Bmp signaling represses Vegfa to promote outflow tract cushion development
Bmp signaling represses Vegfa to promote outflow tract cushion development
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DOI：
10.1242/dev.097360
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发表时间：
2013-08-15
期刊：
影响因子：
4.6
通讯作者：
Martin, James F.
中科院分区：
文献类型：
--
作者：
Bai, Yan;Wang, Jun;Martin, James F.
先天性心脏病 (CHD) 是一种毁灭性异常疾病，影响约 1% 的活产婴儿。流出道（OFT）缺陷在人类冠心病中占很大比例。我们通过有条件地删除第二心区 (SHF) 中的 Bmp4 和 Bmp7 来研究小鼠 OFT 发育中的 Bmp 信号传导。 SHF Bmp4/7 缺陷导致上皮间质转化 (EMT) 缺陷和心脏神经嵴进入减少，从而导致持续性动脉干。使用候选基因方法，我们发现 Vegfa 在 Bmp4/7 突变体心脏中上调。为了确定 Vegfa 是否是 EMT 过程中的下游 Bmp 效应子，我们检查了 Vegfa 是否受 Bmp 受体调节的 Smad 转录调节。我们的研究结果表明，Smad 直接与 Vegfa 染色质结合并抑制 Vegfa 转录活性。我们还发现 Vegfa 是 miR-17-92 簇的直接靶标，该簇也受到 SHF 中 Bmp 信号传导的调节。 miR-17-92 的删除显示出与 Bmp4/7 SHF 删除相似的表型。为了直接解决 Bmp 介导的 EMT 中 Vegfa 抑制的功能，我们对 Bmp4/7 和 miR-17-92 突变心脏进行了离体外植体培养。 Bmp4/7 双条件敲除（dCKO；Mef2c-Cre；Bmp4/7f/f）和 miR-17-92 无效的外植体中 EMT 有缺陷。通过拮抗外植体中的 Vegfa 活性，在 Bmp4/7 dCKO 和 miR-17-92 无效培养物中挽救了 EMT。此外，miR-17-92的过度表达部分抑制了Bmp4/7突变胚胎中的EMT缺陷。我们的研究表明，OFT 中的 Vegfa 水平受到 Smad 和 microRNA 依赖性途径的严格控制，以调节 OFT 的发育。
Congenital heart disease (CHD) is a devastating anomaly that affects similar to 1% of live births. Defects of the outflow tract (OFT) make up a large percentage of human CHD. We investigated Bmp signaling in mouse OFT development by conditionally deleting both Bmp4 and Bmp7 in the second heart field (SHF). SHF Bmp4/7 deficiency resulted in defective epithelial to mesenchymal transition (EMT) and reduced cardiac neural crest ingress, with resultant persistent truncus arteriosus. Using a candidate gene approach, we found that Vegfa was upregulated in the Bmp4/7 mutant hearts. To determine if Vegfa is a downstream Bmp effector during EMT, we examined whether Vegfa is transcriptionally regulated by the Bmp receptor-regulated Smad. Our findings indicate that Smad directly binds to Vegfa chromatin and represses Vegfa transcriptional activity. We also found that Vegfa is a direct target for the miR-17-92 cluster, which is also regulated by Bmp signaling in the SHF. Deletion of miR-17-92 reveals similar phenotypes to Bmp4/7 SHF deletion. To directly address the function of Vegfa repression in Bmp-mediated EMT, we performed ex vivo explant cultures from Bmp4/7 and miR-17-92 mutant hearts. EMT was defective in explants from the Bmp4/7 double conditional knockout (dCKO; Mef2c-Cre; Bmp4/7f/f) and miR-17-92 null. By antagonizing Vegfa activity in explants, EMT was rescued in Bmp4/7 dCKO and miR-17-92 null culture. Moreover, overexpression of miR-17-92 partially suppressed the EMT defect in Bmp4/7 mutant embryos. Our study reveals that Vegfa levels in the OFT are tightly controlled by Smad-and microRNA-dependent pathways to modulate OFT development.