Husainy Asma N, Morrow Anne A, Perkins Theodore J, Lee Jonathan M
Department of Biochemistry, Microbiology & Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada.
BMC Cell Biol. 2010 Nov 17;11:86. doi: 10.1186/1471-2121-11-86.
Filopodia are actin-based cellular projections that have a critical role in initiating and sustaining directional migration in vertebrate cells. Filopodia are highly dynamic structures that show a rich diversity in appearance and behavior. While there are several mathematical models of filopodia initiation and growth, testing the capacity of these theoretical models in predicting empirical behavior has been hampered by a surprising shortage of quantitative data related to filopodia. Neither is it clear how quantitatively robust the cellular filopodial network is and how perturbations alter it.
We have measured the length and interfilopodial separation distances of several thousand filopodia in the rodent cell line Rat2 and measured these parameters in response to genetic, chemical and physical perturbation. Our work shows that length and separation distance have a lognormal pattern distribution over their entire detection range (0.4 μm to 50 μm).
We find that the lognormal distribution of length and separation is robust and highly resistant to perturbation. We also find that length and separation are independent variables. Most importantly, our empirical data is not entirely in agreement with predictions made based on existing theoretical models and that filopodial size and separation are an order of magnitude larger than what existing models suggest.
丝状伪足是基于肌动蛋白的细胞突起，在脊椎动物细胞启动和维持定向迁移中起关键作用。丝状伪足是高度动态的结构，在外观和行为上表现出丰富的多样性。虽然有几种丝状伪足起始和生长的数学模型，但由于与丝状伪足相关的定量数据惊人地短缺，测试这些理论模型预测实验行为的能力受到了阻碍。细胞丝状伪足网络在数量上的稳健程度以及扰动如何改变它也不清楚。
我们测量了啮齿动物细胞系Rat2中数千个丝状伪足的长度和丝状伪足间的间距，并测量了这些参数对基因、化学和物理扰动的响应。我们的研究表明，长度和间距在其整个检测范围内（0.4μm至50μm）呈对数正态模式分布。
我们发现长度和间距的对数正态分布是稳健的，并且对扰动具有高度抗性。我们还发现长度和间距是独立变量。最重要的是，我们的实验数据与基于现有理论模型的预测并不完全一致，并且丝状伪足的大小和间距比现有模型所表明的大一个数量级。
