Cellular and molecular mechanisms of orofacial clefts

项目摘要/摘要 口腔裂是最常见的出生缺陷之一，每年影响约22万名新生儿。这个 口面部裂的原因和预防仍然知之甚少。我们已经发现LRP6介导的 Wnt/？-catenin信号通路是唇腭部形成和融合所必需的信号通路，它可能通过 MSX同源框基因的正向调节，并可能抑制维甲酸的合成 口面部原基中的酶。口面部发育既涉及口面部间充质扩张，也涉及口面部发育 外胚层/上皮融合过程。我们证明了面部功能的丧失或恢复 外胚层-连环蛋白信号阻止口面部原基的形成和图案化，这可能起作用 面部外胚层和面部前部的关键信号分子Fgf8的转录调控 神经脊(一个区域信号中枢)。腭裂所致的腭裂上皮的功能丧失或功能恢复 味觉。这些研究表明，在正常口腔面部过程中，Wnt/？-catenin信号活性受到严格调控 形态发生和Wnt/B-catenin信号的低或高活性可能导致口面部出生 缺陷。然而，Wnt/B-catenin信号通路在口腔颌面发育过程中的调控机制 仍然几乎是未知的，将在这项研究中解决。口腔裂可由基因突变引起 和/或环境因素。后者可能影响表观遗传过程，如DNA甲基化和 染色质修饰，在不改变基因组序列的情况下调节基因表达活性。 然而，口面部裂的表观遗传学机制仍然知之甚少。我们假设 表观遗传因子调节嘴唇/腭部形成和融合过程中适当的Wnt/？-catenin信号活动。 具体目标1将解决两个表观遗传调节因子的作用，如果它们不是，可能会导致口裂 监管得当。特定目标2将测试关键的Wnt/？连环蛋白的遗传互作和/或遗传挽救 口裂中的信号成分和表观遗传因素。具体目标3将检验这一假设 表观遗传调控Wnt/B-catenin信号可以预防突变动物模型中的口裂。 拟议研究的成功完成将为遗传和表观遗传学提供新的见解 口面部裂隙的机制，这可能转化为临床应用于治疗口面部出生缺陷 通过操纵关键的监管流程。

PROJECT SUMMARY/ABSTRACT Orofacial clefts are one of the most common birth defects, affecting about 220,000 newborns each year. The cause and prevention of orofacial clefts remain poorly understood. We have uncovered that the Lrp6-mediated Wnt/ß-catenin signaling pathway is required for lip and palate formation and fusion, which may act through positive regulation of the Msx homeobox-containing genes, and may repress a retinoic acid-synthesizing enzyme in the orofacial primordia. Orofacial development involves both orofacial mesenchymal expansion and ectodermal/epithelial fusion processes. We demonstrated that either loss- or gain-of-function of facial ectodermal ß-catenin signaling arrested the formation and patterning of orofacial primordia, which may act through transcriptional regulation of Fgf8, a critical signaling molecule in the facial ectoderm and anterior neural ridge (a regional signaling center). Loss- or gain-of-function of palatal epithelial ß-catenin caused cleft palate. These studies suggest that Wnt/ß-catenin signaling activity is tightly regulated during normal orofacial morphogenesis and that either hypo- or hyperactivity of Wnt/ß-catenin signaling may cause orofacial birth defects. However, the regulatory mechanism of Wnt/ß-catenin signaling pathway during orofacial development remains almost unknown and will be addressed in this study. Orofacial clefts can be caused by gene mutations and/or environmental factors. The latter may affect epigenetic processes, such as DNA methylation and chromatin modification, to regulate gene expression activities without altering the genomic sequence. Nevertheless, epigenetic mechanisms of orofacial clefts remain poorly understood. We hypothesize that epigenetic factors regulate appropriate Wnt/ß-catenin signaling activities for lip/palate formation and fusion. Specific Aim 1 will address the role of two epigenetic regulators that may lead to orofacial clefts if they are not properly regulated. Specific Aim 2 will test genetic interactions and/or the genetic rescue of key Wnt/ß-catenin signaling components and the epigenetic factors in orofacial clefts. Specific Aim 3 will test the hypothesis that epigenetic modulation of Wnt/ß-catenin signaling can prevent orofacial clefts in mutant animal models. Successful completion of the proposed research will provide new insights into the genetic and epigenetic mechanisms of orofacial clefts, which may translate into clinical applications to treat orofacial birth defects through manipulation of key regulatory processes.