Function of TOPLESS in Arabidopsis Embryonic Polarity

TOPLESS在拟南芥胚胎极性中的作用

• 批准号: 7489904
• 负责人: JEFFREY A LONG
• 金额: $ 38.56万
• 依托单位: SALK INSTITUTE FOR BIOLOGICAL STUDIES
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-27 至 2009-12-20
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7489904
• 关键词: Affect; Alleles; Animals; Apical; Arabidopsis; Biological Assay; Cells; Chimeric Proteins; DNA Binding Domain; Development; Development Polarity; Embryo; Embryonic Development; Enhancers; Ensure; Genes; Genetic; Genetic Transcription; Goals; High temperature of physical object; Histocompatibility Testing; Inherited; Lead; Learning; Life; Light; Logic; Microarray Analysis; Molecular Profiling; Mouse-ear Cress; Mustard; Mutation; Nature; Nuclear; Organism; Pathway interactions; Plant Roots; Plants; Process; Proteins; Regulation; Repression; Role; Somatic Mutation; Specific qualifier value; Staging; Structure; Testing; Transcription Repressor/Corepressor; Transgenic Organisms; Yeasts; cancer type; cell type; cold temperature; gene repression; mutant; research study; zygote

DESCRIPTION (provided by applicant): In both animals and plants, the formation of a polar axis is one of the first steps during embryogenesis. Cell fate must then be specified and maintained along this axis in order for proper development to occur. In animals, inherited and somatic mutations in the genes that regulate this process can lead to many types of cancers. Therefore it is important to identify and understand the mechanisms by which these proteins act. We have identified a mutation in the Arabidopsis TOPLESS gene (tpl-1) that cause the transformation of the apical half of the embryo (the shoot) into a second basal half (the root). The apical half of early tpl- 1 embryos express shoot fate genes, but these are lost later in embryogenesis and replaced by the expression of root fate genes. The TPL protein shows structural similarity to known co-repressors, and tpl-1 can be suppressed by mutations in the putative co-activator HAG1, a GCN5-1ike protein. This has lead us to a hypothesis wherein TPL acts as a transcriptional co-repressor, whose role is to fix the identity of the shoot by repressing genes required for root formation in the apical half of the embryo. We propose to test this hypothesis and use TPL and HAG to identify other key regulators of embryonic polarity. In AIM 1, we will test if TPL can act as a transcriptional repressor using both yeast and in planta transcriptional repression assays and determine if the tpl-1 mutation affects the ability of TPL to repress transcription. We will also fuse TPL to known activation and repression domains and analyze the phenotypic consequences in transgenic Arabidopsis. In AIM2, we will use microarray analysis to compare wild-type, tpl-1 and tpl-1;hag1 mutant embryos to identify the common downstream genes of TPL and HAG1. We will use inducible forms of TPL, tpl-1 and HAG1 to place these downstream genes into a temporal context. In AIM3 we will perform an enhancer, a suppressor, and a modular misexpression screen on tpl-1 to identify other genes in the TPL/HAG 1 pathway. These experiments will shed light on one of the mechanisms by which plants specify and maintain cell types during embryogenesis. It will allow us to compare the proteins and logic used in plants to those used in cognate processes in animal development, leading to a better understanding of both.

描述（由申请人提供）：在动物和植物中，极轴的形成是胚胎发生过程中的第一步。然后，必须沿着该轴指定并维持细胞命运，以便发生适当的发育。在动物中，调节这一过程的基因的遗传突变和体细胞突变可能导致多种类型的癌症。因此，识别和理解这些蛋白质的作用机制非常重要。我们在拟南芥 TOPLESS 基因 (tpl-1) 中发现了一个突变，该突变导致胚胎的顶端部分（芽）转变为第二个基部部分（根）。早期 tpl-1 胚胎的顶端一半表达茎命运基因，但这些基因在胚胎发生后期丢失并被根命运基因的表达所取代。 TPL 蛋白与已知的共阻遏物显示出结构相似性，并且 tpl-1 可以通过假定的共激活物 HAG1（一种 GCN5-1 样蛋白）中的突变来抑制。这使我们得出一个假设，其中 TPL 充当转录辅助抑制子，其作用是通过抑制胚胎顶端形成根所需的基因来固定芽的身份。我们建议检验这一假设，并使用 TPL 和 HAG 来识别胚胎极性的其他关键调节因子。在 AIM 1 中，我们将使用酵母和植物转录抑制测定来测试 TPL 是否可以充当转录抑制子，并确定 tpl-1 突变是否影响 TPL 抑制转录的能力。我们还将将 TPL 与已知的激活和抑制域融合，并分析转基因拟南芥中的表型后果。在AIM2中，我们将使用微阵列分析来比较野生型、tpl-1和tpl-1;hag1突变体胚胎，以鉴定TPL和HAG1的共同下游基因。我们将使用 TPL、tpl-1 和 HAG1 的诱导形式将这些下游基因置于时间背景中。在 AIM3 中，我们将对 tpl-1 执行增强子、抑制子和模块化错误表达筛选，以识别 TPL/HAG 1 途径中的其他基因。这些实验将揭示植物在胚胎发生过程中指定和维持细胞类型的机制之一。它将使我们能够将植物中使用的蛋白质和逻辑与动物发育中同源过程中使用的蛋白质和逻辑进行比较，从而更好地理解两者。