Analysis of teratogenic mechanisms of retinoic acid on mammalian craniofacial morphogenesis---as models for human congenital anomalies

视黄酸对哺乳动物颅面形态发生的致畸机制分析——作为人类先天畸形模型

基本信息

批准号：
06671805
负责人：
YAMASHITA Noriko
金额：
$ 1.34万
依托单位：
Tokyo Medical and Dental University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

Retinoic acid (RA), a natural metabolite of vitamin A,is essential for normal mammalian development. However, embryos exhibit anomalies also by excess vitamin A and other natural and synthesized retinoids including RA.Craniofacial malformations experimentally induced with retinoids in laboratory animals are regarded as models for human congenital anomalies such as Treacher-Collins and Di George syndromes. Since cranial neural crest cells play important roles in development of head and face, here we have established in vitro conditions which reproducibly induce typical phenotypes of craniofacial abnormalities and examined behavior of the crest cells.9.0 day and 9.5 day rat embryos were treated in vitro with all-trans-RA for 6 hours and further cultured up to the stage corresponding to 11.5 day in vivo embryos. The former treatment induced posteriorization in the CNS and pharyngeal arches, while the latter treatment resulted in fusion of the first and second arches as well as that of the trigeminal and acousticofacial ganglia. Interestingly, DiI labeling study revealed that crest cells derived from the anterior and preotic hindbrain do not mix within the fused arch. It supports the idea that differential identities of the crest cell populations are still maintained. In contrast, crest cells from the anterior hindbrain ectopically migrate into the second arch in cultured rat embryos treated at 9.0day, suggesting that RA affected not only the identity of the hindbrain neuroectoderm but also that of the crest cells derived from the hindbrain. Thus, RA affected migration of crest cells and features of cranial nerves in a stage-dependent manner. Such stage dependency in RA's effects was also observed at the molecular level since the distribution pattern of CRABP-I protein was unchanged in the late-stage treatment but drastically altered in the early-stage treatment.

维生素A的天然代谢物视黄酸（RA）对于正常的哺乳动物发育至关重要。然而，胚胎也表现出异常的维生素A以及其他天然和合成的类维生素类动物，包括Ra.Craniofacial畸形在实验室动物中通过实验性诱导的颅面畸形被认为是人类先天性异常（如Treacher-Collins和Di George综合症）的模型。由于颅神经crest细胞在头部和脸部的发展中起着重要作用，因此我们建立了体外条件，可重复地诱导颅面异常的典型表型，并检查了Crest细胞的行为。9.0天和9.5天的大鼠胚胎在embry in and Trans-ra中进行了6个小时的体外处理，并进一步培养了11个小时，以进一步培养阶段。前者的治疗诱导中枢神经系统和咽弓的后侧化，而后一种治疗导致第一和第二弓以及三叉神经节和声学神经节的融合。有趣的是，DII标记研究表明，源自前后后的后脑的冠状细胞不会在熔融弓内混合。它支持这样的观念，即仍保持冠状细胞种群的差异身份。相反，来自前后脑的cr峰细胞在9.0天治疗的培养的大鼠胚胎中迁移到第二个弓形，这表明RA不仅影响了后后脑神经外胚层的身份，而且还影响了从后代衍生的crest细胞的身份。因此，RA以阶段依赖性方式影响了rest细胞的迁移和颅神经的特征。在分子水平上也观察到了这种阶段对RA作用的依赖性，因为在晚期治疗中，CrabP-I蛋白的分布模式不变，但在早期治疗中会发生巨大变化。