Model of turnover kinetics in the lamellipodium: implications of slow- and fast- diffusing capping protein and Arp2/3 complex.
Model of turnover kinetics in the lamellipodium: implications of slow- and fast- diffusing capping protein and Arp2/3 complex.
复制标题
DOI：
10.1088/1478-3975/13/6/066009
复制
发表时间：
2016-12-06
期刊：
影响因子：
2
通讯作者：
Vavylonis D
中科院分区：
文献类型：
--
作者：
McMillen LM;Vavylonis D
通过运动细胞前沿的肌动蛋白细丝聚合形成的细胞突起可能受到扩散肌动蛋白和调节剂的空间梯度的影响。在这里，我们研究了两个最重要的调节因子，封闭蛋白和Arp2/3复合体的分布，它们通过封顶和自由倒刺末端的成核来调节肌动蛋白在片状隆起中的聚合。我们使用之前在XTC细胞上进行的单分子显微镜实验数据对它们的动力学进行了建模。这些实验为覆盖蛋白和Arp2/3复合体的扩散系数的广泛分布提供了证据。缓慢扩散的蛋白质看起来像是延伸的“云”，而与肌动蛋白细丝网络结合的蛋白质看起来像是逆行流动的斑点。斑点出现和消失事件对应于肌动蛋白细丝网络的组装和解离，斑点寿命对应于解离速率。缓慢扩散的覆盖蛋白可能代表被切断的覆盖的肌动蛋白细丝片段或膜结合的覆盖蛋白。先前的证据表明，缓慢扩散的Apr2/3复合体与膜有关。我们在蒙特卡罗模拟中使用测量的覆盖蛋白质和Arp2/3复合体的速率和扩散系数估计，该模拟包括与丝状网络相关的颗粒和在细胞质中扩散的颗粒。我们考虑两个不同的扩散蛋白质池，分别代表快速扩散和缓慢扩散的物种。我们发现了一个具有浓度梯度的稳定状态，涉及快、慢物质扩散流与逆流的平衡。我们表明，FRAP的模拟与先前在不同细胞类型上进行的实验是一致的。我们估计了结合络合物与扩散络合物的比率，并计算了Arp2/3络合物通过扩散循环可能成为极限的条件。我们讨论了种群缓慢扩散的含义，并建议进行实验，以区分影响长距离运输的机制。
Cell protrusion through polymerization of actin filaments at the leading edge of motile cells may be influenced by spatial gradients of diffuse actin and regulators. Here we study the distribution of two of the most important regulators, capping protein and Arp2/3 complex, which regulate actin polymerization in the lamellipodium through capping and nucleation of free barbed ends. We modeled their kinetics using data from prior single molecule microscopy experiments on XTC cells. These experiments have provided evidence for a broad distribution of diffusion coefficients of both capping protein and Arp2/3 complex. The slowly-diffusing proteins appear as extended “clouds” while proteins bound to the actin filament network appear as speckles that undergo retrograde flow. Speckle appearance and disappearance events correspond to assembly and dissociation from the actin filament network and speckle lifetimes correspond to the dissociation rate. The slowly-diffusing capping protein could represent severed capped actin filament fragments or membrane-bound capping protein. Prior evidence suggests that slowly-diffusing Apr2/3 complex associates with the membrane. We use the measured rates and estimates of diffusion coefficients of capping protein and Arp2/3 complex in a Monte Carlo simulation that includes particles in association with a filament network and diffuse in the cytoplasm. We consider two separate pools of diffuse proteins, representing fast and slowly-diffusing species. We find a steady state with concentration gradients involving a balance of diffusive flow of fast and slow species with retrograde flow. We show that simulations of FRAP are consistent with prior experiments performed on different cell types. We provide estimates for the ratio of bound to diffuse complexes and calculate conditions where Arp2/3 complex recycling by diffusion may become limiting. We discuss the implications of slowly diffusing populations and suggest experiments to distinguish among mechanisms that influence long range transport.
登录
查看更多内容
影响因子：
4.4
作者：
Lewalle A;Fritzsche M;Wilson K;Thorogate R;Duke T;Charras G
通讯作者：
Charras G
影响因子：
16.6
作者：
Jansen, Silvia;Collins, Agnieszka;Chin, Samantha M.;Ydenberg, Casey A.;Gelles, Jeff;Goode, Bruce L.
通讯作者：
Goode, Bruce L.
影响因子：
2.9
作者：
Kapustina, Maryna;Vitriol, Eric;Elston, Timothy C.;Loew, Leslie M.;Jacobson, Ken
通讯作者：
Jacobson, Ken
DOI：
10.1073/pnas.1313738111
发表时间：
2014-05-13
影响因子：
11.1
作者：
Fujiwara, Ikuko;Remmert, Kirsten;Hammer, John A.
通讯作者：
Hammer, John A.
影响因子：
3.4
作者：
Ditlev, Jonathon A.;Vacanti, Nathaniel M.;Loew, Leslie M.
通讯作者：
Loew, Leslie M.