Orphan nuclear receptors and mammalian development

孤儿核受体和哺乳动物发育

• 批准号: 8939590
• 负责人: Douglas Forrest
• 金额: $ 61.84万
• 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/8939590
• 关键词: Amacrine Cells; Bipolar Neuron; Brain; Cell Separation; Cells; Color Visions; Cone; Defect; Degenerative Disorder; Detection; Development; Disease; Event; Functional disorder; Gene Expression; Gene Targeting; Generations; Genes; Genetic; Goals; Hormones; Human; Intellectual functioning disability; Interneurons; Investigation; Lead; Ligands; Light; Mammals; Mediating; Modeling; Molecular; Mutation; N-terminal; Nervous system structure; Neurons; Nuclear Orphan Receptor; Nuclear Receptors; Opsin; Organ; Orphan; Pattern; Photoreceptors; Physiological; Play; Population; Predisposition; Procedures; Protein Isoforms; Receptor Gene; Reporting; Retina; Retinal; Retinal Cone; Retinoids; Role; Seizures; Specificity; Synaptic Transmission; System; Testing; Tissues; Variant; Vertebrate Photoreceptors; Vision; cell type; gain of function; ganglion cell; gene function; horizontal cell; mouse model; mutant; neurodevelopment; neuron development; next generation sequencing; novel; receptor; receptor expression; receptor function; research study; retinal progenitor cell; retinal rods; sensory system; transcription factor; transmission process

In mammalian development, the formation of a given tissue and its array of specialized cell types is often guided by a genetic hierarchy involving the successive activation of key developmental control genes. These genes often encode transcription factors that direct key events that prompt an immature, non-specialized cell mass to form a mature, functioning organ. Nuclear receptors are ligand-regulated transcription factors that respond to hormones or other ligands. Orphan receptors are a special group of nuclear receptors that lack known physiological ligands but play critical functions in tissue development. The retinoid-related orphan nuclear receptor b gene (Rorb), is specifically expressed in the brain and retina. It has recently been reported that mutations in the human RORB gene are associated with cases of intellectual disability and seizure susceptibility, thus implicating the RORB gene with an important role in the human nervous system. However, the functions of this gene and how defects in the gene result in disease are incompletely understood. The goal of this project is to elucidate the tissue-specific functions of the Rorb gene in development and to indicate how the dysfunction of the gene causes disease. The study of the Rorb gene offers the opportunity to elucidate novel functions for an orphan nuclear receptor in a defined neurodevelopmental system. Progress: 1. The role of Rorb in neurodevelopment. We have investigated in detail the expression pattern of the Rorb gene in retina and continue to extend these studies in other sensory systems and the brain. The pattern is suggestive of functions in the divergent cell fate choice between rod and cone photoreceptors and in the early steps in the generation of horizontal and amacrine interneurons. We continue our study of the role of the Rorb gene in directing the differentiation of cone and rod photoreceptors. In dichromatic mammals, cones express opsin photopigments that are sensitive to short (S, blue) or medium-longer (M, green) wavelengths of light whereas rods mediate detection of dim light. Our investigations have also established that Rorb is critical for the generation of two classes of retinal interneurons: horizontal cells that modify synaptic transmission between photoreceptors and bipolar neurons, and amacrine cells that modify transmission between bipolar neurons and ganglion cells. 2. The Rorb gene is remarkable for the variety of different functions it controls in retinal development. To investigate how a single gene can control distinct neurodevelopmental functions, we pursue ongoing studies to determine the roles of two N-terminal isoform products encoded by the Rorb gene. Targeted deletions of these RORb1 and RORb2 isoforms have been generated in mammalian models and the phenotypic consequences are being determined to indicate how this developmental control gene is capable of regulating several different cell-specific functions. Our studies investigate how these differentially expressed isoforms provide additional level of versatility in directing cell-specific functions in neuronal development. We pursue additional studies to investigate the key downstream target genes that underlie the functions of these orphan receptor isoforms, using a range of tissue and cell-isolation procedures and next generation sequencing approaches.

在哺乳动物的发育中，给定组织的形成及其专门细胞类型的数组通常以涉及关键发育控制基因连续激活的遗传层次结构进行指导。这些基因通常编码转录因子，这些转录因子引导关键事件，这些事件促使未成熟，非特异性细胞质量形成成熟，功能性的器官。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组织发育中起关键功能的特殊核受体。与性类维生素相关的孤儿核受体B基因（RORB）在大脑和视网膜中特别表达。 最近据报道，人类RORB基因的突变与智障和癫痫敏感性的病例有关，因此暗示了Rorb基因在人类神经系统中具有重要作用。然而，该基因的功能以及基因中的缺陷如何导致疾病中的缺陷。 该项目的目的是阐明RORB基因在发育中的组织特异性功能，并指出基因功能障碍是如何引起疾病的。 RORB基因的研究为阐明定义神经发育系统中孤儿核受体的新功能提供了机会。进步： 1。罗布在神经发育中的作用。我们已经详细研究了视网膜中RORB基因的表达模式，并继续在其他感觉系统和大脑中扩展这些研究。 该模式暗示了在杆和锥形感受器之间的不同细胞命运选择中的功能以及在水平和无氨基氨酸中间神经元生成的早期步骤中。 我们继续研究RORB基因在指导锥和杆感光体分化中的作用。 在二分性哺乳动物中，锥体表达对短的（S，蓝色）或中长（m，绿色）波长敏感的光成型，而杆介导了昏暗的光的检测。 我们的研究还确定，RORB对于产生两类的视网膜中间神经元至关重要：水平细胞可修饰光感受器和双极神经元之间的突触传播，以及修改双极神经元和神经节细胞之间传播的无分泌细胞。 2。RORB基因对于视网膜发育中控制的各种功能而言是显着的。 为了研究单个基因如何控制不同的神经发育功能，我们进行了持续的研究，以确定RORB基因编码的两个N末端同工型产物的作用。 这些RORB1和RORB2同工型的有针对性缺失已在哺乳动物模型中产生，并且正在确定表型后果，以指示该发育控制基因如何能够调节几种不同的细胞特异性功能。 我们的研究研究了这些差异表达的同工型如何在指导细胞特异性功能中在神经元发育中提供更多的多功能性。 我们进行了其他研究，以研究这些孤儿受体同工型功能的主要下游靶基因，使用一系列组织和细胞隔离程序以及下一代测序方法。