Peng Yin, Song Lanying, Li Ding, Kesterson Robert, Wang Jianbo, Wang Lizhong, Rokosh Gregg, Wu Bingruo, Wang Qin, Jiao Kai
Department of Genetics, The University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Department of Cell, Developmental and Integrative Biology, The University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Cardiovasc Res. 2016 Nov 1;112(2):532-542. doi: 10.1093/cvr/cvw200.
Bone morphogenetic protein (BMP) signalling plays a key role in regulating the development of the atrioventricular (AV) septum and valves; however, the molecules that mediate the complex activities of BMP signalling are not fully understood. The major goal of this study is to identify the critical downstream regulatory targets of BMP signalling in AV cushions, which are precursors of the AV septum and valves.
We established a conditional immortal AV cushion mesenchymal cell line, tsA58-AVM. Using this line, we observed that the expression of is upregulated by BMP stimulation through microarray analysis. is required for BMP-upregulated migration of tsA58-AVM cells. To reveal the role of , we established the mouse line and specifically inactivated in endocardial cells (by ) when cushion mesenchymal cells started to form. We observed a hypocellular AV cushion defect in mutant hearts at early stages (E9.25, E9.5). The defect was resolved at a later stage, most likely due to compensation by increased in mutant AV cushions. Furthermore, our culturing and transgenic studies collectively suggest that SEMA6D activates Rho through PLXNA1-FARP1 to promote cushion mesenchymal cell formation.
We demonstrate for the first time that is a target of BMP signalling and that Semaphorin signalling is essential for the initiation of cushion mesenchymal cell formation in the AV canal. Our study reveals a novel BMP- -Rho axis regulating AV cushion development.
骨形态发生蛋白（BMP）信号传导在调节房室（AV）间隔和瓣膜的发育中起关键作用；然而，介导BMP信号复杂活性的分子尚未完全明确。本研究的主要目的是确定BMP信号在AV垫中的关键下游调控靶点，AV垫是AV间隔和瓣膜的前体。
我们建立了一种条件永生化的AV垫间充质细胞系，tsA58-AVM。利用该细胞系，通过微阵列分析我们观察到BMP刺激可上调某基因的表达。该基因是BMP上调tsA58-AVM细胞迁移所必需的。为揭示该基因的作用，我们建立了该基因敲除小鼠品系，并在垫间充质细胞开始形成时在内皮细胞中特异性敲除该基因（通过某种技术）。我们观察到突变体心脏在早期阶段（E9.25，E9.5）存在细胞减少的AV垫缺陷。该缺陷在后期得到解决，最可能是由于突变体AV垫中该基因表达增加的补偿作用。此外，我们的细胞培养和转基因研究共同表明，SEMA6D通过PLXNA1-FARP1激活Rho以促进垫间充质细胞形成。
我们首次证明该基因是BMP信号的靶点，并且信号素信号对于AV管中垫间充质细胞形成的起始至关重要。我们的研究揭示了一条调节AV垫发育的新型BMP-该基因-Rho轴。 （注：原文中部分基因名称未给出具体中文，用“某基因”等表示）
