Bistability and trigger waves in cell signaling

细胞信号传导中的双稳态和触发波

• 批准号: 10361534
• 负责人: JAMES E. FERRELL
• 金额: $ 68.59万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-01 至 2024-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10361534
• 关键词: Action Potentials; Apoptosis; Apoptotic; Axon; Biological Pacemakers; Biological Process; Biology; Calcium Oscillations; Cell Cycle Regulation; Cells; Centrosome; Cilia; Cytoplasm; Dendrites; Diffuse; Enzymes; Evolution; Feedback; Fire - disasters; Infection; Innate Immune Response; Innate Immune System; Interferons; Internet; Interphase; Light; Microfluidic Microchips; Mitosis; Mitotic; Modeling; Natural regeneration; Organism; Process; Protein Phosphatase 2A Regulatory Subunit PR53; Proteins; Signal Transduction; Structure; System; Temperature; Testing; Tissues; Tube; Variant; Work; Xenopus; Xenopus laevis; base; egg; experimental study; fascinate; process repeatability; response; theories

PROJECT SUMMARY/ABSTRACT We have been studying cell cycle regulation in Xenopus laevis eggs and extracts, carrying out a combination of quantitative experiments and modeling to understand how this biological oscillator works and what features it shares with other regulatory systems. The oscillator circuit includes a positive feedback-based bistable trigger, which opens the possibility that Cdk1 activity might spread through cytoplasm by what are termed trigger waves: self-regenerating activity waves, where some active Cdk1 diffuses a small distance and brings about the activation of the inactive Cdk1 in that volume through the positive feedback, which then diffuses locally and repeats the process. Action potentials are trigger waves; so are calcium waves, as is the spread of a fire through a field or the spread of a joke on the internet. We recently showed that both mitosis and apoptosis spread through Xenopus cytoplasm via trigger waves. We plan to build upon this, and determine: · What mechanism underpins the ability of interphase Xenopus cytoplasm to self-organize into cell-like structures? This was an unexpected observation we made in the course of our apoptosis studies, and it is a fascinating phenomenon to try to understand. · Is the apoptotic control circuit a bistable system? Our discovery of apoptotic trigger waves suggests that it is, but others have argued that it may not be. We plan to settle the issue with direct experiments. · Saltatory vs. continuous mitotic waves. We plan to see whether Cdk1 activation propagates differently close to vs. far from the centrosome, where various pro-mitotic proteins concentrate. · Can bistability restrict signals to certain compartments? Theory tells us that a trigger wave may be blocked at the junction between a small tube and a big tube, like a dendrite/axon junction or the base of a primary cilium. We plan to carry out experiments with apoptotic trigger waves in microfluidics devices to test whether this does occur. · Do innate immune responses spread via trigger waves? The innate immune system includes positive feedback loops, such as interferon-induced interferon release. This could allow cellular defenses to spread ahead of an infection in a sheet of cells. We plan to test this possibility experimentally. · Is there a second mitotic switch? We have found that bistability persists when Cdk1 activity is forced to be graded. Our working hypothesis is that double-negative feedback loops centered on PP2A-B55 are responsible for this bistability. We are testing this hypothesis with hysteresis experiments in extracts. · How to proteins that work together stay coordinated as temperature changes, especially in cold-blood organisms? Do enzymes that work together have similar activation energies and Q10 values? And/or has evolution selected particular circuits that tolerate high degrees of parameter variation?

项目概要/摘要 我们一直在研究非洲爪蟾卵和提取物的细胞周期调控，并进行了组合 定量实验和建模，以了解这种生物振荡器的工作原理和特征 它与其他监管体系共享。振荡器电路包括基于正反馈的双稳态 触发器，这开启了 Cdk1 活性可能通过所谓的通过细胞质传播的可能性 触发波：自我再生活动波，其中一些活性 Cdk1 扩散一小段距离并带来 关于通过正反馈激活该体积中不活跃的 Cdk1，然后扩散 本地并重复该过程。动作电位是触发波；钙波也是如此，传播也是如此 田野起火或互联网上流传的笑话。我们最近表明，有丝分裂和 细胞凋亡通过触发波通过非洲爪蟾细胞质传播。我们计划以此为基础，并确定： · 爪蟾间期细胞质自组织成细胞样能力的机制是什么？ 结构？这是我们在细胞凋亡研究过程中意外观察到的结果，它 这是一个值得尝试去理解的迷人现象。 · 细胞凋亡控制电路是双稳态系统吗？我们对细胞凋亡触发波的发现表明 确实如此，但其他人认为可能不是。我们计划通过直接实验来解决这个问题。 · 突变波与连续有丝分裂波。我们计划看看 Cdk1 激活是否以不同的方式传播 靠近或远离中心体，各种促有丝分裂蛋白集中在中心体。 · 双稳态能否限制信号到达某些隔室？理论告诉我们触发波可能是 阻塞在小管和大管之间的连接处，例如树突/轴突连接处或树突底部 初级纤毛。我们计划在微流体装置中进行细胞凋亡触发波实验 来测试是否会发生这种情况。 · 先天免疫反应是否通过触发波传播？先天免疫系统包括阳性 反馈回路，例如干扰素诱导的干扰素释放。这可以让细胞防御 在一片细胞感染之前传播。我们计划通过实验来测试这种可能性。 · 是否存在第二个有丝分裂开关？我们发现，当 Cdk1 活性被迫降低时，双稳态仍然存在。 被评分。我们的工作假设是，以 PP2A-B55 为中心的双负反馈环是 造成这种双稳态的原因。我们正在通过提取物的滞后实验来检验这一假设。 · 协同工作的蛋白质如何在温度变化时保持协调，尤其是在冷血中 有机体？协同作用的酶是否具有相似的活化能和 Q10 值？和/或 进化是否选择了能够容忍高度参数变化的特定电路？