Genetic control of C. elegans gastrulation

描述（由申请人提供）：原肠胚形成是早期发育的关键时期，细胞在胚胎内根据它们将成为的东西在空间上组织起来。必须密切控制原肠形成的细胞运动，以防止胚胎组织中可能导致出生缺陷或流产的灾难性缺陷，但我们对如何控制原肠形成知之甚少。特别是，尽管从几个模式物种的研究中可以清楚地看出，细胞命运规范基因可以指导原肠形成运动，但控制原肠形成的下游效应物的身份和功能在很大程度上是未知的。本提案的具体目标是鉴定和表征在细胞命运规范基因下游起作用以控制原肠胚运动的基因。我们的长期目标是全面了解细胞命运规范基因、原肠形成控制基因、基本细胞骨架和细胞极性蛋白如何共同诱导、影响和协调原肠形成运动。在本研究中，我们利用秀丽隐杆线虫胚胎的光学清晰度和遗传可操纵性来鉴定和表征原肠形成控制基因。由于保守的细胞机制似乎在原肠胚形成过程中起作用，我们的研究利用秀丽隐杆线虫的优势，独特地补充了其他脊椎动物和无脊椎动物模式生物的研究。秀丽隐杆线虫内胚层细胞的原肠胚形成是由转录因子END-1和END-3触发的，这两个转录因子也是内胚层形成所必需的。然而，END-1和END-3对原肠胚形成重要的下游效应物尚不清楚。在初步研究中，我们进行了微阵列实验，以鉴定一组以前未知的END效应基因。在这里，我们提出了遗传和细胞生物学实验来鉴定和表征那些对原肠形成重要的蛋白，并提出了额外的实验来鉴定可能与END效应物结合以控制原肠形成的肌动球蛋白调节蛋白。最后，我们提出实验来确定Wnt信号是否如最近提出的那样在促进原肠形成中起直接作用，或者Wnt信号是否通过其指定内胚层的已知作用间接促进原肠形成。这些实验将为理解秀丽隐杆线虫原肠形成的遗传逻辑提供第一个基础。由于原肠胚形成的许多细胞生物学事件是保守的，我们预计我们的发现-以及未来的研究将由此产生-将导致更好地理解人类胚胎发育的这个关键而神秘的阶段。公共卫生相关性：原肠胚形成是人类胚胎发育的一个关键阶段，当基本身体计划通过受调节的细胞运动建立时。本研究的目的是确定原肠形成细胞运动的重要基因，并了解这些基因的功能。这些研究将有助于了解人类出生缺陷和流产的原因，这些缺陷和流产是由异常泌乳引起的。

DESCRIPTION (provided by applicant): Gastrulation is a critical time in early development when cells organize themselves spatially within the embryo according to what they will become. The cell movements of gastrulation must be intimately controlled to prevent catastrophic defects in organization of the embryo that can cause birth defects or miscarriage, yet we know little about how gastrulation control is effected. In particular, although it is clear from work in several model species that cell fate specification genes can direct gastrulation movements, the identities and functions of the downstream effectors controlling gastrulation are largely unknown. The specific goal of this proposal is to identify and characterize genes that function downstream of cell fate specification genes to control gastrulation movements. Our long-term goal is to have a complete picture of how cell fate specification genes, gastrulation control genes, and basic cytoskeletal and cell polarity proteins function together to induce, effect, and coordinate gastrulation movements. In this proposal, we take advantage of the optical clarity and genetic manipulability of the C. elegans embryo to identify and characterize gastrulation control genes. Because conserved cellular mechanisms appear to operate during gastrulation, our studies take advantage of the strengths of C. elegans to uniquely complement studies in other vertebrate and invertebrate model organisms. Gastrulation of C. elegans endodermal cells is triggered by the transcription factors END-1 and END-3, which are also required for endoderm specification. However, downstream effectors of END-1 and END-3 important for gastrulation are unknown. In preliminary studies, we have performed microarray experiments to identify a set of previously unknown END effector genes. Here, we propose genetic and cell biological experiments to identify and characterize those important for gastrulation, and additional experiments to identify the actomyosin regulatory proteins that likely interface with the END effectors to control gastrulation. Finally, we propose experiments to determine whether Wnt signaling has a direct role in promoting gastrulation, as recently proposed, or whether Wnt signaling contributes to gastrulation indirectly through its known role in specifying endoderm. These experiments will provide the first foundation for understanding the genetic logic of C. elegans gastrulation. Because many of the cell biological events of gastrulation are conserved, we anticipate that our findings - and future studies that arise from them - will lead to a better understanding of this critical yet mysterious stage of human embryonic development. PUBLIC HEALTH RELEVANCE: Gastrulation is a critical stage in human embryonic development when the basic body plan is established through regulated cell movements. The goal of this proposal is to identify the genes important for gastrulation cell movements and learn how these genes function. These studies will help in understanding the cause of human birth defects and miscarriages that result from abnormal gastrulation.