Doi K, Itoh H, Nakagawa O, Igaki T, Yamashita J, Chun T H, Inoue M, Masatsugu K, Nakao K
Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, Japan.
Heart Vessels. 1997;Suppl 12:18-22.
The natriuretic peptide family consists of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). We have elucidated that CNP is synthesized by endothelial cells. We have also shown that CNP secretion is potently suppressed by vascular endothelial growth factor (VEGF). In the present study, we examined the developmental gene expression of the natriuretic peptide system with the expression of VEGF and endothelial cell-specific receptor tyrosine kinases (RTKs), which expression is necessary for vasculogenesis, using embryoid bodies (EB) as an in vitro model for vascular development. When mouse embryonic stem (ES) cells were cultured in suspension culture, ES cells spontaneously differentiated into EB on day 4 and then into cystic EB (day 10). The VEGF gene transcript was detected early, on day 4. The expression of Flk-1, and flt-1 (the two VEGF receptors) and also of tie-2, which is crucial for blood island formation, was detected as early as day 4, and also on days 8 and 21. In contrast, the expression of flt-4, the receptor for VEGF-C, and tie-1, was first detected on day 21. Along with the developmental expression of these markers of differentiation for endothelial cells, the gene expression of CNP and its specific receptor, ANP-B receptor, was detected on days 4, 8, and 21. In contrast, the gene expression of BNP, which acts as a cardiac hormone, and the gene expression of the ANP-A receptor, which is specific to ANP and BNP, was first detected on days 8 and 21, respectively. These results indicate the distinct role of CNP in the natriuretic peptide family and the close linkage of CNP expression and endothelial cell differentiation, suggesting a possible role of CNP in vasculogenesis.
利钠肽家族由心房利钠肽（ANP）、脑利钠肽（BNP）和C型利钠肽（CNP）组成。我们已经阐明CNP是由内皮细胞合成的。我们还表明，血管内皮生长因子（VEGF）能有效抑制CNP的分泌。在本研究中，我们以胚状体（EB）作为血管发育的体外模型，研究了利钠肽系统的发育基因表达以及VEGF和内皮细胞特异性受体酪氨酸激酶（RTK）的表达，后者的表达对于血管生成是必需的。当小鼠胚胎干细胞（ES细胞）在悬浮培养中培养时，ES细胞在第4天自发分化为EB，然后在第10天分化为囊性EB。VEGF基因转录本在第4天早期就被检测到。Flk-1和flt-1（两种VEGF受体）以及对血岛形成至关重要的tie-2的表达最早在第4天被检测到，在第8天和第21天也被检测到。相比之下，VEGF-C受体flt-4和tie-1的表达最早在第21天被检测到。随着这些内皮细胞分化标志物的发育表达，CNP及其特异性受体ANP-B受体的基因表达在第4天、第8天和第21天被检测到。相比之下，作为心脏激素的BNP的基因表达以及ANP和BNP特异性的ANP-A受体的基因表达分别最早在第8天和第21天被检测到。这些结果表明CNP在利钠肽家族中的独特作用以及CNP表达与内皮细胞分化的紧密联系，提示CNP在血管生成中可能发挥作用。
