Orphan nuclear receptors and mammalian development

孤儿核受体和哺乳动物发育

• 批准号: 10008662
• 负责人: Douglas Forrest
• 金额: $ 74.94万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 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/10008662
• 关键词: Address; Amacrine Cells; Brain; Brain region; Cell Differentiation process; Cell Lineage; Cell Separation; Cell physiology; Cells; Clinic; Collaborations; Collection; Cone; Defect; Development; Disease; Epilepsy; Event; Eye Movements; Functional disorder; Gene Activation; Gene Expression; Gene Expression Regulation; Generations; Genes; Genetic Models; Genetic Transcription; Genome; Goals; Head Movements; Hormones; Human; Impairment; Inner Nuclear Layer; Intellectual functioning disability; Interneurons; Investigation; Lead; Ligands; Light; Mediating; Modeling; Molecular Analysis; Morphology; Mus; Mutation; N-terminal; Nervous system structure; Neuraxis; Neurodegenerative Disorders; Neuronal Differentiation; Neurons; Nuclear Orphan Receptor; Nuclear Receptors; Optic Nerve; Organ; Orphan; Other Genetics; Pathway interactions; Pattern; Photoreceptors; Physiological; Play; Predisposition; Procedures; Protein Isoforms; Receptor Gene; Reporting; Retina; Retinal; Retinal Cone; Retinoids; Role; Seizures; Sensory; Spinal Cord; Stem cells; Subgroup; System; Testing; Tissues; Transcriptional Regulation; Undifferentiated; Universities; Vision; Visual Pathways; Visual system structure; cell type; developmental disease; differential expression; experimental study; gain of function; ganglion cell; gene function; gene product; genetic approach; horizontal cell; mouse model; neurodevelopment; next generation sequencing; novel; receptor; receptor binding; retinal progenitor cell; retinal rods; sensory input; sensory system; superior colliculus Corpora quadrigemina; transcription factor; transmission process; visual information; visual process

In mammalian development, the formation of a tissue and its specialized cell types is often guided by the activation of key developmental control genes. Such genes often encode transcription factors that prompt undifferentiated progenitor cells to form a mature, functioning organ composed of a variety of cell types. Nuclear receptors are ligand-regulated transcription factors that respond to hormones or other ligands. Orphan receptors are a sub-group of nuclear receptors that lack known physiological ligands but play a critical role in development and cellular differentiation. The retinoid-related orphan nuclear receptor b gene (Rorb), is expressed in the retina, spinal cord, certain brain regions and a few other tissues. It has been reported that mutations in the human RORB gene are associated with intellectual disability, epilepsy and other impairments, thus implicating this gene with an important role in the human nervous system. However, the functions of this orphan receptor gene and how defects in the gene result in disease are poorly understood. This project aims to elucidate the tissue-specific functions of the Rorb gene in development in mammalian models and to reveal how dysfunction of the gene causes disease. This study aims to reveal novel functions for an orphan receptor in defined developmental systems. Our studies address: 1. Function of the Rorb gene in neurodevelopment. We have investigated the expression and function of the Rorb gene in the central nervous system and sensory systems using mouse genetic models. In the retina, undifferentiated progenitor cells generate a range of cell types including photoreceptors, interneurons and ganglion cells that relay visual information to the brain. The expression pattern of the Rorb gene suggests it has key functions in the determination of specific retinal cell lineages, including rod and cone photoreceptors as well as horizontal and amacrine interneurons. We have established a key role for Rorb in the differentiation of rods, the photoreceptors that mediate vision at night or in dim light conditions. The Rorb gene is essential for the induction of a key rod-determining gene, Nrl. In the absence of Rorb, there is a nearly complete loss of rods and an excess of primitive cone-like cells, consistent with the Rorb acting in the same pathway as the Nrl gene. 2. The Rorb gene is remarkable for the variety of functions it controls in retinal development. To investigate how this gene controls diverse functions, we have determined the roles of two N-terminal products encoded by the Rorb gene. These RORb1 and RORb2 receptor isoforms are differentially expressed in the nervous system and in certain other tissues. Targeted deletions of RORb1 and RORb2 indicate that each isoform controls the differentiation of distinct cell types. We established that RORb1 is critical for the generation of two classes of retinal interneurons, horizontal cells and amacrine cells, neuronal types that process visual information as it is relayed from the photoreceptor layer through the inner nuclear layer of the retina to the the optic nerve. 3. The Rorb gene is also a valuable marker for cell types in other tissues, and in brain regions, including the superior colliculus, a component of the visual pathway that receives different sensory inputs and which influences head and eye movements. Collaborative studies with Dr. In-Jung Kim (Yale University), showed that the Rorb1 isoform marks a layer of neurons in the superficial region of the superior colliculus, which has been useful in defining these neuronal sub-types. Further collaboration with Dr David Monroe (Mayo Clinic) has revealed a role for Rorb in osteoprotection, suggesting a novel role for this gene in additional tissues outside the nervous system. We are building on these findings to pursue investigation of the downstream target genes that presumably underlie the transcriptional functions of this orphan receptor in cell differentiation and development. We address these aims using a range of genetic approaches, cell-isolation procedures and next generation sequencing analyses.

在哺乳动物的发育中，组织及其专门细胞类型的形成通常以关键发育控制基因的激活为指导。这些基因通常编码转录因子，这些转录因子促使未分化的祖细胞形成由多种细胞类型组成的成熟，功能的器官。核受体是配体调节的转录因子，对激素或其他配体有反应。孤儿受体是缺乏已知生理配体但在发育和细胞分化中起关键作用的核受体的亚组。在视网膜，脊髓，某些大脑区域和其他一些组织中表达与视网膜类动物相关的孤儿核受体B基因（RORB）。据报道，人类RORB基因中的突变与智障，癫痫和其他障碍有关，因此在人类神经系统中牵涉到具有重要作用的基因。但是，该孤儿受体基因的功能以及基因中的缺陷如何导致疾病的理解。该项目旨在阐明RORB基因在哺乳动物模型中发育中的组织特异性功能，并揭示基因功能障碍如何引起疾病。这项研究旨在揭示定义的发育系统中孤儿受体的新功能。我们的研究指出： 1。rorb基因在神经发育中的功能。我们使用小鼠遗传模型研究了RORB基因在中枢神经系统和感觉系统中的表达和功能。在视网膜中，未分化的祖细胞会产生一系列细胞类型，包括感光体，中间神经元和神经节细胞，这些细胞将视觉信息传递到大脑。 RORB基因的表达模式表明，它在确定特定的视网膜细胞谱系（包括杆和锥形感受器以及水平和小氨酰核中神经元）中具有关键功能。我们已经确定了RORB在杆的分化中的关键作用，杆的分化，棒的夜晚或昏暗的光照条件下介导视觉的光感受器。 RORB基因对于诱导关键杆差基因NRL至关重要。在没有RORB的情况下，杆几乎完全丢失，原始锥状细胞过量的损失与与NRL基因相同的途径的RORB一致。 2。RORB基因对于它在视网膜发育中控制的各种功能而引人注目。为了研究该基因如何控制各种功能，我们确定了由RORB基因编码的两个N末端产物的作用。这些RORB1和RORB2受体同工型在神经系统和某些其他组织中差异表达。 RORB1和RORB2的靶向缺失表明，每个同工型都控制着不同细胞类型的分化。我们确定RORB1对于产生两类的视网膜中间神经元，水平细胞和无长熟细胞，神经元类型至关重要，这些神经元类型会通过视网膜的内部核层从光感受器层中传播视觉信息，从而处理视神经。 3。RORB基因也是其他组织中细胞类型的有价值的标记，在包括上丘中的大脑区域，视觉途径的一个组成部分，它接收不同的感觉输入并影响头部和眼睛运动。与耶鲁大学In-Jung Kim博士的合作研究表明，RORB1同工型标记了上丘丘的表面区域中的一层神经元，该神经元在定义这些神经元亚类型方面很有用。 与David Monroe博士（Mayo Clinic）的进一步合作揭示了Rorb在破骨保护中的作用，这表明该基因在神经系统以外的其他组织中起了新作用。 我们正在基于这些发现，以调查下游靶基因，这些基因可能是该孤儿受体在细胞分化和发育中的转录功能的基础。 我们使用一系列遗传方法，细胞隔离程序和下一代测序分析来解决这些目标。