Li J, Molkentin J D, Colbert M C
Division of Molecular Cardiovascular Biology, Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA.
Dev Biol. 2001 Apr 15;232(2):351-61. doi: 10.1006/dbio.2001.0203.
Retinoic acid (RA), a potent teratogen, produces a characteristic set of embryonic cardiovascular malformations similar to those observed in neural crest ablated avians. While the effects of RA on neural crest are well described, the molecular mechanism(s) of RA action on these cells is less clear. The present study examines the relationship between RA and mitogen-activated protein kinase signaling in neural crest cells and demonstrates that c-Jun N-terminal kinase (JNK) activation is severely repressed by RA. RA suppressed migration and proliferation of primary cultures of mouse neural crest cells treated in vitro as well as from animals treated in vivo. On Western blots, JNK activation/phosphorylation in neural crest cultures was reduced, while neither extracellular signal-regulated kinase (ERK) nor p38 pathways were affected. Both the dose-dependent stimulation of neural crest outgrowth and JNK phosphorylation by platelet-derived growth factor AA, which promotes outgrowth but not proliferation of neural crest cultures, were completely abrogated by RA. To establish the relevance of the JNK signaling pathway to cardiac neural crest migration, dominant negative adenoviral constructs were used to inhibit upstream activation of JNK or c-Jun downstream responses. Both adenoviral constructs markedly reduced neural crest cell outgrowth, while a dominant negative inhibitor of the p38 pathway had no effect. These data demonstrate that the JNK signaling pathway and c-Jun activation are critical for cardiac neural crest outgrowth and are potential targets for the action of RA.
视黄酸（RA）是一种强效致畸剂，会产生一系列特征性的胚胎心血管畸形，类似于在神经嵴消融的鸟类中观察到的畸形。虽然RA对神经嵴的影响已有详细描述，但其作用于这些细胞的分子机制尚不清楚。本研究探讨了RA与神经嵴细胞中丝裂原活化蛋白激酶信号传导之间的关系，并证明RA会严重抑制c-Jun氨基末端激酶（JNK）的激活。RA抑制了体外处理的小鼠神经嵴细胞原代培养物以及体内处理的动物的神经嵴细胞的迁移和增殖。在蛋白质免疫印迹分析中，神经嵴培养物中的JNK激活/磷酸化水平降低，而细胞外信号调节激酶（ERK）和p38信号通路均未受影响。血小板衍生生长因子AA对神经嵴生长的剂量依赖性刺激和JNK磷酸化，可促进神经嵴培养物的生长但不促进其增殖，均被RA完全消除。为了确定JNK信号通路与心脏神经嵴迁移的相关性，使用显性负性腺病毒构建体抑制JNK的上游激活或c-Jun的下游反应。两种腺病毒构建体均显著减少了神经嵴细胞的生长，而p38信号通路的显性负性抑制剂则没有效果。这些数据表明，JNK信号通路和c-Jun激活对于心脏神经嵴的生长至关重要，并且是RA作用的潜在靶点。
