title: Transforming growth factor-β1 involved in urotensin II-induced phenotypic differentiation of adventitial fibroblasts from rat aorta.
abstract: BACKGROUND
  Urotensin II (UII) is a new vasoconstrictive peptide that may activate the adventitial fibroblasts. Transforming growth factor-β1 (TGF-β1) is an important factor that could induce the phenotypical transdifferentiation of adventitial fibroblasts. This study aimed to explore whether TGF-β1 is involved in UII-induced phenotypic differentiation of adventitial fibroblasts from rat aorta.
  
  
  METHODS
  Adventitial fibroblasts were prepared by the explant culture method. TGF-β1 protein secretion from the cells was determined by enzyme-linked immunosorbent assay (ELISA). The mRNA and protein expression of α-smooth nuscle actin (α-SM-actin), the marker of phenotypic differentiation from fibroblasts to myofibroblasts, were determined using real-time quantitative RT-PCR (real-time RT-PCR) and Western blotting, respectively.
  
  
  RESULTS
  UII stimulated the secretion of TGF-β1 in cultured adventitial fibroblasts in a time-dependent manner. The secretion reached a peak at 24 hours, was higher by 69.8% (P < 0.01), than the control group. This effect was also concentration dependent. Maximal stimulation was reached at 10(-8) mol/L of UII (P < 0.01), which was increased by 59.9%, compared with in the control group (P < 0.01). The secretion of TGF-β1 induced by UII was significantly blocked by SB-710411 (10(-7) mol/L), a specific antagonist of UII receptor. In addition, both UII (10(-8) mol/L) and TGF-β1 significantly stimulated α-SM-actin mRNA and protein expression. Moreover, the α-SM-actin induced by UII was inhibited by the specific neutralizing antibody (20 µg/ml) of TGF-β1, while the α-SM-actin expression stimulated by TGF-β1 (20 ng/ml) was inhibited by SB-710411 (10(-7) mol/L), the UII receptor antagonist.
  
  
  CONCLUSIONS
  This study suggests that UII could induce TGF-β1 secretion in adventitial fibroblasts via UT activation, and TGF-β1 might be involved in phenotypic differentiation from adventitial fibroblasts into myofibroblasts induced by UII, and TGF-β1 signaling might be one of the important pathways by which UII is involved in vascular fibrosis.
authors.affiliation: Department of Cardiovascular Diseases, First Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, China. zhangyg8686@hotmail.com
authors.forename: Yong-Gang
authors.initials: YG
authors.lastname: Zhang
authors.forename: Yan-Chao
authors.initials: YC
authors.lastname: Hu
authors.forename: Yan-Yan
authors.initials: YY
authors.lastname: Mao
authors.forename: Rui-Hong
authors.initials: RH
authors.lastname: Wei
authors.forename: Shi-Lin
authors.initials: SL
authors.lastname: Bao
authors.forename: Li-Biao
authors.initials: LB
authors.lastname: Wu
authors.forename: Ze-Jian
authors.initials: ZJ
authors.lastname: Kuang
mesh_terms: D000199:Actins / Q000032:analysis / Q000235:genetics; D000818:Animals; D001011:Aorta / Q000166:cytology*; D054338:Cell Transdifferentiation / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects*; D008297:Male; D058628:Myofibroblasts / Q000166:cytology; D010641:Phenotype; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D053773:Transforming Growth Factor beta1 / Q000502:physiology*; D014579:Urotensins / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: D000199:Actins; D012333:RNA, Messenger; D053773:Transforming Growth Factor beta1; D014579:Urotensins; C498862:Acta2 protein, rat; C029677:urotensin II