Peroxisome proliferator-activated receptor alpha is crucial for iloprost-induced in vivo angiogenesis and vascular endothelial growth factor upregulation.
We have previously demonstrated that iloprost, a stable prostacyclin (PGI(2)) analogue, induces angiogenesis in vivo, through a vascular endothelial growth factor (VEGF)-dependent mechanism. In this study, we demonstrate that iloprost-induced angiogenesis and VEGF upregulation are modulated by peroxisome proliferator-activated receptor-alpha (PPARalpha), a ligand-inducible transcription factor that belongs to the nuclear hormone receptor superfamily and plays multiple biological activities in the vascular system. We show that iloprost is unable to induce angiogenesis in mice lacking the PPARalpha gene (PPARalpha-/- mice). Likewise, iloprost-induced VEGF upregulation is absent in PPARalpha-/- mice. In contrast, iloprost induces a robust angiogenic response in wild-type mice, along with local upregulation of VEGF. Importantly, mice lacking the PPARalpha gene exhibit a normal angiogenic response to VEGF, indicating that the absence of PPARalpha does not result in a general impairment of angiogenesis, but specifically affects the ability of iloprost to induce angiogenesis. Our data demonstrate unexpected functional relationships between the PGI(2) system and the PPAR signaling pathway and shed new light on the molecular mechanisms involved in iloprost-induced angiogenesis.
Biscetti
Federico
F
Laboratory of Vascular Biology and Genetics, Department of Medicine, A. Gemelli University Hospital, Rome, Italy.
Gaetani
Eleonora
E
Flex
Andrea
A
Straface
Giuseppe
G
Pecorini
Giovanni
G
Angelini
Flavia
F
Stigliano
Egidio
E
Aprahamian
Tamar
T
Smith
Roy C
RC
Castellot
John J
JJ
Pola
Roberto
R
D043925:Angiogenesis Inducing Agents / Q000494:pharmacology* / Q000633:toxicity; D000818:Animals; D016510:Corneal Neovascularization / Q000139:chemically induced* / Q000378:metabolism; D016285:Iloprost / Q000494:pharmacology* / Q000633:toxicity; D051379:Mice; D018345:Mice, Knockout; D047493:PPAR alpha / Q000172:deficiency / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000235:genetics / Q000378:metabolism
D043925:Angiogenesis Inducing Agents; D047493:PPAR alpha; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; C501163:Flt1 protein, mouse; D040281:Vascular Endothelial Growth Factor Receptor-1; D016285:Iloprost