Wnt5a and Wnt11 inhibit the canonical Wnt pathway and promote cardiac progenitor development via the Caspase-dependent degradation of AKT
Wnt5a and Wnt11 inhibit the canonical Wnt pathway and promote cardiac progenitor development via the Caspase-dependent degradation of AKT
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DOI：
10.1016/j.ydbio.2014.11.015
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发表时间：
2015-02-01
影响因子：
2.7
通讯作者：
Cohen, Ethan David
中科院分区：
文献类型：
--
作者：
Bisson, Joseph A.;Mills, Bradley;Cohen, Ethan David
枯萎蛋白通过诱导β -连环蛋白依赖转录的典型信号通路调节细胞行为。现在认识到Wnt/ β -连环蛋白信号传导促进第二心场（SHF）祖细胞的扩张，最终产生大多数心肌细胞。然而，激活β -catenin也会导致SHF祖细胞的丢失，这突出了在心脏发育过程中精确控制β -catenin信号的必要性。我们最近报道了两个非规范Wnt配体，Wnt5a和Wnt11，协同作用来减弱规范Wnt信号，否则会破坏SHF。虽然这些数据揭示了这种抗典型Wnt5a/Wnt11信号在SHF发展中的重要作用，但这些配体抑制典型Wnt途径的机制尚不清楚。Wnt11先前被证明可以抑制β -连环蛋白，并通过激活一种新的凋亡无关的Caspases功能来促进心肌细胞成熟。与这些数据一致，我们现在表明Wnt5a和Wntll能够诱导胚胎干细胞（ES）和心脏分化的Caspase活性（-/-）；Wnt11（-/-）胚胎Caspase 3 （Casp3）活性降低。此外，在Casp3突变型ES细胞中，SHF标记物减少，而用Caspase抑制剂处理野生型ES细胞可阻断Wnt5a和Wnt11促进SHF基因表达的能力。这一发现与我们的体内研究一致，在体内研究中，给妊娠小鼠注射Caspase抑制剂可以降低妊娠胚胎中SHF标记物的表达。Caspase抑制还阻断了Wnt5a/Wnt11诱导的其他效应，包括抑制β -连环蛋白的表达和活性。有趣的是，通过Caspase依赖机制，Wnt5a/Wnt11处理分化的ES细胞降低了磷酸化Akt和总Akt，并且在处理过Caspase抑制剂的心脏中磷酸化Akt水平升高。令人惊讶的是，与Wnt5a/Wnt11治疗相比，抑制ES细胞中的Akt或PI3K同样有效地增加了SHF标志物。此外，Ala抑制恢复了Casp3突变ES细胞中SHF基因的表达。综上所述，这些发现表明Wnt5a/Wnt11抑制β -连环蛋白，通过caspase依赖性Akt降解促进SHF的发展。(C) 2014爱思唯尔公司版权所有。
Wilt proteins regulate cell behavior via a canonical signaling pathway that induces beta-catenin dependent transcription. It is now appreciated that Wnt/beta-catenin signaling promotes the expansion of the second heart field (SHF) progenitor cells that ultimately give-rise to the majority of cardiomyocytes. However, activating beta-catenin can also cause the loss of SHF progenitors, highlighting the necessity of precise control over beta-catenin signaling during heart development. We recently reported that two noncanonical Wnt ligands, Wnt5a and Wnt11, act cooperatively to attenuate canonical Wnt signaling that would otherwise disrupt the SHF. While these data reveal the essential role of this anti-canonical Wnt5a/Wnt11 signaling in SHF development, the mechanisms by which these ligands inhibit the canonical Wnt pathway are unclear. Wnt11 was previously shown to inhibit beta-catenin and promote cardiomyocyte maturation by activating a novel apoptosis-independent function of Caspases. Consistent with these data, we now show that Wnt5a and Wntll are capable of inducing Caspase activity in differentiating embryonic stem (ES) cells and that hearts from Wnt5a(-/-); Wnt11(-/-) embryos have diminished Caspase 3 (Casp3) activity. Furthermore, SHF markers are reduced in Casp3 mutant ES cells while the treatment of wild type ES cells with Caspase inhibitors blocked the ability of Wnt5a and Wnt11 to promote SHF gene expression. This finding was in agreement with our in vivo studies in which injecting pregnant mice with Caspase inhibitors reduced SHF marker expression in their gestating embryos. Caspase inhibition also blocked other Wnt5a/Wnt11 induced effects, including the suppression of beta-catenin protein expression and activity. Interestingly, Wnt5a/Wnt11 treatment of differentiating ES cells reduced both phosphorylated and total Akt through a Caspase-dependent mechanism and phosphorylated Akt levels were increased in the hearts Caspase inhibitor treated. Surprisingly, inhibition of either Akt or PI3K in ES cells was an equally effective means of increasing SHF markers compared to treatment with Wnt5a/Wnt11. Moreover, Ala inhibition restored SHF gene expression in Casp3 mutant ES cells. Taken together, these findings suggest that Wnt5a/Wnt11 inhibit beta-catenin to promote SHF development through Caspase-dependent Akt degradation. (C) 2014 Elsevier Inc. All rights reserved.