Molecular mechanisms of cell fate specification

细胞命运规范的分子机制

基本信息

批准号：
8344133
负责人：
LYNNE M ANGERER
金额：
$ 126.61万
依托单位：
NATIONAL INSTITUTE OF DENTAL & CRANIOFACIAL RESEARCH
依托单位国家：
美国
项目类别：
财政年份：
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/8344133
关键词：
Adult Affect Anterior Anus Binding Biological Models Blastopores Cell Lineage Cells Collaborations Commit Communication Complement Complex Development Developmental Biology Diffuse Dopamine Dopamine D2 Receptor Dopamine Receptor Dorsal Ectoderm Ectoderm Cell Embryo Endoderm Endomesoderm Environment Epidermis Equilibrium Event Evolution Explosion Food Genes Genetic Transcription Goals Growth Individual Larva Ligands Link Lipids Manuscripts Mediating Mesoderm Modeling Molecular Nature Nerve Nervous system structure Neuroectoderm Neurons Nodal Nuclear Export Oral Oral cavity Orthologous Gene Out-Migrations Pathway interactions Pattern Pharyngeal structure Positioning Attribute Preparation Primitive foregut structure Process Production Prosencephalon Proteins Publishing Regulator Genes Regulatory Pathway Reporting Research Role Sea Urchins Side Signal Pathway Signal Transduction Specific qualifier value Staging Starfish Structure Testing Time Tissues To specify Vertebrates Work arm beta catenin cell fate specification delta-catenin density developmental plasticity dopaminergic neuron environmental change fascinate feeding genetic regulatory protein inhibitor/antagonist insight nerve stem cell neural patterning neurodevelopment neurogenesis notch protein novel oral ectoderm pluripotency progenitor programs receptor receptor function relating to nervous system research study response segregation skeletal transcription factor

项目摘要

1) The evolution of nervous system patterning: insights from sea urchin development. Lynne Angerer (15%) in collaboration with Robert D. Burke, Shunsuke Yaguchi and Robert Angerer. We published this review in Development 138:3613-23. It discusses recently elucidated mechanisms that localize and pattern the nervous system of sea urchin embryos. These include the recent findings that there are two overlapping regions of neurogenic potential at the beginning of embryogenesi that are remodeled by separate, yet linked, signals, including Wnt and subsequently Nodal and BMP. These signals act to specify and localize the anterior and ciliary band neural fields. Comparison of the evolution of these patterning signals highlights the extreme conservation of mechanisms underlying the processes that set up neuroectoderm territories in deuterostomes. 2) Control of Wnt signaling in the anterior neuroectoderm. (15%) (Ryan Range and Lynne Angerer) Our objective was to determine how Wnt signaling controls the development of regions that will give rise to neurons (neuroectoderm) versus those that do not. Neuroectoderm forms where Wnt is antagonized and epidermal ectoderm differentiates where Wnt is active. At least three different Wnt pathways, Wnt/β-catenin, Wnt/PCP and Wnt/Ca+2, set up these two types of ectoderm and at least three different regulators of Wnt signaling, Dkk1, sFRP1/5 and Dkk3 are expressed in the anterior neuroectoderm where Wnt signaling is low. Two different Wnt receptors, Frizzled 5/8 and Frizzled 1/2/7, function in at least two of these pathways and they mediate antagonistic activities with respect to ectoderm patterning. Frizzled 5/8 activity converts neuroectoderm except that at the anterior end to epidermis while Frizzled 1/2/7 activity slows down this Frizzled 5/8-dependent function, allowing accumulation of neuroectoderm regulatory proteins. When Frizzled1/2/7 expression is down regulated at the anterior end of the embryo, another Frizzled5/8 inhibitor, Dkk1 is up regulated protecting conversion of neuroectoderm to non-neural ectoderm fates. These studies have revealed a set of unexpected and surprisingly complex interactions among different Wnt pathways that function in early patterning. Manuscript in preparation. 3) Role of individual Wnt ligands in ectoderm patterning. (10%) (Zheng Wei, Ryan Range and Lynne Angerer) Surprisingly we found that Wnt1 activity is required at a relatively late stage to maintain the correct orientation of oral and aboral tissues that form on the ventral and dorsal sides of the embryo. In embryos lacking Wnt1, nodal is ectopically expressed in posterior ventral ectoderm and endoderm and its signaling converts their fates to oral ectoderm. As a consequence the ciliary band position shifts from the ventral to the dorsal side of the blastopore or anus. And the blastopore, which marks the posterior pole of the embryo, is now at the posterior edge of the oral ectoderm near the mouth, an anterior structure, as a result of the exaggerated morphological distortions of the embryo. This work shows that continued interactions between Wnt and Nodal signaling are required to maintain the body plan of the embryo. Manuscript, submitted. 4) De novo neurogenesis in the foregut. (10%) (Zheng Wei, Lynne Angerer) We made the surprising discovery that pharyngeal neurons of sea urchin embryos develop de novo from foregut endoderm through the activity of the transcription factors, Six3 and Nkx3-2. We ruled out migration of ectodermal cells to the pharynx by tracking all presumptive ectoderm cells with the photo-activatable protein, KikGR. Neurons appear in the foregut even when it does not join with ectoderm to form the mouth. We showed that Six3 is expressed transiently in foregut precursors and established that Six3 is required for Nkx3-2, which is required for foregut neural differentiation. These findings reveal that botth endodermal and neural gene regulatory networks operate in foregut cell lineages. This pluripotency may be facilitated by the activity of SoxB1, an ortholog of vertebrate factors shown to maintain a neural precursor state. These results challenge a fundamental concept in developmental biology that nerves develop only from ectoderm. This work was published this year in Proc. Nat. Acad. Sci USA, 108, 9143-9147. 5) De novo neurogenesis in the foregut in sea star embryos. (5%) (Rocio Benabentos and Lynne Angerer) This project was initiated in June, 2011, to determine if de novo pharyngeal neurogenesis also operates in an echinoderm that diverged approximately 500 mya. Neurons are present in the pharynx and experiments tracking their origins and testing whether the same gene regulatory pathway operates in these cells are underway. 6) Mechanisms underlying endomesoderm segregation. (15%) (Adi Sethi, Lynne Angerer) Although, in vertebrate embryos, Wnt/beta-catenin signaling is known to be required for endomesoderm specification and Notch is implicated in controlling the balance between endoderm and mesoderm, how these actually work in the transition from endomesoderm progenitor to stably committed endoderm and mesoderm is not understood. In sea urchin embryos, endomesoderm segregation requires sequential Notch and Wnt/beta-catenin signaling, which restricts endoderm and mesoderm gene regulatory networks operating simultaneously in endomesoderm progenitors, specifically to endoderm and mesoderm lineages. Notch initiates segregation in mesoderm progenitors by inhibiting expression of the transcription factor, Hox11/13b, which drives a key early endoderm regulatory circuit. This circuit subsequently activates transcription of the Wnt/beta-catenin ligand, Wnt1, only in the presumptive endoderm because Notch inactivates the circuit in the mesoderm. The Wnt1-dependent Wnt/beta-catenin circuit reinforces the distinction between endoderm and mesoderm. Finally, Notch signals promote the nuclear export of the beta-catenin binding partner, TCF, thereby completely insulating the mesoderm from Wnt/beta-catenin activity and an endoderm fate. This three-step mechanism generates optimal signaling environments in endoderm and mesoderm and may constitute a mechanism used in many embryos to achieve endomesoderm segregation. Manuscript, in review. 7) Dopaminergic neurons regulate the embryos response to food density (15%) (Diane Adams, Lynne Angerer) Previous work with pharmacological inhibitors of dopamine receptor function suggested that dopamine signaling was involved in the embryos response to food density. We have confirmed this hypothesis by perturbing this pathway at the level of dopamine production, dopamine activity and by eliminating a dopamine D2 receptor. The surprising finding from this work is that the default developmental program, which occurs in the absence of food, supports the growth of long arms. In contrast, when dopamine signaling is stimulated, which occurs at high food densities, the developmental program is suppressed. Thus, the commonly held view that the developmental plasticity involves growth of longer larval arms to optimize food gathering potential is incorrect; instead plasticity relies on a signaling pathway that works in the opposite direction, to inhibit arm growth. Thus, selection for developmental plasticity is not to enhance food gathering potential, but to favor conservation of maternal reserves. Consistent with this hypothesis, we found that embryos with long arms have a significant loss of lipid reserves. Because neurons producing dopamine are positioned near the points of skeletal growth, they are excellent candidates for mediating the skeletal growth response. A manuscript reporting this novel mechanism of developmental plasticity is in final revision in Nature Communications.

1）神经系统模式的演变：海胆开发的见解。 Lynne Angerer（15％）与Robert D. Burke，Shunsuke Yaguchi和Robert Angerer合作。我们在开发中发表了这篇评论138：3613-23。它讨论了最近阐明了将海胆胚胎神经系统定位和模拟的机制。其中包括最近的发现，即在胚胎素内的开头有两个重叠的神经源潜力区域，这些区域被单独但链接的信号重塑，包括Wnt，以及随后的Nodal和BMP。这些信号起作用，以指定和定位前和睫状带神经场。这些图案信号的演变的比较突出了在氘代表中建立神经外科领土的过程的极端保存。 2）控制前神经外胚层中的Wnt信号传导。（15％）（Ryan Range和Lynne Angerer）我们的目标是确定Wnt信号如何控制会导致神经元（神经外胚层）的区域的发展，而不是那些不引起神经元的发展。神经外胚层形式，其中Wnt被拮抗而表皮外胚层在Wnt处于活性的情况下。至少三种不同的Wnt途径，即Wnt/β-catenin，Wnt/PCP和Wnt/Ca+2，建立了这两种类型的外胚层和Wnt信号传导的三种不同调节剂，DKK1，SFRP1/5和DKK3在wnt的前神经ectoderm中表达，其中Wnt信号降低。两种不同的Wnt受体，毛躁5/8，毛躁1/2/7至少在这些途径中起作用，并且相对于外胚层构图，它们介导了拮抗活动。毛躁的5/8活性转化了神经外胚层，除了在表皮前端的毛躁1/2/7活性在毛躁下减慢了这种卷曲的5/8依赖性功能，从而允许神经外固性调节蛋白的积累。当卷曲1/2/7表达在胚胎的前端调节时，另一个毛躁5/8抑制剂会受到调节，以保护神经外胚层转化为非神经外胚层命运。这些研究揭示了在早期构图中起作用的不同WNT途径之间的一系列意外且令人惊讶的复杂相互作用。手稿准备。 3）单个Wnt配体在外胚层图案中的作用。（10％）（Zheng Wei，Ryan Range和Lynne Angerer）令人惊讶地发现，在相对较晚的阶段需要Wnt1活性，以维持在胚胎的腹侧和背侧形成的口腔和原住民组织的正确方向。在缺乏Wnt1的胚胎中，淋巴结在后腹侧外胚层和内胚层中以异位表达，其信号传导将其命运转化为口服外胚层。结果，睫状带的位置从腹侧或肛门的背侧移动。标记胚胎后极的胚孔位于口腔外胚层的后边缘，由于胚胎的夸张形态扭曲，嘴巴附近的口腔外侧边缘是一个前结构。这项工作表明，需要Wnt和Nodal信号之间的持续相互作用以维持胚胎的身体计划。手稿，提交。 4）前库特中的从头神经发生。（10％）（Zheng Wei，Lynne Angerer），我们提出了一个令人惊讶的发现，即海胆胚胎的咽神经元通过转录因子的活性Six3和NKX3-2从前胚层开始从头开始。我们排除了外胚层细胞迁移到咽部的迁移，通过使用光活化蛋白Kikgr跟踪所有假定的外胚层细胞。即使神经元不与外胚层结合以形成口腔，神经元也会出现。我们表明，六3在前面的前体中暂时表达，并确定NKX3-2需要六个3，这是前述神经分化所必需的。这些发现表明，植物性内胚层和神经基因调节网络在前肢细胞谱系中起作用。 SOXB1的活性可能会促进这种多能性，Soxb1的活性是脊椎动物因子的直系同源物，证明维持神经前体状态。这些结果挑战了发育生物学中的基本概念，该概念仅来自外胚层。这项工作今年在Proc。纳特。学院。 SCI USA，108，9143-9147。 5）在海星胚胎中的前肢中的从头神经发生。（5％）（Rocio Benabentos和Lynne Angerer）该项目于2011年6月启动，以确定Novo Novo咽神经发生是否也在大约500个Mya的棘皮动物中运行。神经元存在于咽部中，并且实验跟踪其起源并测试这些细胞中相同的基因调节途径是否正在进行中。 6）内胚层分离的基础机制。 (15%) (Adi Sethi, Lynne Angerer) Although, in vertebrate embryos, Wnt/beta-catenin signaling is known to be required for endomesoderm specification and Notch is implicated in controlling the balance between endoderm and mesoderm, how these actually work in the transition from endomesoderm progenitor to stably committed endoderm and mesoderm is not understood. 在海胆的胚胎中，内粒胚层分离需要顺序的Notch和Wnt/β-catenin信号，这限制了内胚层和中胚层基因调节网络，同时在内胚层祖细胞中，特别是内胚层和中胚层和中胚层。 Notch通过抑制转录因子HOX11/13B的表达来启动中胚层祖细胞的分离，该转录因子驱动了关键的早期内胚层调节回路。该电路随后激活Wnt/beta-catenin配体Wnt1的转录，仅在假定的内胚层中，因为Notch会使中胚层中的电路失活。依赖Wnt1的Wnt/β-catenin电路增强了内胚层和中胚层之间的区别。最后，Notch信号促进了β-catenin结合伙伴TCF的核出口，从而完全使中胚层与Wnt/β-catenin活性和内胚层命运完全绝缘。这种三步机制在内胚层和中胚层中产生最佳信号环境，并且可能构成许多胚胎中用于实现内胚层分离的机制。手稿，在审查中。 7）多巴胺能神经元调节胚胎对食物密度的反应（15％）（黛安·亚当斯，林恩·愤怒者）先前与多巴胺受体功能的药理抑制剂的先前作品表明，多巴胺信号传导参与了胚胎对食品密度的胚胎反应。我们通过在多巴胺产生，多巴胺活性和消除多巴胺D2受体的水平上扰动这一途径来证实这一假设。这项工作中令人惊讶的发现是，在没有食物的情况下发生的默认发展计划支持长臂的成长。相反，当刺激多巴胺信号传导（在高食物密度下发生）时，发育计划就会被抑制。因此，通常认为发育可塑性涉及较长的幼虫臂的生长以优化食物收集潜力的观点是不正确的。相反，可塑性依赖于朝相反方向起作用的信号通路来抑制手臂的生长。因此，选择可塑性不是为了增强食物收集潜力，而是倾向于保存孕产妇储量。与这一假设一致，我们发现具有长臂的胚胎具有明显的脂质储量损失。由于产生多巴胺的神经元位于骨骼生长点附近，因此它们是介导骨骼生长反应的极好候选者。报告这种新颖的发展可塑性机制的手稿是自然通信的最终修订。