnT-V may be a potential therapeutic target for vascular inflammatory conditions.
authors.affiliation: Department of Obstetrics and Gynecology, Chongqing Medical University, Chongqing, Chongqing, People's Republic of China.
authors.forename: Huo-Mei
authors.initials: HM
authors.lastname: Yang
authors.forename: Chao
authors.initials: C
authors.lastname: Yu
authors.forename: Zhu
authors.initials: Z
authors.lastname: Yang
mesh_terms: D002448:Cell Adhesion; D045744:Cell Line, Tumor; D015536:Down-Regulation; D004730:Endothelium, Vascular; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006031:Glycosylation; D006801:Humans; D018836:Inflammation Mediators / Q000502:physiology; D039081:Integrin alpha5beta1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007371:Interferon-gamma / Q000502:physiology; D009000:Monocytes / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D034622:RNA Interference; D057705:Transendothelial and Transepithelial Migration
chemical_list: D005419:Flavonoids; D018836:Inflammation Mediators; D039081:Integrin alpha5beta1; D007371:Interferon-gamma; D017351:N-Acetylglucosaminyltransferases; C052254:alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; D048049:Extracellular Signal-Regulated MAP Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one