title: Over-expression of neurotrophin 3 in human aortic valves affected by calcific disease induces the osteogenic responses via the Trk-Akt pathway.
abstract: Calcific aortic valve disease (CAVD) is a leading cardiovascular disorder in the elderly. While aortic valve interstitial cells (AVICs) are the main cells that express osteogenic mediators, the molecular mechanism that mediates AVIC osteogenic responses is incompletely understood. This study aims to identify pro-osteogenic factors in human AVICs affected by CAVD.
  
  
  RESULTS
  Microarray analysis identified 11 up-regulated genes in AVICs of diseased valves. Among these genes, mRNA levels of neurotrophin 3 (NT3) increased by 2 fold. Higher levels of NT3 protein in diseased aortic valves and diseased AVICs were confirmed by immunofluorescent staining and immunoblotting, respectively. An exposure of AVICs of normal valves to recombinant human NT3 (0.025-0.10μg/mL) up-regulated the production of Runx2, TGF-β1 and BMP-2 in a dose-dependent fashion. NT3 also promotes calcium deposit formation. The pro-osteogenic effect of NT3 was not affected by neutralization of Toll-like receptor 2 or 4. Interestingly, mRNA encoding neural growth factor receptors (TrkA, TrkB, TrkC and p75 NTR) was detectable in human AVICs. Inhibition of Trk receptors markedly reduced the effects of NT3 on Runx2, TGF-β1 and BMP-2 production, calcium deposit formation and Akt phosphorylation. Further, inhibition of Akt also reduced the pro-osteogenic effects of NT3.
  
  
  CONCLUSIONS
  AVICs of diseased human aortic valves express higher levels of NT3. NT3 up-regulates the production of Runx2, TGF-β1 and BMP-2, and promotes calcium deposit formation in human AVICs via the Trk-Akt pathway. Thus, NT3 is a novel pro-osteogenic factor in aortic valves and may play a role in valvular calcification.
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, CO 80045, United States; Medical Research Center of Guangdong General Hospital, Guangdong Academy of Medical Sciences, Southern Medical University, Guangzhou 510080, China.
authors.forename: Qingzhou
authors.initials: Q
authors.lastname: Yao
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, CO 80045, United States; Departments of Pathophysiology, Southern Medical University, Guangzhou 510515, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Song
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, CO 80045, United States.
authors.forename: Lihua
authors.initials: L
authors.lastname: Ao
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, CO 80045, United States; Departments of Cardiology of Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Zhan
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, CO 80045, United States.
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Cleveland
authors.affiliation: Medical Research Center of Guangdong General Hospital, Guangdong Academy of Medical Sciences, Southern Medical University, Guangzhou 510080, China. Electronic address: yuxycn@aliyun.com.
authors.forename: Xiyong
authors.initials: X
authors.lastname: Yu
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, CO 80045, United States.
authors.forename: David A
authors.initials: DA
authors.lastname: Fullerton
authors.affiliation: Department of Surgery, University of Colorado Denver, Aurora, CO 80045, United States. Electronic address: Xianzhong.meng@ucdenver.edu.
authors.forename: Xianzhong
authors.initials: X
authors.lastname: Meng
keywords: Akt; Aortic valve; Neurotrophin 3; Pro-osteogenic mediators; Trk