title: The mammalian target of rapamycin signalling pathway is involved in osteoblastic differentiation of vascular smooth muscle cells.
abstract: BACKGROUND
  Vascular calcification is a major risk factor for cardiovascular diseases. Osteoblastic differentiation of vascular smooth muscle cells (VSMCs) is a key step in vascular calcification, but the molecular mechanisms driving the differentiation remain elusive. In this study, the involvement of mammalian target of rapamycin (mTOR) signalling in osteoblastic differentiation of VSMCs is investigated.
  
  
  METHODS
  Calcification of VSMCs was induced in vitro using β-glycerophosphate (β-GP). Real-time polymerase chain reaction was used to measure messenger RNA (mRNA) expression, and Western blot was used to detect protein expression. Inhibition of mTOR expression was established by small interfering RNA (siRNA) and mTOR inhibitors.
  
  
  RESULTS
  The model for osteoblastic differentiation of VSMCs was established in vitro by treating mouse VSMCs with 10 mM β-GP for 3-15 days. Overexpression of mTOR was observed in differentiated VSMCs. Downregulation of mTOR by siRNA or rapamycin significantly inhibited osteoblastic differentiation of VSMCs and decreased the expression and phosphorylation of mTOR and P70 ribosomal S6 kinase in a time- and concentration-dependent manner. Furthermore, adiponectin inhibited the mRNA and protein expression of mTOR in β-GP-treated VSMCs in a time- and concentration-dependent manner.
  
  
  CONCLUSIONS
  mTOR signalling plays a crucial role in the osteoblastic differentiation of VSMCs. Rapamycin and adiponectin might inhibit vascular calcification through regulation of the mTOR pathway.
authors: Department of Geriatrics, Second Xiangya Hospital, Institute of Aging and Geriatrics, Central South University, Changsha, Hunan, P.R. China.
authors: Jun-Kun
authors: JK
authors: Zhan
authors: Department of Geriatrics, Second Xiangya Hospital, Institute of Aging and Geriatrics, Central South University, Changsha, Hunan, P.R. China.
authors: Yan-Jiao
authors: YJ
authors: Wang
authors: Department of Geriatrics, Second Xiangya Hospital, Institute of Aging and Geriatrics, Central South University, Changsha, Hunan, P.R. China.
authors: Yi
authors: Y
authors: Wang
authors: Department of Geriatrics, Second Xiangya Hospital, Institute of Aging and Geriatrics, Central South University, Changsha, Hunan, P.R. China.
authors: Sha
authors: S
authors: Wang
authors: Department of Geriatrics, Second Xiangya Hospital, Institute of Aging and Geriatrics, Central South University, Changsha, Hunan, P.R. China.
authors: Pan
authors: P
authors: Tan
authors: Department of Geriatrics, Second Xiangya Hospital, Institute of Aging and Geriatrics, Central South University, Changsha, Hunan, P.R. China.
authors: Wu
authors: W
authors: Huang
authors: Department of Geriatrics, Second Xiangya Hospital, Institute of Aging and Geriatrics, Central South University, Changsha, Hunan, P.R. China. Electronic address: Liuyoushuo@yeah.net.
authors: You-Shuo
authors: YS
authors: Liu
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000473:pathology*; D010006:Osteoblasts / Q000378:metabolism / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics*; D061205:Vascular Calcification / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology
chemical_list: D007166:Immunosuppressive Agents; D012333:RNA, Messenger; C546843:mTOR protein, mouse; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus