Using Frog Faces to Better Understand Clefts in the Primary Palate

描述（申请人提供）：大多数关于面部的研究集中在次上颚，而对初级上颚的了解相对较少。因此，本实验室的主要目标是填补这一领域的重要知识空白，并进一步了解初级上颚的形成和有关该结构的缺陷，如中口面裂。为此，我们开发了一个创新的模型系统，使用非洲爪蟾来研究口腔面部发育。我们发现维甲酸信号在调节面部突出的生长和收敛中的新作用，这在哺乳动物中是保守的。此外，在发育的特定时间干扰这一信号通路，会导致初级腭裂，与人类面部中裂非常相似。这种面部裂缝虽然罕见，但也与许多人类综合症有关。此外，初级上颚发育的小紊乱被认为是次级上颚裂的潜在原因。因此，我们对原发性腭裂发育的研究可能对人类腭裂的治疗干预措施的发展和预防具有重要影响。我们发表的和初步的研究已经促使我们形成这样的假设：维甲酸信号调节同源盒基因、表观遗传调节剂和细胞周期调节剂，这些基因聚合在一起，最终控制形成初级上颚的面部组织的细胞增殖。我们在目标1和目标2中验证了这一假设，我们结合了现代分子分析和经典胚胎学，特别是利用面部移植和形态计量学分析。由于口腔面部发育是复杂的，许多因素都可能导致该区域的出生缺陷，因此更好地了解初级上颚是如何发育的至关重要。此外，确定能够影响内源性发育途径的环境毒素也很重要。在目的3中，我们建议使用化学筛选作为一种无偏倚的方法来发现初级腭裂发育的新机制，并测试环境毒素是否会加剧中位腭裂。

DESCRIPTION (provided by applicant): Most research concerning the face focuses on the secondary palate, while relatively less is known about the primary palate. Therefore, the broad goals of the lab are to fill this significant knowledge gap in the field and further our understanding of primary palate formation and defects concerning this structure such as median orofacial clefts. To do so we have developed an innovative model system using Xenopus laevis to study orofacial development. We have uncovered novel roles for retinoic acid signaling in regulating growth and convergence of the facial prominences in this species that are conserved in mammals. Moreover, perturbing this signaling pathway, at a specific time in development, results in a cleft in the primary palate that closely resembles human median facial clefts. Such facial clefts while rare, are also associated with a number of human syndromes. Moreover, small disturbances in the development of the primary palate have been postulated to be an underlying cause of clefts in the secondary palate. Therefore, our studies of primary palate development could have significant impact on the development of therapeutic interventions and prevention of facial clefts in humans. Our published and preliminary studies have prompted us to form the hypothesis that retinoic acid signaling regulates homeobox genes, epigenetic modulators and cell cycle regulators that converge to ultimately control cell proliferation of the facial tissues that form the primary palate. We test this hypothesis in aims 1 and 2 where we combine modern molecular assays and classical embryology, notably utilizing face transplants and morphometric analyses. Since orofacial development is complex and many factors can contribute birth defects in this region a better understanding of how the primary palate develops is critical. In addition, it is also essential to identify environmental toxins that can influence he endogenous developmental pathways. In the aim 3 we propose to use chemical screens as an unbiased method to find novel mechanisms in primary palate development and to test whether environmental toxins can exacerbate median clefts.