Semaphorin-3A and semaphorin-3F work together to repel endothelial cells and to inhibit their survival by induction of apoptosis
Semaphorin-3A and semaphorin-3F work together to repel endothelial cells and to inhibit their survival by induction of apoptosis
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DOI：
10.1074/jbc.m609711200
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发表时间：
2007-09-07
影响因子：
4.8
通讯作者：
Neufeld, Gera
中科院分区：
文献类型：
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作者：
Guttmann-Raviv, Noga;Shraga-Heled, Niva;Neufeld, Gera
信号素- 3a （sema3A）是一种神经匹林-1 （np1）激动剂。它抑制165个氨基酸形式的VEGF（VEGF(165)）与np1的结合，并因此抑制血管生成。然而，我们发现抑制VEGF（165）的有丝分裂作用的sema3A浓度不会抑制VEGF（165）诱导的VEGF受体-2 （VEGFR-2）的磷酸化。此外，sema3A抑制VEGF的生物学效应（121），VEGF是一种不与神经磷脂和碱性成纤维细胞生长因子结合的VEGF形式，与VEGF不同，碱性成纤维细胞生长因子的活性不受针对np1的小干扰RNA的抑制。因此，sema3A抑制VEGF165活性的机制并不依赖于与VEGF165结合np1的竞争。Sema3A诱导人脐静脉源性内皮细胞的局灶性接触迅速消失，随后肌动蛋白细胞骨架崩溃。表达sema3A的HEK293细胞排斥人内皮细胞，高浓度诱导内皮细胞凋亡死亡。此外，在体外血管生成实验中，sema3A抑制内皮细胞形成管。神经肽-2 （np2）激动剂sema3F也有类似的作用。这些抑制作用被分别针对np1或np2的小干扰rna所消除。当信号素作为纯蛋白加入时，sema3A和sema3F的抗增殖作用是叠加的。然而，当sema3A和sema3F在HEK293细胞中共表达时，它们的促凋亡和细胞排斥活性似乎是协同的。这些观察结果表明，sema3A和sema3F的组合可能比单个信号蛋白更有效地抑制肿瘤血管生成。
Semaphorin-3A (sema3A) is a neuropilin-1 (np1) agonist. It inhibits the binding of the 165-amino acid form of VEGF (VEGF(165)) to np1 and was reported to inhibit angiogenesis as a result. However, we find that sema3A concentrations that inhibit the mitogenic effects of VEGF(165) do not inhibit VEGF(165) induced phosphorylation of VEGF receptor-2 (VEGFR-2). Furthermore, sema3A inhibits the biological effects of VEGF(121), a VEGF form that does not bind to neuropilins and basic fibroblast growth factor, a growth factor whose activity, unlike that of VEGF, is not inhibited by small interfering RNA directed against np1. Therefore, the mechanism by which sema3A inhibits VEGF165 activity does not depend on competition with VEGF165 for binding to np1. Sema3A induced rapid disappearance of focal contacts followed by collapse of the actin cytoskeleton in human umbilical vein-derived endothelial cells. HEK293 cells expressing sema3A repel human endothelial cells and at high concentrations induce their death by apoptosis. Furthermore, sema3A inhibited the formation of tubes from endothelial cells in an in vitro angiogenesis assay. Similar effects are induced by the neuropilin-2 (np2) agonist sema3F. These inhibitory effects are abrogated by small interfering RNAs directed against np1 or np2, respectively. The anti-proliferative effects of sema3A and sema3F are additive when the semaphorins are added as pure proteins. However, when sema3A and sema3F were co-expressed in HEK293 cells their pro-apoptotic and cell repellant activities appeared to be synergistic. These observations suggest that combinations of sema3A and sema3F may be able to inhibit tumor angiogenesis more effectively than single semaphorins.