Trigger waves and coupled oscillations in the embryonic cell cycle

胚胎细胞周期中的触发波和耦合振荡

• 批准号: 9005870
• 负责人: JAMES E. FERRELL
• 金额: $ 31.92万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-02-15 至 2019-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9005870
• 关键词: Accounting; Action Potentials; Animals; Apoptosis; Apoptotic; Attention; Axon; Behavior; Biochemistry; Biological Models; Biological Process; Calcium Oscillations; Caliber; Cardiovascular system; Caspase; Cell Cycle; Cell Death; Cell Nucleus; Cells; Centrosome; Communication; Complex; Congresses; Coupled; Coupling; Cyclic AMP; Cytoplasm; Development; Diffuse; Diffusion; Elements; Embryo; Ensure; Event; Evolution; Feedback; Fluorescence Microscopy; Gap Junctions; Generations; Health; Hour; Individual; Meiosis; Mitosis; Mitotic; Modeling; Nature; Neurons; Oocytes; Phase; Physarum polycephalum; Process; Property; Protein Phosphatase 2A Regulatory Subunit PR53; Proteins; Publishing; Regulation; Role; Side; Speed; Stimulus; Surface; System; Teflon; Temperature; Testing; Time; Tissues; Tube; Walking; Work; Xenopus; Xenopus laevis; blastomere structure; cell cortex; cytochrome c; egg; embryo stage 2; research study; zygote; Accounting; Action Potentials; Animals; Apoptosis; Apoptotic; Attention; Axon; Behavior; Biochemistry; Biological Models; Biological Process; Calcium Oscillations; Caliber; Cardiovascular system; Caspase; Cell Cycle; Cell Death; Cell Nucleus; Cells; Centrosome; Communication; Complex; Congresses; Coupled; Coupling; Cyclic AMP; Cytoplasm; Development; Diffuse; Diffusion; Elements; Embryo; Ensure; Event; Evolution; Feedback; Fluorescence Microscopy; Gap Junctions; Generations; Health; Hour; Individual; Meiosis; Mitosis; Mitotic; Modeling; Nature; Neurons; Oocytes; Phase; Physarum polycephalum; Process; Property; Protein Phosphatase 2A Regulatory Subunit PR53; Proteins; Publishing; Regulation; Role; Side; Speed; Stimulus; Surface; System; Teflon; Temperature; Testing; Time; Tissues; Tube; Walking; Work; Xenopus; Xenopus laevis; blastomere structure; cell cortex; cytochrome c; egg; embryo stage 2; research study; zygote

DESCRIPTION (provided by applicant): Recently we demonstrated that the bistability of the Cdk1/Cdc25/Wee1 system allows Cdk1 activation to propagate rapidly through Xenopus cytoplasm by means of what are termed trigger waves, waves of activation and inactivation that spread the way action potentials spread down an axon. This work was made possible through the development of a Teflon tube system that is compatible with fluorescence microscopy and allows cycling extracts to carry out a dozen or more complete cell cycles without dying. The speed of the Cdk1 trigger wave (~60 �m/min) is sufficient to account for the dynamics of mitosis and of the surface contraction waves (SCWs) that occur prior to cleavage in intact embryos. This work was published last year in Nature. We propose to build upon this work through studies divided into three Specific Aims: Aim 1. Mitotic and meiotic trigger waves in eggs, oocytes, and extracts. We now plan to examine mitotic waves in greater spatial detail and examine the roles of nuclei and centrosomes in the generation and propagation of these waves. We also plan to examine the interplay between mitotic waves, which we suspect helps keep ectopic foci of Cdk1 activation from disorganizing the first cell cycle. Finally, we plan to characterize the mechanism and significance of a newly discovered meiotic trigger wave phenomenon in oocytes, which we suspect may be involved in the expulsion of the first polar body and the completion of meiosis 1. Aim 2. Intercellular coupling and the synchronization of multicellular embryos. Once the fertilized egg begins to divide, the issue of keeping mitosis spatially coordinated within individual blastomeres becomes less problematic, but the issue of keeping mitosis coordinated between separate cells becomes more problematic. In preliminary studies we have shown that when an embryo is desynchronized with a transitory temperature gradient, the cells subsequently return toward synchrony. Several mechanisms, singly or together, may explain this synchronization, including communication through cytoplasmic bridges, gap junctions, and cytoskeletal elements. We plan to test these ideas through experiments in intact embryos and egg extracts. Aim 3. Spatial coordination of apoptosis. The caspase system includes multiple positive feedback loops that could generate bistability and help ensure that apoptosis is all-or-none and irreversible in character. We plan to test whether caspase activation is, in fact, bistable, using Xenopus egg extracts as a model system. If it is, then it is possible that this bistability allows the apoptotic state to propagate rapidly through te egg via trigger waves. Preliminary studies indicate that this is the case: the apoptotic state apparently propagates through Xenopus cytoplasm at a constant speed of ~15 �m/min. We plan to characterize these waves in the Teflon tube extract system and to dissect the feedback loops that generate them.

描述（由适用提供）：最近我们证明了CDK1/CDC25/WEE1系统的双稳定性允许CDK1激活通过称为触发波，激活波和灭活的触发波，通过触发波传播的方式快速通过爪蟾细胞质传播，从而使动作电位扩散到轴突中。通过与荧光显微镜兼容的特氟龙管系统的开发，使这项工作成为可能，并且可以使循环提取物在不死亡的情况下进行十几个或更完整的细胞周期。 CDK1触发波（〜60 | m/min）的速度足以说明有丝分裂的动力学和表面收缩波（SCW）（SCWS）（SCWS）发生在完整的胚胎中之前发生的。这项工作于去年出版。我们建议通过研究分为三个特定目的的研究来建立这项工作：目标1。卵，卵母细胞和提取物中的有丝分裂和减数分裂触发波。现在，我们计划以更大的空间细节检查有丝分裂波，并检查核和中心体在这些波的产生和传播中的作用。我们还计划检查有丝分裂波之间的相互作用，我们怀疑这有助于防止CDK1激活的生态焦点破坏第一个细胞周期。最后，我们计划表征新发现的卵母细胞中新发现的减数分裂触发波现象的机制和意义，我们怀疑这可能参与第一个极性体的驱逐和减数分裂1的完成。一旦受精卵开始分裂，保持有丝分裂的问题经常在单个胚泡内进行协调的问题就会变得更少，但是保持有丝分裂在单独细胞之间协调的问题变得更加有问题。在初步研究中，我们已经表明，当胚胎用旋转温度梯度使胚胎对同步时，细胞随后返回同步。几种机制可以单独或一起解释这种同步，包括通过细胞质桥，间隙连接和细胞骨架元素进行通信。我们计划通过完整的胚胎和鸡蛋提取物进行实验来测试这些想法。目标3。凋亡的空间协调。 caspase系统包括多个可以产生双重性的正反馈回路，并有助于确保凋亡在特征上是无与伦比的，并且不可逆。我们计划使用爪蟾鸡蛋提取物作为模型系统来测试caspase激活是否是可动的。如果是这样，那么这种双重性可能会允许凋亡状态通过触发波快速通过TE卵传播。初步研究表明，情况就是这样：凋亡状态显然以〜15°m/min的恒定速度通过爪蟾传播。我们计划在Teflon管提取系统中表征这些波，并剖析产生它们的反馈回路。