Multicomponent mechanochemical regulation of actin filament end dynamics

摘要 细胞肌动蛋白动力学在许多关键过程中是必不可少的，如细胞迁移、伤口愈合、细胞 分裂和内吞作用。生理性肌动蛋白动力学源于蛋白质之间复杂的相互作用 影响新的肌动蛋白结构的组装或现有肌动蛋白的分解的机制 结构。在过去的几十年里，调节细胞内肌动蛋白动态的蛋白质过多 被识别的和单独的特征。然而，我们仍然不完全了解这些蛋白质是如何工作的。 以及它们如何导致无法简单预测的紧急行为 通过添加他们已知的个人活动。在过去的几年里，我发现了几个这样的 多组分活动。我证明了肌动蛋白生长的促进剂(福尔明)和阻滞剂(封闭蛋白) 可以同时结合同一个位点上的肌动蛋白细丝，在这个过程中发起自己的动态交换 在灯丝末端。我还完成了第一个直接的显微演示，展示了一个预测已久但从未实现的 环化酶相关蛋白(CAP)促进肌动蛋白细丝的点端解聚 和Cofilin。在接下来的五年里，我们的目标是揭示多组分生化信号和 机械信号在单个肌动蛋白细丝的尺度上被整合。我们将在我们开创性的基础上 通过研究我们已经鉴定的其他蛋白质的发现，这些蛋白质要么直接结合细丝末端，要么通过 其他末端结合蛋白。我们还将研究机械力如何改变肌动蛋白的生化相互作用。 与肌动蛋白细丝结合的蛋白质。为了做到这一点，我们将采用一种独特的微流体辅助组合 (MF-TIRF)和多光谱单分子成像，这是我在过去几年中开创的。我们会 将生化和生物物理实验与数学建模相结合。我的愿景是更好的 了解肌动蛋白动力学的分子机制将为开发新的 与肌萎缩侧索硬化症(ALS)、转移性癌症、神经系统疾病等人类疾病作斗争的疗法 (如阿尔茨海默病和帕金森氏病)和发育障碍(如肢体畸形) 是由于与肌动蛋白动力学相关的异常引起的。

ABSTRACT Cellular actin dynamics are essential in a number of key processes such as cell migration, wound healing, cell division and endocytosis. Physiological actin dynamics arises from a complex interplay between protein machineries that influence either the assembly of new actin structures or the disassembly of existing actin structures. Over the last few decades, a plethora of proteins regulating actin dynamics in cells have been identified and individually characterized. However, we still do not fully understand how these proteins work together in multiprotein ecosystems and how they give rise to emergent behavior that cannot be predicted simply by adding their known individual activities. Over the last few years, I have discovered several such multicomponent activities. I showed that an enhancer (formin) and a blocker (capping protein) of actin growth can simultaneously bind the same site on an actin filament, in the process initiating their own dynamic exchanges at filament ends. I also accomplished the first direct microscopic demonstration of a long-predicted but never observed acceleration of pointed-end depolymerization of actin filaments by cyclase-associated protein (CAP) and cofilin. Over the next five years, our goal is to uncover how multicomponent biochemical signals and mechanical signals get integrated at the scale of individual actin filaments. We will build on our ground-breaking discoveries by investigating other proteins that we have identified, which either directly bind filament ends or via other end-binding proteins. We will also investigate how mechanical forces alter biochemical interactions of actin binding proteins with actin filaments. To do this, we will employ a unique combination of microfluidics-assisted (mf-TIRF) and multispectral single molecule imaging that I have pioneered over the last few years. We will combine biochemical and biophysical experiments with mathematical modelling. My vision is that a better understanding of molecular mechanisms underlying actin dynamics will pave the way for development of new therapies to combat human ailments like Amyotrophic Lateral Sclerosis (ALS), metastatic cancer, neurological (e.g. Alzheimer's disease and Parkinson's diseases) and developmental disorders (e.g. limb deformities) that are caused due to abnormalities related to actin dynamics.