A newly discovered feed-forward mechanism controls photoreceptor fate

新发现的前馈机制控制光感受器的命运

基本信息

批准号：
9042370
负责人：
James G. Patton
金额：
$ 43.77万
依托单位：
VANDERBILT UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-04-01 至 2018-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9042370
关键词：
Aging Animal Model Aqueous Humor Biological Models Blindness Boxing Cell Count Cell Differentiation process Cells Cessation of life Chimeric Proteins Cone Development Disease Dose Embryo Event Eye Future Gene Expression Genes Genetic Genetic Transcription Growth Health Image Imaging Techniques Knowledge Laboratories Life Ligase Macular degeneration Modeling Molecular Mutation Nuclear Hormone Receptors Pathway interactions Patients Photoreceptors Pineal gland Post-Translational Protein Processing Production Proteins Replacement Therapy Research Personnel Retina Retinal Retinal Cone Retinal Degeneration Retinal Diseases Retinitis Pigmentosa Small Ubiquitin-Related Modifier Proteins Stem cells Syndrome System Testing Time Transgenes Transgenic Organisms Translations Transplantation Vertebrate Photoreceptors Vision Zebrafish disease-causing mutation dosage feeding in vivo inherited retinal degeneration insight knock-down lens mutant novel photoreceptor degeneration precursor cell premature programs protein activation restoration retinal progenitor cell retinal rods stem cell therapy success time use tool transcription factor zebrafish development

项目摘要

DESCRIPTION (provided by applicant): Retinal degeneration is a devastating affliction that leads to irreversible loss of vision, resulting from the progressive death of rod and cone photoreceptor cells in the outermost layer of the retina. One of the most promising avenues for replacing photoreceptors following degeneration is the introduction of photoreceptor precursor cells into the retina, which can differentiate into rods and cones. However, in trials of precursor transplant therapy, too many rods and not enough cones are produced. The result of these trials reveals a major hurdle for restoration of vision using stem-cell therapies, and highlights a criticl gap in our knowledge of photoreceptor formation: We do not know the mechanism that switches precursors from production of cone photoreceptors, which arise first, to production rod photoreceptors, which arise second. In order to understand how the number of cone versus rod photoreceptors is regulated, we have established a simple but powerful tool to study photoreceptor development, the zebrafish pineal organ, which shares a very close evolutionary relationship with the eyes. Just as in the retina, the zebrafish pineal contain fully developed rod and cone photoreceptors; in addition, the pineal photoreceptors are molecularly quite similar to those in the retina. A major advantage of the zebrafish pineal for studying photoreceptor development is its simplicity, which allows imaging of the live or fixed pineal organ easily in whole mount embryos without sectioning since there is no interference from the lens, aqueous humor, or overlying retinal layers. Recent studies from our laboratory indicate a novel and unexpected mechanism, called an incoherent feed-forward system, which controls the number of cone and rod cells produced by photoreceptor precursors. We propose that in early photoreceptor precursors, which give rise to cone cells, time-limited expression of the transcription factor Tbx2b expression drives the expression of cone-specific genes and also initiates expression of the cone-gene repressor Nr2e3. Nr2e3 protein continues to accumulate until it reaches a threshold concentration that shuts off cone gene expression and allows rods to form instead. In order to test the implications of our feed-forward hypothesis for photoreceptor formation, we will take advantage of the genetic tools that we and others have generated in zebrafish. Then we will leverage our knowledge to test the effects of a disease-causing mutation in Nr2e3 on feed-forward control. Our studies will illuminate the molecular control of cone versus rod production, which will provide invaluable information for laboratories developing retinal replacement therapies as well as insight into the ontogeny of inherited retinal degeneration disorders.

描述（由申请人提供）：视网膜变性是一种毁灭性的苦难，导致视力丧失，这是由于杆和锥形光感受器细胞在视网膜最外层的渐进性死亡所致。变性后最有前途的途径之一是将光感受器前体细胞引入视网膜，该细胞可以区分杆和锥体。但是，在前体试验中移植疗法，太多的棒和不足的锥体。这些试验的结果揭示了使用干细胞疗法恢复视力的主要障碍，并突出了我们对感光体形成的知识中的批评差距：我们不知道从锥形光感受器中转换前体的机制，该机制首先从产生的锥形光感受器转变为生产杆光感受器，第二位。为了了解如何调节锥体与杆光感受器的数量，我们建立了一种简单但功能强大的工具来研究光感受器的发育，斑马鱼松果体器官，与眼睛具有非常紧密的进化关系。就像在视网膜中一样，斑马鱼松果体包含完全发育的杆和锥形感受器；另外，松果体感受器与视网膜中的光感受器非常相似。斑马鱼松果体研究光感受器发育的主要优点是它的简单性，它可以在整个固定胚胎中轻松地成像活的或固定的松果体，而无需切片，因为透镜，水性幽默没有干扰，或者是视网膜上层。我们实验室的最新研究表明，一种新颖而意外的机制，称为不一致的进料系统，该系统控制着光感受器前体产生的锥形和棒细胞的数量。我们提出，在产生锥细胞的早期感受器前体中，转录因子TBX2B表达的时间限制表达驱动锥体特异性基因的表达，并启动锥形基因抑制剂NR2E3的表达。 NR2E3蛋白继续积聚，直到达到关闭锥基因表达并允许杆形成的阈值浓度。为了测试我们的前馈假设对光感受器形成的含义，我们将利用我们和其他人在斑马鱼中产生的遗传工具。然后，我们将利用我们的知识来测试NR2E3中引起疾病的突变对饲喂前卫控制的影响。我们的研究将阐明锥体与ROD产生的分子控制，这将为开发视网膜替代疗法的实验室提供宝贵的信息，并深入了解遗传性视网膜变性疾病的本体发育。