Blood Journal
Leading the way in experimental and clinical research in hematology

Lysophosphatidic acid suppresses endothelial cell CD36 expression and promotes angiogenesis via a PKD-1–dependent signaling pathway

  1. Bin Ren1,
  2. James Hale1,2,
  3. Sowmya Srikanthan1,3, and
  4. Roy L. Silverstein1,3
  1. 1Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH;
  2. 2Department of Biology, Geology and Environmental Science, Cleveland State University, Cleveland, OH; and
  3. 3Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH

Abstract

In pathologic settings including retinal ischemia and malignant tumors, robust angiogenesis occurs despite the presence in the microenvironment of antiangiogenic proteins containing thrombospondin structural homology (TSR) domains. We hypothesized that antiangiogenesis mediated by TSR-containing proteins could be blunted by localized down-regulation of their cognate receptor on microvascular endothelial cells (MVECs), CD36. Through screening a panel of endothelial cell agonists, we found that lysophosphatidic acid (LPA) dramatically down-regulated CD36 surface expression on primary MVECs. LPA is a lipid-signaling mediator known to have proangiogenic activity, but the mechanisms are largely unknown. We observed that LPA caused CD36 down-regulation in a dose- and time-dependent manner and was long lasting. Down-regulation occurred at the transcriptional level via a signaling pathway involving specific LPA receptors and protein kinase D. LPA-induced MVEC CD36 repression significantly attenuated in vitro antiangiogenic responses to thrombospondin-1, including blockade of migration, tube formation, and VEGFR-2 signaling in response to fibroblast growth factor-2. In vivo relevance was demonstrated by showing that LPA abrogated thrombospondin-1–mediated inhibition of neovascularization of Matrigel plugs implanted in mice. Our data thus indicate that the proangiogenic mechanism of LPA may in part be via switching off the antiangiogenic switch mediated by TSR proteins and CD36.

  • Submitted December 20, 2010.
  • Accepted March 15, 2011.
View Full Text