title: Tumor necrosis factor-alpha increases alkaline phosphatase expression in vascular smooth muscle cells via MSX2 induction.
abstract: Vascular calcification is implicated in many diseases including atherosclerosis and diabetes. Tumor necrosis factor-alpha (TNF-alpha) has been shown to promote vascular calcification both in vitro and in vivo. However, the molecular mechanism of TNF-alpha-mediated vascular calcification has not yet been fully defined. Therefore, in this study, we aimed to investigate whether MSX2 acts as a crucial regulator in TNF-alpha-induced vascular calcification and to define the regulatory mechanism of MSX2 induction in human vascular smooth muscle cells (VSMCs). TNF-alpha increased the expression of osteogenic marker genes including RUNX2, osterix, alkaline phosphatase (ALP), and bone sialoprotein, and it also promoted matrix mineralization in VSMCs. In addition, TNF-alpha enhanced MSX2 expression in a dose- and time-dependent manner. MSX2 over-expression alone induced ALP expression, whereas knockdown of MSX2 with small interfering RNA completely blocked TNF-alpha-induced ALP expression. New protein synthesis was dispensable for MSX2 induction by TNF-alpha, and the inhibition of NF-kappaB by BAY-11-7082 or by dominant negative IkappaBalpha abolished the TNF-alpha-directed induction of MSX2 expression. However, inhibition of NADPH oxidase did not affect MSX2 expression. In conclusion, our study suggests that TNF-alpha directly induces MSX2 expression through the NF-kappaB pathway, which in turn induces expression of ALP, a key molecule in mineralization, in VSMCs.
authors.affiliation: Department of Cell and Developmental Biology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea.
authors.forename: Hye-Lim
authors.initials: HL
authors.lastname: Lee
authors.forename: Kyung Mi
authors.initials: KM
authors.lastname: Woo
authors.forename: Hyun-Mo
authors.initials: HM
authors.lastname: Ryoo
authors.forename: Jeong-Hwa
authors.initials: JH
authors.lastname: Baek
mesh_terms: D000469:Alkaline Phosphatase / Q000096:biosynthesis*; D002114:Calcinosis / Q000378:metabolism*; D002478:Cells, Cultured; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology; D016328:NF-kappa B / Q000378:metabolism; D010012:Osteogenesis; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D018398:Homeodomain Proteins; C084119:MSX2 protein; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D000469:Alkaline Phosphatase