Cell cycle in development and regeneration of the inner ear

内耳发育和再生中的细胞周期

• 批准号: 7211123
• 负责人: Neil Segil
• 金额: $ 39.63万
• 依托单位: HOUSE RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2011-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7211123
• 关键词: Address; Adult; Affect; Age; Birds; Cell Count; Cell Cycle; Cell Cycle Regulation; Cell Death; Cell Differentiation process; Cell Proliferation; Cell division; Cells; Cochlea; Cochlear duct; Complex; Corwin; Cyclin-Dependent Kinase Inhibitor; Data; Defect; Development; Differentiation and Growth; Disruption; Down-Regulation; Embryonic Development; F-Box Proteins; Failure; Family; Figs - dietary; Genes; Genetic; Genetic Transcription; Goals; Grant; Hair Cells; In Vitro; Investigation; Labyrinth; Maintenance; Mammals; Methods; Molecular; Morphogenesis; Mus; Mutant Strains Mice; Natural regeneration; Normal Cell; Notch Signaling Pathway; Numbers; Organ; Organ of Corti; Pathway interactions; Pattern; Perinatal; Play; Point Mutation; Post-Transcriptional Regulation; Process; Proliferating; Proteins; Proteolysis; Publishing; Regulation; Relative (related person); Reporting; Research Personnel; Role; Ruthenium Ben; SKP Cullin F-Box Protein Ligases; Sensory Hair; Series; Signal Transduction; Supporting Cell; Techniques; Tertiary Protein Structure; Therapeutic Intervention; Time; Transcriptional Regulation; Ubiquitin; Vertebrates; Wild Type Mouse; age related; base; cyclin-dependent kinase inhibitor 1B; day; deafness; hair cell regeneration; in vivo; inhibitor/antagonist; insight; loss of function mutation; mutant; notch protein; postnatal; progenitor; programs; protein degradation; response; tool

DESCRIPTION (provided by applicant): Loss of sensory hair cells in mammals results in permanent deafness because regeneration does not occur. The loss of regenerative ability is tied to the inability of the specialized supporting cells within the organ of Corti to begin dividing in response to hair cell death. We have taken a developmental approach to this problem. Our hope is that by thoroughly understanding the process by which the cells of the organ of Corti stop dividing during embryogenesis, we will gain insight into why regeneration does not occur. In doing so, we hope to provide tools and targets for therapeutic intervention into the problem of deafness. During development of the organ of Corti, control of cell proliferation is tightly coordinated with the process of cell differentiation and patterning (Ruben, 1968). We have shown that the cyclin-dependent kinase inhibitor p27Kip1 is required for timing this coordination. In p27Kip1 mutant mice, cell cycle exit is delayed, leading to supernumerary cells, a disruption of the orderly pattern of hair cell organization, and deafness (Chen and Segil, 1999). Although p27Kip1 abundance is widely believed to be regulated at the post-transcriptional level through control of protein turnover, our results indicate that transcriptional regulation of p27Kip1 is largely, though not entirely, responsible for the determining the number of cells in the mature organ. Additional preliminary data indicates that Notch pathway signaling may be a key player in regulating p27 transcription during organ of Corti formation. In Specific Aim 1, we analyze the role of Notch signaling in the spatial and temporal regulation of p27Kip1 transcription during embryogenesis of the organ of Corti. In spite of the importance of p27Klp1 transcriptional regulation, we have observed that in Skp2 mutant mice, there is also a defect in cell cycle exit and organ of Corti structure. Skp2 is part of the SCF-ubiquitin ligase complex that is involved in regulating p27Kip1 protein turnover. In Specific Aim 2, we address the role of post-transcriptional mechanisms in the regulation of p27Kip1 Finally, in Specific Aims 3 and 4, we address the problem of regeneration directly, by studying p27Kip1 regulation in postnatal supporting cells. We have recently developed techniques that allow us to purify postnatal supporting cells and grow them in vitro. In doing so, we have discovered that perinatal supporting cells retain the capacity to reenter the cell cycle and divide, while supporting cells from P14 mice are unable to do so. Changes in the ability of P14 supporting cells to down-regulate p27Kip1 are partly responsible for the block to cell division that results in the lack of regeneration. This specific aim investigates the molecular basis for the age-dependent change in p27 regulation that we hypothesize underlies the lack of regeneration in the mammalian inner ear.

描述（由申请人提供）：哺乳动物感觉毛细胞的缺失会导致永久性耳聋，因为无法再生。再生能力的丧失与Corti器官内的特化支持细胞不能响应毛细胞死亡而开始分裂有关。我们对这一问题采取了发展的办法。我们的希望是，通过彻底了解胚胎发育过程中Corti器官细胞停止分裂的过程，我们将深入了解为什么再生不会发生。通过这样做，我们希望为耳聋问题的治疗干预提供工具和目标。在Corti器官的发育过程中，细胞增殖的控制与细胞分化和模式化的过程紧密协调（Ruben，1968）。我们已经表明，细胞周期蛋白依赖性激酶抑制剂p27 Kip 1是需要定时这种协调。在p27 Kip 1突变小鼠中，细胞周期退出延迟，导致多余细胞，毛细胞组织的有序模式被破坏，以及耳聋（Chen和Segil，1999）。虽然p27 Kip 1丰度被广泛认为是在转录后水平通过控制蛋白质周转调节，我们的研究结果表明，p27 Kip 1的转录调控在很大程度上，虽然不是完全，负责确定成熟器官中的细胞数量。额外的初步数据表明，Notch途径信号传导可能是在Corti器官形成过程中调节p27转录的关键参与者。在具体目标1中，我们分析了Notch信号在Corti器官胚胎发生过程中p27 Kip 1转录的时空调控中的作用。尽管p27 Klp 1转录调控的重要性，我们已经观察到，在Skp 2突变小鼠，也有一个缺陷，在细胞周期退出和器官的Corti结构。Skp 2是SCF-泛素连接酶复合物的一部分，参与调节p27 Kip 1蛋白周转。在具体目标2，我们解决的作用，转录后机制的调节p27 Kip 1最后，在具体目标3和4，我们直接解决再生的问题，通过研究p27 Kip 1调节产后支持细胞。我们最近开发了一种技术，使我们能够纯化出生后的支持细胞，并在体外培养。在这样做的过程中，我们发现围产期支持细胞保留了重新进入细胞周期和分裂的能力，而来自P14小鼠的支持细胞则无法这样做。P14支持细胞下调p27 Kip 1的能力的变化是导致缺乏再生的细胞分裂阻滞的部分原因。这个特定的目标调查的p27调控，我们假设的基础上缺乏再生的哺乳动物内耳的年龄依赖性变化的分子基础。