TGF-β induces proangiogenic and antiangiogenic factors via parallel but distinct Smad pathways
TGF-β induces proangiogenic and antiangiogenic factors via parallel but distinct Smad pathways
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DOI：
10.1111/j.1523-1755.2004.00780.x
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发表时间：
2004-08-01
影响因子：
19.6
通讯作者：
Johnson, RJ
中科院分区：
文献类型：
--
作者：
Nakagawa, T;Li, JH;Johnson, RJ
背景血管生成在许多疾病过程中具有关键作用。血管内皮生长因子（VEGF-A）是最重要的血管生成因子之一，而血小板反应蛋白-1（TSP-1）是主要的抗血管生成因子。最近的研究表明，VEGF-A和TSP-1都受到转化生长因子β 1（TGF-β 1）的调节，但其机制尚不清楚。我们研究了TGF-β 1及其信号通路在介导这两种分子表达中的作用。用TGF-β 1刺激大鼠近端肾小管细胞（NRK 52 E）以诱导VEGF-A和TSP-1合成。为了阐明受体激活的Smads（R-Smads）的作用，我们使用抑制性Smad，Smad 7的过表达以及使用野生型或敲除小鼠的成纤维细胞来阻断Smad信号传导。为了确认Smads的抗抗原作用，还检查了响应于TGF-β 1的可溶性Flt-1调节。此外，还检测了NRK 52 E和Smad基因敲除细胞的条件培养基对内皮细胞增殖的影响。NRK 52 E细胞中TGF-β 1对VEGF-A和TSP-1的诱导与通路限制性R-Smads（Smad 2和3）的激活相关，通过过表达Smad 7阻断这些Smads可阻断其诱导。通过使用Smad敲除细胞，显示Smad 3在刺激VEGF-A表达中具有关键作用，而Smad 2对TSP-1表达至关重要。与Smad 2具有抗血管生成功能的假设一致，我们还证明了Smad 2，而不是Smad 3，介导了VEGF-A拮抗剂，可溶性VEGF-A受体sFlt-1的表达，对TGF-β 1的反应。NRK 52 E的条件培养基经TGF-β 1刺激24小时后，不诱导内皮细胞增殖。Smad 2基因敲除的条件培养基诱导内皮细胞增殖，而Smad 3基因敲除的条件培养基抑制内皮细胞增殖。R-Smads在介导促血管生成和抗血管生成生长因子对TGF-β 1的反应中具有不同的作用。
Background. Angiogenesis has a key role in numerous disease processes. One of the most important angiogenic factors is vascular endothelial growth factor (VEGF-A), whereas thrombospondin-1 (TSP-1) is a major antiangiogenic factor. Recent studies have shown that VEGF-A as well as TSP-1 is regulated by transforming growth factor-beta1 (TGF-beta1), but the mechanism remains unclear.Methods. We examined the role of TGF-beta1 and its signaling pathways in mediating expression of these two molecules. Rat proximal tubular cells (NRK52E) were stimulated with TGF-beta1 to induce VEGF-A and TSP-1 synthesis. To clarify roles of receptor-activated Smads (R-Smads), we blocked Smad signaling using overexpression of the inhibitory Smad, Smad7, and by using fibroblasts from wild-type or knockout mice. To confirm the antiantigenic role of Smads, soluble Flt-1 regulation in response to TGF-beta1 was also examined. In addition, the effect of conditioned media from NRK52E and Smad knockout cells was examined on endothelial cell proliferation.Results. Induction of VEGF-A and TSP-1 by TGF-beta1 in NRK52E cells was associated with activation of pathway-restricted R-Smads (Smad2 and 3) and blocking these Smads by overexpression of Smad7 blocked their induction. By using of Smad knockout cells, Smad3 was shown to have a key role in the stimulation of VEGF-A expression whereas Smad2 was critical for TSP-1 expression. Consistent with the hypothesis that Smad2 has an antiangiogenic function, we also demonstrated that Smad2, but not Smad3, mediated the expression of VEGF-A antagonist, soluble VEGF-A receptor sFlt-1, in response to TGF-beta1. Conditioned media from NRK52E, which was stimulated by TGF-beta1 for 24 hours, did not induce endothelial cell proliferation. However, conditioned media from Smad2 knockout induced endothelial cell proliferation, whereas endothelial cell proliferation was inhibited by Smad3 knockout-derived conditioned media.Conclusion. R-Smads have distinct roles in mediating the expression of pro- and antiangiogenic growth factors in response to TGF-beta1.