Faculty of Pharmacy, Laboratory of Pharmacology, Osaka Ohtani University, 3-11-1 Nishikiori-Kita, Tonda-bayashi, Osaka, Japan.
Glia. 2012 Dec;60(12):1954-63. doi: 10.1002/glia.22411. Epub 2012 Aug 23.
Vascular endothelial growth factors (VEGFs) and angiopoietins (ANGs) are involved in pathophysiological responses in damaged nerve tissues. Astrocytes produce VEGFs and ANGs upon brain ischemia and traumatic injury. To clarify the extracellular signals regulating VEGF and ANG production, effects of endothelins (ETs), a family of endothelium-derived peptides, were examined in cultured rat astrocytes. ET-1 (100 nM) and Ala(1,3,11,15)-ET-1 (100 nM), an ET(B) receptor agonist, increased VEGF-A mRNA levels in cultured astrocytes, while ANG-1 mRNA was decreased by ETs. ET-1 did not affect astrocytic VEGF-B, placental growth factor (PLGF), and ANG-2 mRNA levels. The effects of ET-1 on VEGF-A and ANG-1 mRNAs were inhibited by BQ788, an ET(B) antagonist. Release of VEGF-A proteins from cultured astrocytes was increased by ET-1. In contrast, ET-1 reduced release of astrocytic ANG-1. Exogenous ET-1 (100 nM) and VEGF(165) (100 ng/mL), an isopeptide of VEGF-A, stimulated bromodeoxyuridine (BrdU) incorporation into cultured astrocytes. Treatment with ET-1 and VEGF(165) increased the numbers of cyclin D1-positive astrocytes. Exogenous ANG-1 (250 ng/mL) did not stimulate the BrdU incorporation. Increases in BrdU incorporation by ET-1 and VEGF(165) were not affected by ANG-1. In 60-70% confluent cultures, SU4312 (10 μM), a VEGF receptor tyrosine kinase inhibitor, partially reduced the effects of ET-1 on BrdU incorporation and cyclin D1 expression. ET-induced BrdU incorporation and cyclin D1 expression were reduced by a neutralizing antibody against VEGF-A. Our findings suggest that ET-1 is a factor regulating astrocytic VEGF-A and ANG-1, and that increased VEGF-A production potentiates ET-induced astrocytic proliferation by an autocrine mechanism.
血管内皮生长因子（VEGFs）和血管生成素（ANGs）参与受损神经组织的病理生理反应。星形胶质细胞在脑缺血和创伤性损伤时产生 VEGFs 和 ANGs。为了阐明调节 VEGF 和 ANG 产生的细胞外信号，研究了内皮素（ETs）家族的内皮衍生肽对培养的大鼠星形胶质细胞的影响。ET-1（100 nM）和 Ala（1,3,11,15）-ET-1（100 nM），一种 ET（B）受体激动剂，增加了培养的星形胶质细胞中 VEGF-A mRNA 的水平，而 ETs 降低了 ANG-1 mRNA 的水平。ET-1 不影响星形胶质细胞的 VEGF-B、胎盘生长因子（PLGF）和 ANG-2 mRNA 水平。BQ788，一种 ET（B）拮抗剂，抑制了 ET-1 对 VEGF-A 和 ANG-1 mRNA 的作用。ET-1 增加了培养的星形胶质细胞中 VEGF-A 蛋白的释放。相反，ET-1 减少了星形胶质细胞 ANG-1 的释放。外源性 ET-1（100 nM）和 VEGF（165）（100 ng/mL），VEGF-A 的异肽，刺激了培养的星形胶质细胞中溴脱氧尿苷（BrdU）的掺入。用 ET-1 和 VEGF（165）处理增加了 cyclin D1 阳性星形胶质细胞的数量。外源性 ANG-1（250 ng/mL）不能刺激 BrdU 掺入。ET-1 和 VEGF（165）引起的 BrdU 掺入增加不受 ANG-1 的影响。在 60-70%汇合培养物中，VEGF 受体酪氨酸激酶抑制剂 SU4312（10 μM）部分降低了 ET-1 对 BrdU 掺入和 cyclin D1 表达的影响。ET 诱导的 BrdU 掺入和 cyclin D1 表达减少了针对 VEGF-A 的中和抗体。我们的发现表明，ET-1 是调节星形胶质细胞 VEGF-A 和 ANG-1 的因素，而增加的 VEGF-A 产生通过自分泌机制增强了 ET 诱导的星形胶质细胞增殖。
