title: Transforming growth factor-beta 1 increases lysyl oxidase enzyme activity and mRNA in rat aortic smooth muscle cells.
abstract: OBJECTIVE
  This investigation was designed to test the hypothesis that transforming growth factor-beta 1 (TGF-beta 1) regulates lysyl oxidase secretion from vascular smooth muscle cells. Lysyl oxidase is an enzyme that catalyzes an essential step in collagen and elastin cross-linking in the extracellular matrix, and TGF-beta 1 has been implicated in the pathogenesis of restenosis after vascular injury. The effect of TGF-beta 1 on lysyl oxidase in vascular smooth muscle cells has not been previously defined.
  
  
  METHODS
  Rat aortic smooth muscle cells were grown in culture to confluence. Cells in passage 2 to 6 were incubated for 24 hours in media containing 0.1, 0.5, 1.0, or 10.0 ng/ml of TGF-beta 1. Lysyl oxidase activity in the media was quantitated with a tritium-release bioassay against an insoluble 3H-labeled aortic clastin substrate. Northern blot analyses were performed to determine steady-state levels of lysyl oxidase mRNA in the smooth muscle cells.
  
  
  RESULTS
  Lysyl oxidase activity in the media increased 1.5-fold above control levels after exposure to 10 ng/ml of TGF-beta 1 (p < 0.01). This increase in lysyl oxidase activity was associated with a concentration-dependent increase in steady-state levels of lysyl oxidase mRNA, being 4.3- and 6.2-fold above control levels after exposure to 1 and 10 ng/ml TGF-beta 1, respectively (p < 0.01). The observed increase in steady-state lysyl oxidase mRNA after exposure to TGF-beta 1 was also time-dependent over the 24-hour experimental period.
  
  
  CONCLUSIONS
  TGF-beta 1 appears to regulate lysyl oxidase in cultured rat aortic smooth muscle cells. Increases in lysyl oxidase activity may be one of the mechanisms by which TGF-beta 1 contributes to arterial restenosis after vascular injury.
authors.affiliation: Department of Surgery, Jobst Laboratories, University of Michigan Medical School, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Shanley
authors.forename: M
authors.initials: M
authors.lastname: Gharaee-Kermani
authors.forename: R
authors.initials: R
authors.lastname: Sarkar
authors.forename: T H
authors.initials: TH
authors.lastname: Welling
authors.forename: A
authors.initials: A
authors.lastname: Kriegel
authors.forename: J W
authors.initials: JW
authors.lastname: Ford
authors.forename: J C
authors.initials: JC
authors.lastname: Stanley
authors.forename: S H
authors.initials: SH
authors.lastname: Phan
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000201:enzymology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000201:enzymology*; D008249:Protein-Lysine 6-Oxidase / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016212:Transforming Growth Factor beta / Q000494:pharmacology* / Q000502:physiology
chemical_list: D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D008249:Protein-Lysine 6-Oxidase