title: High glucose potentiates collagen synthesis and bone morphogenetic protein-2-induced early osteoblast gene expression in rat spinal ligament cells.
abstract: Type 2 diabetes mellitus (T2DM) is an independent risk factor for ossification of the posterior longitudinal ligament, but the mechanism is unclear. We isolated cells from rat cervical spine ligaments and studied the effects of high glucose on expression of osteoblast genes to provide insight into molecular mechanism. Using these cells, high glucose stimulated the synthesis of type I collagen and significantly potentiated expression of early osteoblast genes (Runx2; alkaline phosphatase, ALP; and osteopontin, OP) induced by bone morphogenetic protein-2 (BMP-2). Notably, these effects of high glucose were fully mimicked and augmented by H(2)O(2), although blocked by the reactive oxygen species inhibitor N-acetyl cysteine. Furthermore, exposure of these cells to high glucose significantly suppressed the phosphorylation of p38MAPK while enhancing the phosphorylation of protein kinase C (PKC) in the cells. Consistent with these observations, an inhibitor of p38 augmented the potentiation of high glucose on BMP-2-induced early osteogenic gene expression, whereas the PKC inhibitor repressed the effect of high glucose on type I collagen synthesis of the cells. In conclusion, high glucose, via production of reactive oxygen species, subsequent activation of PKC, and inhibition of p38, enhances type I collagen synthesis and expression of early osteogenesis genes induced by BMP-2 in rat spinal ligament cells. Hyperglycemia may play an important role in the onset or progression of ossification of the posterior longitudinal ligament by promoting the responsiveness of ligament cells to osteogenic differentiation.
authors.affiliation: Department of Orthopedic Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 200092 Shanghai, China.
authors.forename: Hai
authors.initials: H
authors.lastname: Li
authors.forename: Lei-Sheng
authors.initials: LS
authors.lastname: Jiang
authors.forename: Li-Yang
authors.initials: LY
authors.lastname: Dai
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics*; D002478:Cells, Cultured; D024042:Collagen Type I / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D017846:Longitudinal Ligaments / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008297:Male; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D010012:Osteogenesis / Q000187:drug effects / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology
chemical_list: D055396:Bone Morphogenetic Protein 2; D024042:Collagen Type I; D017382:Reactive Oxygen Species; D048051:p38 Mitogen-Activated Protein Kinases; D005947:Glucose