Role of the low-affinity leukotriene B4 receptor BLT2 in VEGF-induced angiogenesis.
OBJECTIVE
The leukotriene B(4) (LTB(4)) receptor BLT2 is expressed in endothelium, but no clear physiological function for it has yet been identified, especially in vascular angiogenesis. The purpose of this study is to characterize the potential function of BLT2 in vascular endothelial growth factor (VEGF)-induced angiogenesis.


RESULTS
VEGF significantly upregulates BLT2 expression in human umbilical vein endothelial cells (HUVECs), and BLT2 knockdown by siRNA or inhibition of BLT2 by a specific BLT2 antagonist LY255283 attenuates VEGF-induced angiogenesis, which was determined by its effect on the formation of tube-like structures and on transmigration. The role of BLT2 in VEGF-induced angiogenesis was more evident in vivo, where BLT2 inhibition by LY255283 almost completely blocked VEGF-induced vessel formation in Matrigel-plug assays. In addition, we found that VEGF upregulates synthesis of the BLT2 ligand, 12(S)-hydroxyeicosatetraenoic acid (HETE). siRNA knockdown of 12-lipoxygenase (12-LO) expression attenuates VEGF-induced angiogenesis in HUVECs, and the addition of 12(S)-HETE to the 12-LO knockdown-HUVECs restores VEGF-induced angiogenesis. The activation of BLT2 itself by either 12(S)-HETE or LTB(4) evoked significant angiogenic phenotypes, both in vitro and in vivo.


CONCLUSIONS
Our findings indicate that BLT2 plays an essential role in mediating VEGF-induced angiogenesis.
Kim
Geun-Young
GY
College of Life Sciences and Biotechnology, Korea University, 5-1 Anam-dong, Sungbuk-gu, Seoul, 136-701, Korea.
Lee
Jin-Wook
JW
Cho
Sung-Hoon
SH
Seo
Ji-Min
JM
Kim
Jae-Hong
JH
D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000378:metabolism; D000818:Animals; D001092:Arachidonate 12-Lipoxygenase / Q000378:metabolism; D002465:Cell Movement; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D020024:Leukotriene Antagonists / Q000494:pharmacology; D007975:Leukotriene B4 / Q000378:metabolism; D008024:Ligands; D051379:Mice; D008822:Mice, Transgenic; D018919:Neovascularization, Physiologic / Q000187:drug effects; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D018102:Receptors, Leukotriene B4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D013777:Tetrazoles / Q000494:pharmacology; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
C513240:LTB4R protein, human; C485878:LTB4R2 protein, human; D020024:Leukotriene Antagonists; D008024:Ligands; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D018102:Receptors, Leukotriene B4; D013777:Tetrazoles; D042461:Vascular Endothelial Growth Factor A; D007975:Leukotriene B4; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D001092:Arachidonate 12-Lipoxygenase; C063823:LY 255283