title: Expression of ectonucleotide pyrophosphatase-1 in end-plate chondrocytes with transforming growth factor beta 1 siRNA interference by cyclic mechanical tension.
abstract: BACKGROUND
  Ectonucleotide pyrophosphatase/phosphodiesterase (ENPP)-1 is a membrane-bound protein that catalyzes the hydrolysis of extracellular nucleoside triphosphates to monophosphate and extracellular inorganic pyrophosphate (ePPi). Mechanical stimulation regulates ENPP-1 expression. This study sought to investigate the changes in ENPP-1 expression after stimulation using cyclic mechanical tension (CMT).
  
  
  METHODS
  Rat end-plate chondrocytes were cultured and subjected to CMT (at 3%, 6%, and 9% elongation) for 20, 40, and 60 minutes to observe changes in the expression of ENPP-1. To investigate the pathway, end-plate chondrocytes were exposed to 10 ng/ml of transforming growth factor beta 1 (TGF-β1), TGF-β1 siRNA, or a specific extracellular signalregulated kinase (ERK)1/2 inhibitor, U0126, in addition to CMT. Changes in ENPP-1 expression were measured by reverse transcription PCR (RT-PCR) and Western blotting.
  
  
  RESULTS
  We observed the largest increase in ENPP-1 expression following 3% elongation CMT stimulation. ENPP-1 expression was also increased when end-plate chondrocytes were exposed to 10 ng/ml of TGF-β1, but decreased after TGF-β knockdown with siRNA. ERK1/2 phosphorylation was activated after 3% elongation for 40 minutes, and the stimulatory effect of TGF-β1 on ENPP-1 mRNA and protein expression was inhibited by the suppression of the ERK1/2 pathway using U0126.
  
  
  CONCLUSIONS
  CMT increases the expression of ENPP-1 in end-plate chondrocytes in a manner likely dependent on TGF-β induction by the ERK1/2 signaling pathway.
authors.affiliation: Department of Orthopedic Surgery, Yijishan Hospital, Wannan Medical College, Wuhu, Anhui 241001, China (Email: xuhg@medmail.com.cn).
authors.forename: Hong-guang
authors.initials: HG
authors.lastname: Xu
authors.forename: Zi-rui
authors.initials: ZR
authors.lastname: Li
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.forename: Sheng-nan
authors.initials: SN
authors.lastname: Xiang
authors.forename: Chuang-dong
authors.initials: CD
authors.lastname: Wang
authors.forename: Xiao-ling
authors.initials: XL
authors.lastname: Zhang
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism*; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000378:metabolism*; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013314:Stress, Mechanical; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism*
chemical_list: D034741:RNA, Small Interfering; D053773:Transforming Growth Factor beta1; D010727:Phosphoric Diester Hydrolases; C065962:ectonucleotide pyrophosphatase phosphodiesterase 1; D011755:Pyrophosphatases