Maruyama K, Mori Y, Murasawa S, Masaki H, Takahashi N, Tsutusmi Y, Moriguchi Y, Shibazaki Y, Tanaka Y, Shibuya M, Inada M, Matsubara H, Iwasaka T
Department of Medicine II, Kansai Medical University, Osaka, Japan.
J Mol Cell Cardiol. 1999 Mar;31(3):607-17. doi: 10.1006/jmcc.1998.0895.
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.
血管内皮生长因子（VEGF）不仅是一种内皮细胞特异性血管生成因子，也是血管通透性的强效介质。白细胞介素-1β（IL-1β）是一种促炎细胞因子，对组织损伤的发病机制有多种影响。为了探讨IL-1β在心脏中对VEGF系统的可能调节作用，我们使用心肌细胞和心脏微血管内皮细胞（CMEC）研究了IL-1β对VEGF和KDR/flk-1（VEGF受体之一）表达的调节。心肌细胞和CMEC均大量表达VEGF mRNA，其表达分别被IL-1β增加了3.6倍和2.4倍。酪氨酸激酶抑制剂金雀异黄素消除了IL-1β诱导的心肌细胞中VEGF mRNA的积累，而星形孢菌素、钙泊三醇对蛋白激酶C（PKC）的抑制、佛波酯诱导的PKC耗竭以及细胞内Ca2+螯合剂均不影响IL-1β对VEGF mRNA的诱导。在CMEC中检测到相对少量的KDR/flk-1 mRNA，但在心肌细胞中未检测到，定量逆转录-聚合酶链反应分析表明，IL-1β显著刺激KDR/flk-1 mRNA积累3.0倍。蛋白质印迹分析中，IL-1β使心肌细胞和CMEC中的VEGF蛋白（23 kDa）水平分别增加了4.2倍和3.4倍。IL-1β也使CMEC中的KDR/flk-1蛋白（230 kDa）水平增加了3.2倍。此外，与未刺激的细胞相比，IL-1β预处理CMEC显著增强了VEGF诱导的粘着斑激酶酪氨酸磷酸化。这些发现表明，心脏VEGF-KDR/flk-1系统通过酪氨酸激酶的激活被IL-1β上调，提示IL-1β调节的VEGF自分泌和/或旁分泌系统在缺血性心脏血管生成过程中起重要作用。
