title: Age-related Notch-4 quiescence is associated with altered wall remodeling during vein graft adaptation.
abstract: BACKGROUND
  The link of aging to specific mechanisms of vascular biology is not well understood. We have previously shown that aging is associated with increased vein graft wall thickness and that this process involves the VEGF-Delta/Notch-ephrin/Eph cascade. Therefore, we examined whether Dll-4 or Notch-4 are differentially expressed, according to age, during vein graft adaptation.
  
  
  METHODS
  Vein grafts were performed in 6-mo and 24-mo Fischer 344 rats. Gene expression was analyzed by quantitative real-time PCR, and the distribution of Dll-4 and Notch-4 was observed by immunofluorescence.
  
  
  RESULTS
  The expression of Dll-4 and Notch-4 was reduced in vein grafts performed in aged rats compared with the expression in young adult rats. Both Dll-4 and Notch-4 were distributed in vein graft endothelium as well as the outer adventitia, with reduced amounts in the outer adventitia of aged vein grafts. Aged veins had reduced eNOS membrane targeting and colocalization with caveolin-1 as well as reduced eNOS protein expression in comparison to young adult veins. In an exchange model between young and aged animals, heterogeneous vein grafts (Yo(Ag) and Ag(Yo)) showed significantly thicker neointima compared with young (Yo(Yo)) controls, and had Notch-4-positive cells, but not Dll-4-positive cells, diminished in the adventitia. Vein grafts that were air-denuded of endothelium did not show any adaptation to the arterial environment and also lacked both Dll-4 and Notch-4 expression at 3 wk.
  
  
  CONCLUSIONS
  During vein graft adaptation to the arterial environment, both Dll-4 and Notch-4 expression are down-regulated in an aged, but not a young, background. Loss of Notch-4 is associated with loss of attenuation of neointima. The delta-Notch signaling pathway may be active during vein graft adaptation.
authors.affiliation: Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut 06520-8089, USA.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Kondo
authors.forename: Akihito
authors.initials: A
authors.lastname: Muto
authors.forename: Fabio A
authors.initials: FA
authors.lastname: Kudo
authors.forename: Lynn
authors.initials: L
authors.lastname: Model
authors.forename: Sammy
authors.initials: S
authors.lastname: Eghbalieh
authors.forename: Paraag
authors.initials: P
authors.lastname: Chowdhary
authors.forename: Alan
authors.initials: A
authors.lastname: Dardik
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000375:Aging / Q000502:physiology*; D000818:Animals; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000502:physiology; D015870:Gene Expression / Q000502:physiology; D006085:Graft Survival / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D007601:Jugular Veins / Q000502:physiology / Q000601:surgery*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D058426:Neointima / Q000378:metabolism / Q000503:physiopathology; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D000074562:Receptor, Notch4; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D058017:Vascular Grafting / Q000379:methods*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C560417:Notch4 protein, rat; D000074562:Receptor, Notch4; D051880:Receptors, Notch; C064045:delta protein; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat