Robust patterns in the stochastic organization of filopodia

Department of Biochemistry, Microbiology & Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada.
BMC Cell Biology (Impact Factor: 2.34). 11/2010; 11(1):86. DOI: 10.1186/1471-2121-11-86
Source: PubMed


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.

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Available from: Theodore Perkins, Feb 28, 2014
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    • "In our study, quantification of the minimum distance of attachment, an important parameter that would influence adhesion of NSCs/neurospheres in vitro, showed that a significant number of NSCs attached through filopodia of length greater than 6 µm, extending up to 12 µm. This is concurrent with the findings of Husainy et al. [31] who compiled thousands of filopodial length measurements in their fibroblast cell line. According to them such filopodial elongation could occur by loss of capping protein function or active G-actin transport within filopdia. "
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