Mesoderm Specification in C. elegans

发育生物学的一个中心问题是解释在动物三个基本胚层（内胚层、中胚层和外胚层）的产生中，胚胎发育期间组织和细胞类型多样性是如何产生的。 线虫C. elegans是探索细胞命运特化机制和阐明相关分子参与者的极好模型系统。 在胚胎发育早期，C.线虫中内胚层前体EMS是由GATA样转录因子MED-1和MED-2的激活所指定的。 MED与保守的Wnt信号传导途径一起起作用，以指定EMS子细胞中的中胚层（MS）或内胚层（E）命运。 虽然对内胚层的了解很多，但对更复杂的中胚层谱系是如何指定的知之甚少。 Maduro博士的实验室有兴趣阐明中胚层调控基因网络，并了解Wnt途径如何限制MED靶基因对MS细胞的激活。 他们确定了MED-1的新结合位点，并利用该位点鉴定了19个新的候选靶基因，其中许多已被证实在中胚层或内胚层中表达。 该提案旨在表征这些靶基因并研究它们通过MED-1和Wnt途径的调节。 首先，他们将完成候选MED-1靶点的表达分析，重点是预测的转录因子，将从遗传学上评估它们的发育作用。 其次，他们将分析MED-1的结构-功能特性，以更多地了解这种新型调节剂如何在中胚层规范中发挥作用。 第三，他们将表征MED靶基因的差异中胚层与内胚层激活的基础，这些基因通过明显新颖的基于Wnt的机制进行调节。 由于候选MED靶基因的同源物在其他系统中的中胚层中发挥作用，并且由于Wnt通路在整个后生动物（包括人类癌症）的发育重要过程中发挥作用，这项工作有望揭示有关早期胚胎发育和基因调控的新原则，这些原则具有广泛的适用性。 拟议的工作将是在加州大学滨江（UCR）的两名女博士候选人的研究培训的核心。 来自UCR种族多元化学生团体的本科生将参与该项目。 马杜罗博士将通过教授发育生物学的研究生和本科课程来整合教育和研究。

A central problem in developmental biology is to account for how tissue and cell type diversity arises during embryonic development in the generation of the three fundamental germ layers in animals (endoderm, mesoderm and ectoderm). The nematode, C. elegans, has been an excellent model system in which to explore mechanisms of cell fate specification and to elucidate the molecular players involved. In early mbryogenesis, the C. elegans mesendodermal precursor EMS is specified by the activation of the GATA-like transcription factors MED-1 and -2. The MEDs function with the conserved Wnt signaling pathway to specify either mesoderm (MS) or endoderm (E) fate in the EMS daughter cells. While much is known about endoderm, very little is known about how the more complex mesoderm lineage is specified. The laboratory of Dr. Maduro is interested in elucidating the mesodermal regulatory gene network and understanding how the Wnt pathway restricts activation of MED target genes to the MS cell. They have determined the novel binding site of MED-1 and used this site to identify 19 new candidate target genes, many of which have been confirmed to be expressed in mesoderm or endoderm. This proposal aims to characterize these target genes and study their regulation by MED-1 and the Wnt pathway. First, they will complete the expression analysis of the candidate MED-1 targets, and with emphasis on the predicted transcription factors, their developmental roles will be assessed genetically. Second, they will analyze the structure-function properties of MED-1 to learn more about how this novel regulator functions in mesoderm specification. Third, they will characterize the basis for differential mesodermal vs. endodermal activation of MED target genes that are regulated through an apparently novel Wnt-based mechanism. As homologs of candidate MED target genes function in mesoderm in other systems, and as the Wnt pathway functions in developmentally important processes throughout metazoa (including cancer in humans), this work promises to reveal new principles about early embryonic development and gene regulation that are widely applicable.Broader impacts: This is the first grant for a beginning investigator of Hispanic descent. The work proposed will be central to the research training of two female PhD candidates at UC Riverside (UCR). Undergraduates drawn from UCR's ethnically-diverse student body will participate in the project. Dr. Maduro will integrate education and research by teaching graduate and undergraduate courses in developmental biology.