Regulation of the actin filament pointed end dynamics in health and disease

参与心肌/骨骼肌收缩的细丝的变化通常会导致 有致命后果的心肌病/线虫性肌病。我们的长期目标是确定 肌肉正常发育和发育过程中肌动蛋白结构的调节成分和分子机制 疾病。在正在进行的拨款支持的提案中，我们的短期目标是确定 肌动蛋白末端结合蛋白leiomodin(Lmod)和Lmod对细丝长度的调节 妥莫定(Tmod)。尖端聚合决定细丝长度，直接调节 通过Tmod和Lmod的结合。这种结合通过整体的细丝组件来增强， 原肌球蛋白。我们推测，维持细丝长度需要Tmod的拮抗作用 和Lmod；也就是说，Tmod的作用是防止尖端的伸长，而Lmod允许伸长。 我们还预测Tmod和Lmod在指端的结合和作用是由不同的 它们的原肌球蛋白和肌动蛋白结合位点的排列。在我们提交的续订建议书中，我们将评估 Lmod和Tmod如何影响细丝的形成和结构。我们将测试我们最近的 Lmod/Tmod依赖的薄层尖端调控的分子机制 细丝。我们还将研究Lmod绑定到已经存在的 形成了细丝。最后，我们将建立LMOD功能的调节机制。我们的数据将提供 细丝调控机制的关键组成部分的综合鉴定 健康和疾病中的组装和维护。拟议的实验将连接LMOD相关的薄片 家族性肌病的肌丝改变。更好地理解细丝的功能及其调节 对于更好地了解肌肉疾病的发病机制、改进诊断和潜在地识别 新的药物靶点。

Alterations in the thin filaments involved in cardiac/skeletal muscle contraction often produce cardiomyopathies/nemaline myopathies with fatal consequences. Our long-term goal is to identify the components and molecular mechanisms regulating actin architecture in muscle during normal development and disease. In the proposal supported by the ongoing grant, our short-term goal is to determine the mechanisms of how thin filament lengths are regulated by the actin filament pointed end binding proteins, leiomodin (Lmod) and tropomoduin (Tmod). Polymerization at the pointed end determines thin filament length and is regulated directly by the binding of Tmod and Lmod. This binding is enhanced by the integral thin filament component, tropomyosin. We hypothesize that maintenance of thin filament length requires the antagonistic action of Tmod and Lmod; that is, the role of Tmod is to prevent elongation at the pointed end while Lmod allows elongation. We also predict that Tmod and Lmod binding and action at the pointed end is determined by different arrangements of their tropomyosin- and actin-binding sites. In our submitted renewal proposal, we will evaluate how Lmod and Tmod affect the formation and then the structure of the thin filament. We will test our recently proposed molecular mechanism for the Lmod/Tmod-dependent regulation of the pointed end of the thin filaments. We will also study the structural and functional consequences of Lmod binding to sides of the already formed thin filaments. Finally, we will establish mechanisms of regulation of Lmod functions. Our data will provide a comprehensive identification of critical components of the regulatory mechanisms underlying thin filament assembly and maintenance in health and disease.The proposed experiments will connect Lmod-related thin filament alterations with familial myopathies. A better understanding of thin filament function and of its regulation is critical to better understand muscle disease pathogenesis, to improve diagnostics and to potentially identify novel drug targets.