title: Metabolic homeostasis and tissue renewal are dependent on beta1,6GlcNAc-branched N-glycans.
abstract: Golgi beta1,6-N-acetylglucosaminyltransferase V (Mgat5) produces beta1,6GlcNAc-branched N-glycans on glycoproteins, which increases their affinity for galectins and opposes loss from the cell surface to constitutive endocytosis. Oncogenic transformation increases Mgat5 expression, increases beta1,6GlcNAc-branched N-glycans on epidermal growth factor and transforming growth factor-beta receptors, and enhances sensitivities to ligands, cell motility, and tumor metastasis. Here, we demonstrate that Mgat5(-/-) mouse embryonic fibroblasts (MEFs) display reduced sensitivity to anabolic cytokines and reduced glucose uptake and proliferation. Mgat5(-/-) mice are also hypoglycemic, resistant to weight gain on a calorie-enriched diet, hypersensitive to fasting, and display increased oxidative respiration and reduced fecundity. Serum-dependent activation of the extracellular response kinase (growth) and Smad2/3 (arrest) pathways in Mgat5(-/-) MEFs and bone marrow cells reveals an imbalance favoring arrest. Mgat5(-/-) mice have fewer muscle satellite cells, less osteogenic activity in bone marrow, and accelerated loss of muscle and bone mass with aging. Our results suggest that beta1,6GlcNAc-branched N-glycans promote sensitivity to anabolic cytokines, and increase fat stores, tissue renewal, and longevity.
authors.affiliation: Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue R988, Toronto, ON, Canada M5G 1X5.
authors.forename: Pam
authors.initials: P
authors.lastname: Cheung
authors.forename: Judy
authors.initials: J
authors.lastname: Pawling
authors.forename: Emily A
authors.initials: EA
authors.lastname: Partridge
authors.forename: Balram
authors.initials: B
authors.lastname: Sukhu
authors.forename: Marc
authors.initials: M
authors.lastname: Grynpas
authors.forename: James W
authors.initials: JW
authors.lastname: Dennis
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism; D002478:Cells, Cultured; D005947:Glucose / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D006031:Glycosylation; D006706:Homeostasis; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D017351:N-Acetylglucosaminyltransferases / Q000737:chemistry / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D013997:Time Factors
chemical_list: D006023:Glycoproteins; D011134:Polysaccharides; D017351:N-Acetylglucosaminyltransferases; C052254:alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase; D005947:Glucose