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

基本信息

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
项目类别：
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

项目摘要

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（由申请人提供）：我们最近证明，Cdk1/Cdc25/Wee1 系统的双稳定性允许 Cdk1 激活通过所谓的触发波、激活波和失活波在非洲爪蟾细胞质中快速传播，从而传播动作电位这项工作是通过开发与荧光显微镜兼容并允许循环提取物进行的聚四氟乙烯管系统而实现的。 Cdk1 触发波的速度 (~60 µm/min) 足以解释完整分裂之前发生的有丝分裂和表面收缩波 (SCW) 的动态。这项工作去年发表在《自然》杂志上。我们建议通过分为三个具体目标的研究来构建这项工作：目标 1. 卵子、卵母细胞和提取物中的有丝分裂和减数分裂触发波。我们还计划检查有丝分裂波之间的相互作用，这有助于防止 Cdk1 激活的异位灶破坏第一个细胞。最后，我们计划描述卵母细胞中新发现的减数分裂触发波现象的机制和意义，我们怀疑这种现象可能与第一极体的排出和减数分裂的完成有关。 1. 目标 2. 细胞间耦合和多细胞胚胎的同步一旦受精卵开始分裂，保持单个卵裂球内有丝分裂空间协调的问题就变得不那么成问题，但保持不同细胞之间有丝分裂协调的问题就变得更成问题。在初步研究中，我们已经表明，当胚胎因短暂的温度梯度而失去同步时，细胞随后会恢复同步，几种机制（单独或共同）可以解释这种同步，包括通过通信。我们计划通过完整胚胎和卵提取物的实验来测试这些想法。细胞凋亡的空间协调包括多个正反馈环，可以产生双稳定性并有助于确保细胞凋亡。我们计划使用非洲爪蟾卵提取物作为模型系统来测试 caspase 激活实际上是否是双稳态的。那么这种双稳态可能允许细胞凋亡状态通过触发波在卵中快速传播。初步研究表明情况确实如此：细胞凋亡状态显然以约 15 µm/min 的恒定速度在爪蟾细胞质中传播。我们计划表征特氟龙管提取系统中的这些波，并剖析产生它们的反馈回路。