Interleukin-1 beta upregulates cardiac expression of vascular endothelial growth factor and its receptor KDR/flk-1 via activation of protein tyrosine kinases.
Vascular endothelial growth factor (VEGF) is not only an endothelial cell-specific angiogenic factor but also a potent mediator of vascular permeability. Interleukin-1 beta (IL-1 beta) is a pro-inflammatory cytokine that has numerous effects on the pathogenesis of the tissue injury. To explore the possible regulation of the VEGF system by IL-1 beta in the heart, we examined the regulation of expression of VEGF and KDR/flk-1 (one of the VEGF receptors) by IL-1 beta using cardiac myocytes and cardiac microvascular endothelial cells (CMEC). Both cardiac myocytes and CMEC substantially expressed VEGF mRNA and its expression was increased 3.6- and 2.4-fold by IL-1 beta, respectively. IL-1 beta-induced accumulations of VEGF mRNA in cardiac myocytes were abolished by the tyrosine kinase inhibitor genistein, whereas inhibition of protein kinase C (PKC) by staurosporin, calphostin C and phorbol ester-induced PKC depletion, and intracellular Ca2+ chelators did not affect the induction of VEGF mRNA by IL-1 beta. Relatively smaller amounts of KDR/flk-1 mRNA were detected in CMEC, but not in cardiac myocytes, and the analysis using quantitative reverse transcription-polymerase chain reaction revealed that IL-1 beta significantly stimulated the accumulation of KDR/flk-1 mRNA 3.0-fold. VEGF protein (23 kDa) levels in Western blot analysis were increased 4.2- and 3.4-fold by IL-1 beta in cardiac myocytes and CMEC, respectively. KDR/flk-1 protein (230 kDa) levels in CMEC were also increased 3.2-fold by IL-1 beta. In addition, pre-treatment of CMEC by IL-1 beta markedly enhanced VEGF-induced tyrosine phosphorylation of focal adhesion kinase compared with that in the unstimulated cells. These findings indicate that cardiac VEGF-KDR/flk-1 system is upregulated by IL-1 beta via activation of tyrosine kinases, suggesting that the IL-1 beta-modulated autocrine and/or paracrine system of VEGF has an important role in the process of angiogenesis in ischemic hearts.
Maruyama
K
K
Department of Medicine II, Kansai Medical University, Osaka, Japan.
Mori
Y
Y
Murasawa
S
S
Masaki
H
H
Takahashi
N
N
Tsutusmi
Y
Y
Moriguchi
Y
Y
Shibazaki
Y
Y
Tanaka
Y
Y
Shibuya
M
M
Inada
M
M
Matsubara
H
H
Iwasaka
T
T
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D016228:Endothelial Growth Factors / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019833:Genistein / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology*; D008222:Lymphokines / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000378:metabolism*; D040262:Receptors, Vascular Endothelial Growth Factor; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012260:Ribonucleases / Q000378:metabolism; D015290:Second Messenger Systems; D013997:Time Factors; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D015815:Cell Adhesion Molecules; D016228:Endothelial Growth Factors; D004791:Enzyme Inhibitors; D007375:Interleukin-1; D008222:Lymphokines; D017978:Receptors, Growth Factor; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; D012260:Ribonucleases