title: Lysophosphatidic acid suppresses endothelial cell CD36 expression and promotes angiogenesis via a PKD-1-dependent signaling pathway.
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.
authors: Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH 44195, USA.
authors: Bin
authors: B
authors: Ren
authors: James
authors: J
authors: Hale
authors: Sowmya
authors: S
authors: Srikanthan
authors: Roy L
authors: RL
authors: Silverstein
mesh_terms: D000818:Animals; D015153:Blotting, Western; D018955:CD36 Antigens / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D020405:Dermis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015536:Down-Regulation; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D047468:Immunoprecipitation; D008246:Lysophospholipids / Q000494:pharmacology*; D051379:Mice; D018919:Neovascularization, Physiologic; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D049368:Receptors, Lysophosphatidic Acid / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D050396:TRPP Cation Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019700:Thrombospondin 1 / Q000494:pharmacology; D014158:Transcription, Genetic
chemical_list: D018955:CD36 Antigens; D008246:Lysophospholipids; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D049368:Receptors, Lysophosphatidic Acid; D050396:TRPP Cation Channels; D019700:Thrombospondin 1; C032881:lysophosphatidic acid