The actin binding site on thymosin β4 promotes angiogenesis
The actin binding site on thymosin β4 promotes angiogenesis
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DOI：
10.1096/fj.03-0121fje
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发表时间：
2003-09-01
期刊：
影响因子：
4.8
通讯作者：
Kleinman, HK
中科院分区：
文献类型：
--
作者：
Philp, D;Huff, T;Kleinman, HK
胸腺素β（4）是普遍存在的43个氨基酸、5 kDa多肽，其是细胞增殖、迁移和分化的重要介质。它是哺乳动物组织中β-胸腺素家族中最丰富的成员，被认为是主要的G-肌动蛋白螯合肽。胸腺素β（4）是血管生成的，可以促进内皮细胞迁移和粘附，小管形成，主动脉环发芽和血管生成。当应用于皮肤伤口愈合测定时，它还加速伤口愈合并减少炎症。利用天然存在的胸腺素β（4）、蛋白水解片段和合成肽，我们发现胸腺素β（4）的一个7个氨基酸的肌动蛋白结合基序对其血管生成活性是必不可少的。用人脐静脉内皮细胞进行的迁移试验和用鸡主动脉弓进行的血管发芽试验表明，胸腺素β（4）和该肽的肌动蛋白结合基序在50 nM左右时显示出几乎相同的活性，而缺乏肌动蛋白基序的任何部分的肽都是无活性的。此外，与胸腺素β（4）的粘附被这七个氨基酸的肽阻断，证明它是分子上的主要胸腺素β（4）细胞结合位点。加入5-50 nM可溶性肌动蛋白可抑制胸腺素β（4）的粘附和发芽活性。这些结果表明，胸腺素β（4）的肌动蛋白结合基序是其血管生成活性的重要位点。
Thymosin beta(4) is a ubiquitous 43 amino acid, 5 kDa polypeptide that is an important mediator of cell proliferation, migration, and differentiation. It is the most abundant member of the beta-thymosin family in mammalian tissue and is regarded as the main G-actin sequestering peptide. Thymosin beta(4) is angiogenic and can promote endothelial cell migration and adhesion, tubule formation, aortic ring sprouting, and angiogenesis. It also accelerates wound healing and reduces inflammation when applied in dermal wound-healing assays. Using naturally occurring thymosin beta(4), proteolytic fragments, and synthetic peptides, we find that a seven amino acid actin binding motif of thymosin beta(4) is essential for its angiogenic activity. Migration assays with human umbilical vein endothelial cells and vessel sprouting assays using chick aortic arches show that thymosin beta(4) and the actin-binding motif of the peptide display near-identical activity at similar to50 nM, whereas peptides lacking any portion of the actin motif were inactive. Furthermore, adhesion to thymosin beta(4) was blocked by this seven amino acid peptide demonstrating it as the major thymosin beta(4) cell binding site on the molecule. The adhesion and sprouting activity of thymosin beta(4) was inhibited with the addition of 5-50 nM soluble actin. These results demonstrate that the actin binding motif of thymosin beta(4) is an essential site for its angiogenic activity.