Extracellular regulation of VEGF: Isoforms, proteolysis, and vascular patterning

Prakash Vempati, Aleksander S. Popel, Feilim Mac Gabhann

Research output: Contribution to journalReview articlepeer-review

Abstract

The regulation of vascular endothelial growth factor A (VEGF) is critical to neovascularization in numerous tissues under physiological and pathological conditions. VEGF has multiple isoforms, created by alternative splicing or proteolytic cleavage, and characterized by different receptor-binding and matrix-binding properties. These isoforms are known to give rise to a spectrum of angiogenesis patterns marked by differences in branching, which has functional implications for tissues. In this review, we detail the extensive extracellular regulation of VEGF and the ability of VEGF to dictate the vascular phenotype. We explore the role of VEGF-releasing proteases and soluble carrier molecules on VEGF activity. While proteases such as MMP9 can 'release' matrix-bound VEGF and promote angiogenesis, for example as a key step in carcinogenesis, proteases can also suppress VEGF's angiogenic effects. We explore what dictates pro- or anti-angiogenic behavior. We also seek to understand the phenomenon of VEGF gradient formation. Strong VEGF gradients are thought to be due to decreased rates of diffusion from reversible matrix binding, however theoretical studies show that this scenario cannot give rise to lasting VEGF gradients in vivo. We propose that gradients are formed through degradation of sequestered VEGF. Finally, we review how different aspects of the VEGF signal, such as its concentration, gradient, matrix-binding, and NRP1-binding can differentially affect angiogenesis. We explore how this allows VEGF to regulate the formation of vascular networks across a spectrum of high to low branching densities, and from normal to pathological angiogenesis. A better understanding of the control of angiogenesis is necessary to improve upon limitations of current angiogenic therapies.

Original languageEnglish (US)
Pages (from-to)1-19
Number of pages19
JournalCytokine and Growth Factor Reviews
Volume25
Issue number1
DOIs
StatePublished - Feb 2014

Keywords

  • Angiogenesis
  • Computational model
  • Extracellular matrix
  • Gradient
  • Mathematical model
  • Microenvironment
  • Protease
  • Receptor
  • Systems biology

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Immunology and Allergy
  • Immunology
  • Biochemistry, Genetics and Molecular Biology(all)

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