Orphan nuclear receptors and mammalian development

孤儿核受体和哺乳动物发育

基本信息

批准号：
9148818
负责人：
Douglas Forrest
金额：
$ 61.41万
依托单位：
NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
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/9148818
关键词：
Amacrine Cells Bipolar Neuron Brain Cell Separation Cells Color Visions Cone Defect Detection Development Disease Functional disorder Gene Targeting Generations Genes Genetic Goals Hormones Human Intellectual functioning disability Interneurons Lead Ligands Light Mammals Mediating Modeling Molecular Mus Mutation N-terminal Nervous system structure Neurodegenerative Disorders Neurons Nuclear Orphan Receptor Nuclear Receptors Opsin Organ Orphan Pattern Photoreceptors Physiological Play Population Predisposition Procedures Protein Isoforms Reporting Retina Retinal Retinal Cone Retinoids Role Seizures Sensory Specificity Stem cells Synaptic Transmission System Testing Tissues Undifferentiated Variant Vertebrate Photoreceptors Vision cell type differential expression gain of function ganglion cell gene function horizontal cell human disease 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

项目摘要

In mammalian development, the formation of a tissue and its 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 prompt an immature, non-specialized cell mass to become a mature, functioning organ composed of appropriate proportions of specific cell types. 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 prominently 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 the RORB 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 in a mammalian model species 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 the nervous system and continue to extend these studies in sensory systems and the brain. In the retina, undifferentiated progenitor cells divide and generate a range of specific cell types including photoreceptors, different types of interneurons and ganglion cells. The expression pattern of the Rorb gene suggests 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 have studied 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 studies have established that Rorb also directs the generation of two classes of retinal interneurons: (i) horizontal cells that modify synaptic transmission between photoreceptors and bipolar neurons, and (ii) 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 are pursuing studies to determine the roles of two N-terminal isoform products encoded by the Rorb gene. These Rorb1 and Rorb2 isoforms are differentially expressed in different tissues and cell types of the nervous system. The consequences of targeted deletions of the RORb1 and RORb2 isoforms in the mouse, a mammalian model species,are being determined to indicate how this developmental control gene is capable of regulating 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 are pursuing further studies to investigate critical 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，组织的形成及其专门的细胞类型通常以涉及关键发育控制基因的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，这些转录因子促使未成熟，非特殊的细胞量成为由适当比例的特定细胞类型组成的成熟，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。在大脑和视网膜中显着表达与类视黄素相关的孤儿核受体B基因（RORB）。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。但是，RORB基因的功能以及基因中的缺陷如何导致疾病。该项目的目的是阐明RORB基因在哺乳动物模型物种中发育中的组织特异性功能，并指出该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神经系统中RORB基因的表达模式，并继续在感觉系统和大脑中扩展这些研究。在视网膜中，未分化的祖细胞分裂并产生一系列特定细胞类型，包括感光体，不同类型的中间神经元和神经节细胞。 RORB基因的表达模式表明，在杆和锥形感受器之间的不同细胞命运选择中以及水平和无链氨酸中间神经元的早期步骤中的功能。我们研究了RORB基因在指导锥和杆感光体的分化中的作用。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。我们的研究已经确定，RORB还指导两类的视网膜中间神经元的产生：（i）修饰感光体和双极神经元之间突触传播的水平细胞，以及（ii）修饰双极神经元和神经节细胞之间传播的无链氨基细胞。 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，我们正在进行研究以确定RORB基因编码的两个N末端同工型产物的作用。这些RORB1和RORB2同工型在神经系统的不同组织和细胞类型中差异表达。正在确定哺乳动物模型物种中RORB1和RORB2同工型的靶向缺失的后果，以表明该发育控制基因如何能够调节不同细胞特异性功能。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。我们正在进行进一步的研究，以研究这些孤儿受体同工型功能的关键下游靶基因，使用一系列组织和细胞隔离程序以及下一代测序方法。