Molecular mechanisms of cell fate specification

细胞命运规范的分子机制

• 批准号: 7967096
• 负责人: LYNNE M ANGERER
• 金额: $ 109.08万
• 依托单位: NATIONAL INSTITUTE OF DENTAL & CRANIOFACIAL RESEARCH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7967096
• 关键词: Agonist; Animals; Bioinformatics; Biological Assay; Biological Models; Biology; Cells; Cilia; Control Animal; Development; Developmental Biology; Developmental Gene; Dopamine; Dopamine Antagonists; Dopamine D2 Receptor; Eating; Ecology; Ectoderm; Embryo; Embryonic Development; Endoderm; Endomesoderm; Event; Evolution; Food; Forebrain Development; Gene Structure; Genes; Genome; Germ Layers; Growth; Indium; Intramural Research Program; Investigation; Larva; Length; Mediating; Mesoderm; Mesoderm Cell; Microscope; Modeling; Molecular; Morphology; National Institute of Dental and Craniofacial Research; Nerve; Nervous system structure; Neurons; Operative Surgical Procedures; Oral; Orthologous Gene; Output; Pathway interactions; Pattern; Physiology; Play; Positioning Attribute; Process; Production; Prosencephalon; Publishing; Refractory; Regulator Genes; Relative (related person); Repression; Research; Rest; Role; Sea Urchins; Signal Pathway; Signal Transduction; Specific qualifier value; Staging; Tissues; Transforming Growth Factor beta; Translations; Tyrosine 3-Monooxygenase; Upper arm; Vertebrates; Work; animal tissue; base; blastocyst; cell fate specification; cell type; density; dopaminergic neuron; gastrulation; gene function; genetic regulatory protein; high risk; insight; interest; loss of function; nervous system development; neurogenesis; notch protein; programs; relating to nervous system; research study; response; retinal rods; segregation; skeletal

The major questions we focus on are: 1) What are the upstream regulatory components that specify the animal pole domain (APD) of the sea urchin embryo, which contains nerves and cells bearing long, immotile cilia? 2) What are the signals transmitted during early cleavage and blastula stages that are required for endomesoderm specification and timely gastrulation? 3) What is the molecular basis for the embryo's ability to change its morphology to adapt to changing food concentrations? In each case, we assay the expression of all predicted genes in the genome in order to gain a complete understanding of the gene regulatory networks that underlie these processes. Six3 is necessary and sufficient for APD specification (50%) (Zheng Wei, Ryan Range, Lynne Angerer) During the last several years, using bioinformatics and molecular screens, we identified many genes encoding regulatory proteins expressed specifically in the primary neurogenic domain of the sea urchin embryo. Two of the earliest, FoxQ2 and Six3, control early decisions in ectodermal patterning. Experiments conducted during 2008 showed that Six3 is necessary and sufficient for all known features of APD development. This includes all neurons formed during embryogenesis and the large majority of APD-specific regulatory proteins previously identified, including FoxQ2. We identified the full regulatory repertoire of genes that depend on Six3, and discovered that this factor can also suppress canonical Wnt and TGF-beta signals that pattern the rest of the embryo. Our work revealed that the function of Six3 in the sea urchin embryo APD shares some features with Six3 in the vertebrate forebrain. Our studies have identified many additional regulatory genes that are Six3-dependent and expressed in the APD. It is therefore of interest to determine whether the vertebrate orthologs of these genes function in vertebrate forebrain development. This work has been published by Wei et al., Development 136, 1179-1189 (2009). FoxQ2 not only can suppress TGF-beta signaling in the APD(Yaguchi et al., Developmental Cell 14, 97-107, 2008), but it also required for controlling Wnt signaling in this territory. Microarray screens show that it is required for the expression of nearly 500 genes including a subset of the genes encoding early APD regulatory proteins and for specialized cilia specifically in the APD. Further, FoxQ2 is required for production of regulators of Wnt signaling. When these regulators are either eliminated or over expressed, the position of the boundary of the APD within the ectoderm is altered. These results reinforce the model that mutual antagonism between the outputs of the APD GRN and Wnt signaling regulates APD development within the early ectoderm of the sea urchin embryo. Activation of the APD GRN depends upon maternal positive regulatory activities. One of these is SoxB1. When SoxB1 is eliminated, differentiation of nerves within the APD is blocked and expression of the key upstream components of the APD GRN, Six3, FoxQ2 and Hbn (homeobrain) are reduced in the blastula-stage embryo. SoxB1 also plays a key role in activating the oral and aboral ectodermal developmental GRNs as well as in suppressing canonical Wnt signaling. Determining how the relative contributions of SoxB1 to ectodermal patterning are controlled will be critical for understanding the initial events that specify cell fates within the ectoderm. ActivinB/ALK4-5-7 and Delta/Notch are early signals that induce specification of endomesoderm and endoderm (25%)(Adi Sethi, Radhika Wikramanayake, Lynne Angerer) Previous experiments showed that both ectopic and normal endomesoderm induction requires ActivinB and that this signaling factor executes all of the endomesoderm inducing functions of the previously unknown, but long-sought, early micromere signal. This work (Sethi, AJ, Angerer, RC, Angerer, LM (PLOS Biology 7(2): ee1000029, 2009) is the first to connect ActivinB signaling to specific components of an endomesoderm gene regulatory (GRN) network, the largest and best developed in any embryo, and it has led to new insights into its operation. Experiments in which Delta/Notch signaling is blocked reveal new functions for this pathway in separating two primary germ layers, the endoderm and mesoderm, within the endomesodermal field. Micromere Delta signals not only activate gcm in overlying macromere progeny, but also repress several critical genes required for early endoderm specification. Recent results suggest that a key element in the specification of presumptive mesodermal cells is the ability of Notch signals to down regulate the canonical Wnt signaling pathway. Dopaminergic neurons regulate the embryo's response to food density (25%) (Diane Adams, Lynne Angerer) A new line of investigation aims to understand the molecular pathways by which larvae sense and respond to food concentration by adjusting arm length to maximize food intake. It is a high-risk project that bridges larval developmental biology, larval physiology and the ecology of larval dispersal. Diane has found that dopamine D2receptor activity regulates changes in the post-oral skeletal rod length in response to food density. She has identified cells expressing dopamine and tyrosine hydroxylase in the post-oral arms where the response to food density occurs. Experiments are underway to identify which D2 receptor mediates this response. To determine other components of the food sensing pathway, she is using microarrays to assay the whole genome reponse to food concentration as well as to dopamine antagonists and agonists.

我们关注的主要问题是：1）什么是上游调控组件，指定动物极域（APD）的海胆胚胎，其中包含神经和细胞轴承长，不动的纤毛？2)在早期卵裂和囊胚阶段，内中胚层特化和原肠胚形成所需的信号是什么？ 3)胚胎改变其形态以适应不断变化的食物浓度的能力的分子基础是什么？ 在每种情况下，我们分析基因组中所有预测基因的表达，以获得对这些过程背后的基因调控网络的完整理解。 Six 3是APD规范（50%）的必要和充分条件（Zheng Wei，Ryan Range，Lynne Angerer） 在过去的几年中，利用生物信息学和分子筛选，我们确定了许多基因编码的调节蛋白表达的海胆胚胎的主要神经原结构域。 最早的两个，FoxQ 2和Six 3，控制外胚层模式的早期决定。 在2008年进行的实验表明，Six 3是必要的和足够的APD发展的所有已知功能。 这包括胚胎发育过程中形成的所有神经元和以前鉴定的绝大多数APD特异性调节蛋白，包括FoxQ 2。我们确定了依赖Six 3的基因的全部调控库，并发现该因子还可以抑制典型的Wnt和TGF-β信号，这些信号对胚胎的其余部分起作用。我们的工作揭示了Six 3在海胆胚胎APD中的功能与Six 3在脊椎动物前脑中的功能有一些共同之处。 我们的研究已经确定了许多其他的调节基因，是Six 3依赖性和APD中表达。 因此，确定这些基因的脊椎动物直系同源物是否在脊椎动物前脑发育中起作用是有意义的。 这项工作已由Wei等人发表，发展136，1179-1189（2009）。 FoxQ 2不仅可以抑制APD中的TGF-β信号传导（Yaguchi et al.，Developmental Cell 14，97-107，2008），但它也需要控制该区域中的Wnt信号传导。微阵列筛选显示，它是近500个基因的表达所必需的，包括编码早期APD调节蛋白的基因的子集和APD中特异性的纤毛。此外，FoxQ 2是产生Wnt信号传导调节剂所必需的。 当这些调节因子被消除或过度表达时，APD在外胚层内的边界位置发生改变。这些结果加强了模型，APD GRN和Wnt信号的输出之间的相互拮抗作用调节APD的海胆胚胎的早期外胚层内的发展。 APD GRN的激活依赖于母体的正调控活动。 其中之一是SoxB 1。 当SoxB 1被消除时，APD内神经的分化被阻断，并且在囊胚期胚胎中APD GRN、Six 3、FoxQ 2和Hbn（同源胚蛋白）的关键上游组分的表达减少。 SoxB 1还在激活口腔和反口腔外胚层发育GRNs以及抑制经典Wnt信号传导中起关键作用。 确定如何控制SoxB 1对外胚层模式的相对贡献对于理解指定外胚层内细胞命运的初始事件至关重要。 激活素B/ALK 4 -5-7和Delta/Notch是诱导内中胚层和内胚层特化的早期信号（25%）（Adi Sethi，Radhika Wikramanayake，Lynne Angerer） 先前的实验表明，异位和正常的内中胚层诱导需要激活素B，并且该信号传导因子执行先前未知但长期寻求的早期微小信号的所有内中胚层诱导功能。 这项工作（Sethi，AJ，Angerer，RC，Angerer，LM（PLOS Biology 7（2）：ee 1000029，2009）是第一个将激活素B信号传导与内中胚层基因调控（GRN）网络的特定组分连接起来的工作，该网络是任何胚胎中最大和最好的，并且它导致了对其操作的新见解。 Delta/Notch信号传导被阻断的实验揭示了该途径在内中胚层领域内分离两个初级胚层（内胚层和中胚层）的新功能。 微单体δ信号不仅激活覆盖大单体后代的gcm，而且抑制早期内胚层特化所需的几个关键基因。最近的结果表明，在推定的中胚层细胞的规格的一个关键要素是Notch信号下调经典Wnt信号通路的能力。 多巴胺能神经元调节胚胎对食物密度的反应（25%）（黛安亚当斯，林恩安格雷） 一项新的研究旨在了解幼虫通过调节臂长来最大限度地摄入食物来感知和响应食物浓度的分子途径。 这是一个高风险项目，它将幼虫发育生物学、幼虫生理学和幼虫扩散生态学联系起来。戴安发现多巴胺D2受体活性调节口腔后骨骼杆长度的变化，以响应食物密度。 她已经确定了表达多巴胺和酪氨酸羟化酶的细胞，在对食物密度的反应发生的口后手臂。实验正在进行中，以确定哪种D2受体介导这种反应。 为了确定食物感应途径的其他成分，她正在使用微阵列来分析整个基因组对食物浓度以及多巴胺拮抗剂和激动剂的反应。