title: 12/15-Lipoxygenase gene knockout severely impairs ischemia-induced angiogenesis due to lack of Rac1 farnesylation.
abstract: To understand the mechanisms by which 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE) activates Rac1 in the induction of angiogenesis, we studied the role of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase and αPix. 15(S)-HETE stimulated Rac1 in a sustained manner in human dermal microvascular endothelial cells (HDMVECs). Simvastatin, a potent inhibitor of HMG-CoA reductase, suppressed 15(S)-HETE-induced Rac1 activation in HDMVECs affecting their migration and tube formation. 15(S)-HETE by inducing HMG-CoA reductase expression caused increased farnesylation and membrane translocation of Rac1 where it became activated by Src-dependent αPix stimulation. Mevalonate rescued 15(S)-HETE-induced Rac1 farnesylation and membrane translocation in HDMVECs and the migration and tube formation of these cells from inhibition by simvastatin. Down-regulation of αPix inhibited 15(S)-HETE-induced HDMVEC migration and tube formation. Hind-limb ischemia induced Rac1 farnesylation and activation leading to increased angiogenesis and these effects were blocked by simvastatin and rescued by mevalonate in WT mice. In contrast, hind-limb ischemia failed to induce Rac1 farnesylation and activation as well as angiogenic response in 12/15-Lox(-/-) mice. Activation of Src and αPix were also compromised at least to some extent in 12/15-Lox(-/-) mice compared with WT mice in response to hind-limb ischemia. Together, these findings demonstrate for the first time that HMG-CoA reductase plays a determinant role in 12/15-Lox-induced angiogenesis.
authors.affiliation: Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
authors.forename: Nikhlesh K
authors.initials: NK
authors.lastname: Singh
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Kundumani-Sridharan
authors.forename: Gadiparthi N
authors.initials: GN
authors.lastname: Rao
mesh_terms: D000214:Acyl Coenzyme A; D000818:Animals; D001092:Arachidonate 12-Lipoxygenase / Q000235:genetics* / Q000378:metabolism*; D001093:Arachidonate 15-Lipoxygenase / Q000235:genetics* / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006614:Hindlimb / Q000098:blood supply; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000037:antagonists & inhibitors / Q000378:metabolism; D006903:Hydroxymethylglutaryl CoA Reductases / Q000235:genetics / Q000378:metabolism; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D007511:Ischemia / Q000235:genetics* / Q000503:physiopathology*; D008798:Mevalonic Acid / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic / Q000235:genetics*; D009479:Neuropeptides / Q000378:metabolism*; D054876:Prenylation / Q000187:drug effects / Q000502:physiology; D064067:Rho Guanine Nucleotide Exchange Factors; D019821:Simvastatin / Q000494:pharmacology; D020744:rac GTP-Binding Proteins / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein
chemical_list: C475064:12-15-lipoxygenase; D000214:Acyl Coenzyme A; D020662:Guanine Nucleotide Exchange Factors; D006893:Hydroxyeicosatetraenoic Acids; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D009479:Neuropeptides; C484602:Rac1 protein, mouse; D064067:Rho Guanine Nucleotide Exchange Factors; C008047:3-hydroxy-3-methylglutaryl-coenzyme A; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D019821:Simvastatin; D006903:Hydroxymethylglutaryl CoA Reductases; D001092:Arachidonate 12-Lipoxygenase; D001093:Arachidonate 15-Lipoxygenase; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D008798:Mevalonic Acid