Angiotensin AT(1) and AT(2) receptors differentially regulate angiopoietin-2 and vascular endothelial growth factor expression and angiogenesis by modulating heparin binding-epidermal growth factor (EGF)-mediated EGF receptor transactivation.
Angiotensin II (Ang II)-mediated signals are transmitted via heparin binding epidermal growth factor (EGF)-like growth factor (HB-EGF) release followed by transactivation of EGF receptor (EGFR). Although Ang II and HB-EGF induce angiogenesis, their link to the angiopoietin (Ang)-Tie2 system remains undefined. We tested the effects of Ang II on Ang1, Ang2, or Tie2 expression in cardiac microvascular endothelial cells expressing the Ang II receptors AT(1) and AT(2). Ang II significantly induced Ang2 mRNA accumulations without affecting Ang1 or Tie2 expression, which was inhibited by protein kinase C inhibitors and by intracellular Ca(2+) chelating agents. Ang II transactivated EGFR via AT(1), and inhibition of EGFR abolished the induction of Ang2. Ang II caused processing of pro-HB-EGF in a metalloproteinase-dependent manner to stimulate maturation and release of HB-EGF. Neutralizing anti-HB-EGF antibody blocked EGFR phosphorylation by Ang II. Ang II also upregulated vascular endothelial growth factor (VEGF) expression in an HB-EGF/EGFR-dependent manner. AT(2) inhibited AT(1)-mediated Ang2 expression and phosphorylation of EGFR. In an in vivo corneal assay, AT(1) induced angiogenesis in an HB-EGF-dependent manner and enhanced the angiogenic activity of VEGF. Although neither Ang2 nor Ang1 alone induced angiogenesis, soluble Tie2-Fc that binds to angiopoietins attenuated AT(1)-mediated angiogenesis. These findings suggested that (1) Ang II induces Ang2 and VEGF expression without affecting Ang1 or Tie2 and (2) AT(1) stimulates processing of pro-HB-EGF by metalloproteinases, and the released HB-EGF transactivates EGFR to induce angiogenesis via the combined effect of Ang2 and VEGF, whereas AT(2) attenuates them by blocking EGFR phosphorylation. Thus, Ang II is involved in the VEGF-Ang-Tie2 system via HB-EGF-mediated EGFR transactivation, and this link should be considerable in pathological conditions in which collateral blood flow is required.
Fujiyama
S
S
Department of Medicine II, Kansai Medical University, Osaka, Japan.
Matsubara
H
H
Nozawa
Y
Y
Maruyama
K
K
Mori
Y
Y
Tsutsumi
Y
Y
Masaki
H
H
Uchiyama
Y
Y
Koyama
Y
Y
Nose
A
A
Iba
O
O
Tateishi
E
E
Ogata
N
N
Jyo
N
N
Higashiyama
S
S
Iwasaka
T
T
D042683:Angiopoietin-1; D042702:Angiopoietin-2; D000804:Angiotensin II / Q000494:pharmacology; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003315:Cornea / Q000098:blood supply / Q000187:drug effects; D016228:Endothelial Growth Factors / Q000235:genetics*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000502:physiology*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D066257:Heparin-binding EGF-like Growth Factor; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines / Q000235:genetics*; D008301:Maleimides / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000235:genetics; D009281:Naphthalenes / Q000494:pharmacology; D018919:Neovascularization, Physiologic / Q000187:drug effects / Q000502:physiology*; D000068557:Olmesartan Medoxomil; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011506:Proteins / Q000235:genetics*; D011725:Pyridines / Q000494:pharmacology; D011799:Quinazolines; D020871:RNA Stability / Q000187:drug effects; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D042787:Receptor, TIE-2; D011945:Receptors, Angiotensin / Q000502:physiology*; D011956:Receptors, Cell Surface; D042764:Receptors, TIE; D013777:Tetrazoles / Q000494:pharmacology; D013997:Time Factors; D015533:Transcriptional Activation; D020032:Tyrphostins / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D042683:Angiopoietin-1; D042702:Angiopoietin-2; D057911:Angiotensin Receptor Antagonists; C467629:Angpt1 protein, rat; D016228:Endothelial Growth Factors; C587885:Hbegf protein, rat; D066257:Heparin-binding EGF-like Growth Factor; D007093:Imidazoles; D007211:Indoles; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D008301:Maleimides; D008562:Membrane Glycoproteins; D009281:Naphthalenes; D011506:Proteins; D011725:Pyridines; D011799:Quinazolines; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin; D011956:Receptors, Cell Surface; D013777:Tetrazoles; D020032:Tyrphostins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000804:Angiotensin II; C073402:PD 123319; C101044:RTKI cpd; D004815:Epidermal Growth Factor; D000068557:Olmesartan Medoxomil; D066246:ErbB Receptors; D020794:Receptor Protein-Tyrosine Kinases; D042787:Receptor, TIE-2; D042764:Receptors, TIE; D011493:Protein Kinase C; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; C058819:calphostin C; C070515:bisindolylmaleimide I; D002118:Calcium