NFkB Targets and Neural Crest Development

神经脊是脊椎动物的创新，有时被称为第四胚层；神经脊产生迁移细胞，分化为软骨、黑素细胞、周围神经系统和心脏流出道。神经脊缺陷涉及400多个人类综合征，并导致颅面、心脏、色素沉着、外周和中枢神经系统缺陷。我们的重点一直是环境调节和发育重要的转录因子NFKB及其在早期胚胎中的调控靶点。NFkB的激活与乙醇等环境因素的致畸作用有关。影响神经脊的早期胚胎缺陷是与胎儿酒精综合征(FAS)相关的神经、颅面和牙齿畸形，以及不那么严重但仍然严重的酒精相关神经发育障碍(ARND)和酒精相关出生缺陷(ARBD)。这项提案的目的是更好地了解这些缺陷的分子性质，特别是涉及NFKB监管目标的缺陷。以爪蛙为模型系统，我们发现NFKB调控着TWIST、SNAI/1和SNAI/2(SLUG)RNA的水平。Twist编码一个bHLH转录因子，而SNAI/1和SNAI/2编码相关的锌指转录因子Snail1和Snail2，这三个转录因子也与肿瘤转移有关。在早期胚胎中，Twist、Snail1和Snail2相互调节彼此的表达，是中胚层形成和随后神经脊的形成、存活和分化所必需的。令人惊讶的是，可以挽救彼此失去的功能表型。有证据表明，类似的相互作用网络可能在小鼠早期胚胎中活跃，这证明了这一系统与人类胚胎/神经脊缺陷的相关性。鉴于这个项目的时间跨度缩短了(两年)，我们将集中精力研究两个修订后的目标，并将使用ebraFish进行的比较和细胞迁移研究推迟到以后的时间。通过利用X.laevis系统的实验优势，我们将：1)定义TWIST、SNAI/1和SNAI/2在神经脊诱导、存活和分化中独特和互补的中胚层作用；2)在神经脊规范中确定中胚层信号的时间和空间需求。总的来说，这些观察结果对于理解分子和感应网络的行为，特别是预防和/或改善神经脊缺陷具有重要的意义。

The neural crest is a vertebrate innovation, sometimes referred to as the fourth germ layer; the neural crest gives rise to migrating cells that differentiate into cartilage, melanocytes, the peripheral nervous system, and the outflow tract of the heart. Defects in the neural crest are involved in over 400 human syndromes and result in craniofacial, heart, pigmentation, peripheral and central nervous system defects. Our focus has been on the environmentally regulated and developmentally important transcription factor NFKB and its regulatory targets in the early embryo. NFKB activation has been implicated in the teratogenic effects of environmental factors such as ethanol. Early embryonic defects impacting the neural crest underlie the neurological, craniofacial, and dental malformations associated with Fetal Alcohol Syndrome (FAS) and the less severe, but still significant alcohol-related neurodevelopmental disorder (ARND) and alcoholrelated birth defects (ARBD). The goal of this proposal is to better understand the molecular nature of these defects, particularly those involving the regulatory targets of NFKB. Using the clawed frog Xenopus as a model system, we found that NFKB regulates the levels of twist, snai/1, and snai/2(slug) RNA levels. twist encodes a bHLH transcription factor, while snai/1 and snai/2 encode the related zinc-finger transcription factors Snail1 and Snail2; these three transcription factors are also implicated tumor metastasis. In the early embryo, Twist, Snail1, and Snail2 regulate one another's expression and are required for the formation of mesoderm and the subsequent formation, survival, and differentiation of the neural crest. Surprisingly, can rescue each other's loss of function phenotypes. There is evidence that a similar network of interactions may be active in the early mouse embryo, arguing for the relevance of this system to human embryonic/neural crest defects. In light of the shortened (2 year) timespan available for this project, we will concentrate our efforts on two revised aims and will delay our comparative and cell migration studies using ebrafish until a later time. By exploiting the experimental strengths of the X. laevis system we will i) define the unique and complementary mesodermal roles of twist, snai/1, and snai/2 on neural crest induction, survival, and differentiation and ii) identify the temporal and spatial requirement for mesodermal signals in neural crest specification. Together these observation should have important implications for understanding the behavior of molecular and inductive networks in general and the prevention and/or amelioration of neural crest defects in particular.