Ethanol-induced Lower Jaw Loss in Bmp Signaling Pathway Mutants

描述（由申请人提供）：胎儿酒精谱系障碍（FASD）描述了一系列乙醇诱导的发育缺陷，包括颅面畸形，如下颌发育不全。它影响每年在美国出生的100名儿童中的大约1名。虽然胎儿暴露于酒精会导致FASD，但这些酒精诱导的颅面缺陷背后的遗传学事实上还不清楚。包括下颌在内的大部分颅面骨骼都是由颅神经嵴细胞产生的。神经嵴细胞和上皮组织之间复杂的相互作用对颅面形态发生非常重要。这些相互作用由骨形态发生蛋白（Bmp）信号通路等协调。使用斑马鱼的初步数据表明，Bmp信号通路的成员是乙醇敏感位点。虽然bmp 2b纯合突变胚胎在颅面发育开始之前死亡，但bmp 2b杂合胚胎和bmp 4纯合突变胚胎（统称为Bmp途径突变体）经历正常颅面发育。然而，BMP途径突变体显示出乙醇诱导的下颌Meckel软骨缺陷。鞘氨醇受体s1 pr 2的突变，由于破坏前内胚层的形态发生和随后的口腔外胚层缺陷，导致与美克尔软骨惊人相似的缺陷。研究结果表明，假设乙醇破坏前内胚层形态发生BMP途径突变体导致缺陷的口腔外胚层和随后的颅面发育。在本提案的具体目标1中，1）将观察乙醇如何干扰Bmp途径突变体中内胚层形态发生期间的细胞行为，2）通过生成标记内胚层和口腔外胚层的双转基因系，将直接观察内胚层和口腔外胚层之间的相互作用。在具体目标2中，BMP通路信号传导在下颌图案中的机制将通过移植实验和原位标记分析来确定。在特定目标3中，将对从正向遗传筛选中回收的乙醇敏感性突变体进行作图，并表征总体乙醇敏感性。总的来说，该应用程序将提供更深入的了解基因-乙醇相互作用，导致FASD颅面缺陷的变异性。此外，由于斑马鱼和人类之间基因功能的保守性，这项工作将直接转化为人类群体中候选基因的研究，并更好地诊断和治疗FASD。

DESCRIPTION (provided by applicant): Fetal Alcohol Spectrum Disorder (FASD) describes a wide array of ethanol-induced developmental defects, including craniofacial dysmorphology, such as lower jaw hypoplasia. It affects approximately 1 in 100 children born in the United States each year. Although fetal exposure to alcohol causes FASD, virtually nothing of the genetics behind these ethanol-induced craniofacial defects is understood. The majority of the craniofacial skeleton, including the lower jaw, is generated by cranial neural crest cells. Complex interactions between neural crest cells and epithelial tissues are important for craniofacial morphogenesis. These interactions are orchestrated by, among others, the Bone Morphogenic Protein (Bmp) signaling pathway. Preliminary data using zebrafish demonstrate that members of the Bmp signaling pathway are ethanol-sensitive loci. While bmp2b homozygous mutant embryos die before craniofacial development initiates, bmp2b heterozygous embryos and bmp4 homozygous mutant embryos (together termed Bmp-pathway mutants) undergo normal craniofacial development. However, Bmp-pathway mutants display ethanol-induced defects to Meckel's cartilage the lower jaw. Mutation of the sphingosine receptor, s1pr2, causes strikingly similar defects to Meckel's cartilage due to disrupted morphogenesis of the anterior endoderm and subsequent defects to the oral ectoderm. The findings suggest the hypothesis that ethanol disrupts anterior endoderm morphogenesis in Bmp-pathway mutants resulting in defects in the oral ectoderm and subsequent craniofacial development. In Specific Aim 1 of this proposal, 1) how ethanol perturbs cell behaviors during endodermal morphogenesis in Bmp-pathway mutants will be visualized and 2) the interaction between the endoderm and oral ectoderm will be directly visualized through generation of a double transgenic line that labels the endoderm and the oral ectoderm. In Specific Aim 2, the mechanism of Bmp-pathway signaling in patterning the lower jaw will be determined through transplantation experiments and in situ marker analyses. In Specific Aim 3, an ethanol- sensitive mutant recovered from a forward genetic screen will be mapped and the overall ethanol sensitivity characterized. Overall, this application will provide greater insight into the gene-ethanol interactions that lead to the variability of craniofacial defects in FASD. In addition, because of the conservation of gene function between zebrafish and humans, this work will directly translate to studies of candidate genes in human populations and allow better for diagnosis and treatment of FASD.