title: Protein z exerts pro-angiogenic effects and upregulates CXCR4.
abstract: OBJECTIVE
  Protein Z (PZ) is a vitamin K-dependent coagulation factor without catalytic activity. Evidence points towards PZ as an independent risk factor for the occurrence of human peripheral arterial disease. However, the role of PZ in ischemia-driven angiogenesis and vascular healing processes has not been elucidated so far.
  
  
  METHODS
  Angiogenic potency of PZ was assessed in established in vitro assays using endothelial cells. PZ-deficient (PZ(-/-)) mice and their wild-type littermates (PZ(+/+)) were subjected to hindlimb ischemia. Furthermore, PZ(-/-) mice were exposed to PZ expressing adenovirus (AdV-PZ) or control adenovirus (AdV-GFP). In an additional set of animals, PZ(-/-) mice were exposed to AdV-PZ and AdV-GFP, each in combination with the CXCR4 antagonist AMD3100.
  
  
  RESULTS
  In vitro, PZ stimulated migratory activity and capillary-like tube formation of endothelial cells comparable to SDF-1. PZ(-/-) mice exhibited diminished hypoxia-driven neovascularization and reperfusion in post-ischemic hindlimbs, which was restored by adenoviral gene transfer up to levels seen in PZ(+/+) mice. The stimulatory impact of PZ on endothelial cells in vitro was abolished by siRNA targeting against PZ and PZ was not able to restore reduced migration after knock-down of CXCR4. The increased surface expression of CXCR4 on PZ-stimulated endothelial cells and the abrogated restoration of PZ(-/-) mice via AdV-PZ after concomitant treatment with the CXCR4 antagonist AMD3100 supports the idea that PZ mediates angiogenesis via a G-protein coupled pathway and involves the SDF-1/CXCR4 axis. This is underlined by the fact that addition of the G-protein inhibitor PTX to PZ-stimulated endothelial cells abolished the effect of PZ on capillary-like tube formation.
  
  
  CONCLUSIONS
  The results of the current study reveal a role of PZ in ischemia-induced angiogenesis, which involves a G-protein coupled pathway and a raised surface expression of CXCR4. Our findings thereby extend the involvement of PZ from the coagulation cascade to a beneficial modulation of vascular homeostasis.
authors.affiliation: Institute for Experimental Surgery, University Hospital Rostock, Rostock, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Butschkau
authors.affiliation: Clinic for Anesthesiology and Critical Care Medicine, University Hospital Rostock, Rostock, Germany.
authors.forename: Nana-Maria
authors.initials: NM
authors.lastname: Wagner
authors.affiliation: Institute for Experimental Surgery, University Hospital Rostock, Rostock, Germany.
authors.forename: Berit
authors.initials: B
authors.lastname: Genz
authors.affiliation: Institute for Experimental Surgery, University Hospital Rostock, Rostock, Germany.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Vollmar
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001596:Benzylamines; D001798:Blood Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects; D054377:Chemokine CXCL12 / Q000378:metabolism; D000080027:Cyclams; D004195:Disease Models, Animal; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism; D006571:Heterocyclic Compounds / Q000494:pharmacology; D006614:Hindlimb; D061307:Human Umbilical Vein Endothelial Cells; D007511:Ischemia / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic / Q000187:drug effects; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D001596:Benzylamines; D001798:Blood Proteins; D054377:Chemokine CXCL12; C515256:Cxcl12 protein, mouse; D000080027:Cyclams; D006571:Heterocyclic Compounds; D034741:RNA, Small Interfering; D019718:Receptors, CXCR4; C026080:plasma protein Z; C088327:plerixafor