Protein z exerts pro-angiogenic effects and upregulates CXCR4

PLoS One. 2014 Dec 4;9(12):e113554. doi: 10.1371/journal.pone.0113554. eCollection 2014.

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.

Approach: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoviridae / genetics
  • Animals
  • Benzylamines
  • Blood Proteins / antagonists & inhibitors
  • Blood Proteins / genetics
  • Blood Proteins / metabolism*
  • Cell Movement / drug effects
  • Chemokine CXCL12 / metabolism
  • Cyclams
  • Disease Models, Animal
  • Genetic Vectors / genetics
  • Genetic Vectors / metabolism
  • Heterocyclic Compounds / pharmacology
  • Hindlimb
  • Human Umbilical Vein Endothelial Cells
  • Ischemia / metabolism
  • Ischemia / pathology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Neovascularization, Physiologic / drug effects
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Receptors, CXCR4 / antagonists & inhibitors
  • Receptors, CXCR4 / genetics
  • Receptors, CXCR4 / metabolism*
  • Up-Regulation / drug effects

Substances

  • Benzylamines
  • Blood Proteins
  • Chemokine CXCL12
  • Cxcl12 protein, mouse
  • Cyclams
  • Heterocyclic Compounds
  • RNA, Small Interfering
  • Receptors, CXCR4
  • plasma protein Z
  • plerixafor

Grant support

This work was supported by a grant of the Deutsche Forschungsgemeinschaft DFG (VO 450/11-1). BV received the funding. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.