The evolution of retinoic acid signaling in animals: functional insights from a mollusc embryo

维甲酸是一种具有生物活性的维生素A，它作为细胞间的信号，对人类发育至关重要。维甲酸信号被认为是脊椎动物的独特特征。然而，最近在多个无脊椎动物基因组中发现了控制维甲酸信号的基因，但尚不清楚维甲酸信号在这些动物中起什么作用。这个项目利用了最近发现的维甲酸信号在蜗牛胚胎中的作用。该小组发现，对维甲酸信号的几种不同成分的实验操作影响了发育中的胚胎中的相同结构，表明这些不同成分在一条途径上协同工作，就像在脊椎动物中所做的那样。这个项目有望对脊椎动物外的维甲酸信号产生最全面的理解，并改变我们对这一途径如何在进化中产生的理解。该项目还将有助于培养本科生和研究生水平的科学家，推广到当地的K-12学生，并为发育生物学的本科课程提供开源教学资源。为了确定腹足类Tritia(又名Ilyanassa)胚胎中维甲酸(RA)途径的组成和作用，研究小组将首先利用初步数据中的RA效应知识对另外17个假定的RA途径成分基因进行功能筛选，然后进一步测试具有预期表型的基因，以便与已知成分进行功能相互作用。同时，他们将测量不同发育阶段内源性RA异构体的水平。在第二组实验中，他们将专门测试RA中断对神经系统发育的影响，神经系统是该通路在脊椎动物中的关键作用。在神经发生中的作用得到了其他无脊椎动物的支持，因此这将是对这一比较工作的重要贡献。这些实验将进一步加深对RA角色的理解，并将这些结果与新生的RA比较文献相结合。在最后一组实验中，他们将测试几个特定的RA功能机制模型，包括系统是否对不同转录水平的不同配体剂量做出反应。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Retinoic acid is a biologically active version of Vitamin A that acts as a signal between cells and is crucial for human development. Retinoic acid signaling was thought to be a unique characteristic of the vertebrates. Recently however, the genes that control retinoic acid signaling have been found in multiple invertebrate genomes, but it is not clear what retinoic acid signaling is doing in these animals. This project takes advantage of recently discovered roles of retinoic acid signaling in a snail embryo. This group has found that experimental manipulations of several different components of retinoic acid signaling impacted the same structures in the developing embryo, indicating that these different components are working together in a pathway as they do in vertebrates. This project is expected to generate the most comprehensive understanding of retinoic acid signaling outside of vertebrates, and change our understanding of how this pathway arose in evolution. This project will also contribute to the training of undergraduate and graduate level scientists, outreach to local K-12 students, and an open-source teaching resource for undergraduate courses in developmental biology.To characterize the components and roles of the retinoic acid (RA) pathway in the embryo of the gastropod Tritia (aka Ilyanassa), the research team will first use the knowledge of RA effects from preliminary data to carry out a functional screen of 17 additional putative RA pathway component genes, then further test genes with the expected phenotypes for functional interactions with known components. In parallel, they will measure levels of endogenous RA isomers across developmental stages. In a second set of experiments, they will specifically test the effect of RA disruption on the development of the nervous system, a key role of the pathway in vertebrates. A role in neurogenesis has some support from other invertebrates, so this will be an important contribution to that comparative work. These experiments will further the understanding of the roles of RA, and integrate these results with the nascent comparative RA literature. In a final set of experiments, they will test several specific models for the mechanisms of RA function, including whether the system responds to different ligand dosages with different transcription levels.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.