title: Leptin promotes the osteoblastic differentiation of vascular smooth muscle cells from female mice by increasing RANKL expression.
abstract: Arterial calcification is a complex and active regulated process, which results from a process of osteoblastic differentiation of vascular smooth muscle cells (VSMCs). Leptin, the product of the ob gene, mainly regulates food intake and energy expenditure and recently has been considered to be correlated with the arterial calcification. However, the mechanisms of the effects of leptin on osteoblastic differentiation of VSMCs are unknown. We used calcifying vascular smooth muscle cells (CVSMCs) as a model to investigate the relationship between leptin and the osteoblastic differentiation of CVSMCs and the signaling pathways involved. Our experiments demonstrated that leptin could increase expression of receptor activator of nuclear factor-κB ligand (RANKL) and bone morphogenetic protein 4 (BMP4), as well as alkaline phosphatase (ALP) activity, runt-related transcription factor 2 expression, calcium deposition, and the formation of mineralized nodules in CVSMCs. Suppression of RANKL with small interfering RNA abolished the leptin-induced ALP activity and BMP4 expression in CVSMCs. Leptin could activate the ERK1/2 and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. Furthermore, pretreatment with the ERK inhibitor PD98059 and the PI3K inhibitor LY294002 abolished leptin-induced RANKL expression and blocked the promotion of ALP activity of CVSMCs. Silencing of the leptin receptor OB-Rb with small interfering RNA abolished leptin-induced activation of ERK and Akt and the expression of RANKL and reversed the effects of leptin on ALP activity. Meanwhile, addition of Noggin (the BMP4 inhibitor) blunted the effect of leptin on ALP activity. These results show that leptin can promote osteoblastic differentiation of CVSMCs by the OB-Rb/ERK1/2/RANKL-BMP4 and OB-Rb/PI3K/Akt/RANKL-BMP4 pathways.
authors.affiliation: Institute of Metabolism and Endocrinology (G.-Y.L., Q.-H.L., R.-R.C., Y.L., S.-S.W., L.-Q.Y., E.-Y.L.), Second Xiang-Ya Hospital, Central S University, Changsha, Hunan, People's Republic of China; and Department of Endocrinology and Metabolism (P.-F.S.), the Second Affiliated Hospital ZheJiang University College of Medicine, Hangzhou, Zhejiang, People's Republic of China.
authors.forename: Guan-Ying
authors.initials: GY
authors.lastname: Liu
authors.forename: Qiu-Hua
authors.initials: QH
authors.lastname: Liang
authors.forename: Rong-Rong
authors.initials: RR
authors.lastname: Cui
authors.forename: Yuan
authors.initials: Y
authors.lastname: Liu
authors.forename: Shan-Shan
authors.initials: SS
authors.lastname: Wu
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Shan
authors.forename: Ling-Qing
authors.initials: LQ
authors.lastname: Yuan
authors.forename: Er-Yuan
authors.initials: EY
authors.lastname: Liao
mesh_terms: D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics / Q000378:metabolism; D002114:Calcinosis / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism; D005260:Female; D020738:Leptin / Q000494:pharmacology*; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D053245:RANK Ligand / Q000235:genetics / Q000378:metabolism*; D054411:Receptors, Leptin / Q000235:genetics / Q000378:metabolism
chemical_list: D055415:Bone Morphogenetic Protein 4; D050659:Core Binding Factor Alpha 1 Subunit; D020738:Leptin; D053245:RANK Ligand; D054411:Receptors, Leptin; C493716:Runx2 protein, mouse; D000469:Alkaline Phosphatase; D002118:Calcium