title: Automated analysis of filopodial length and spatially resolved protein concentration via adaptive shape tracking.
abstract: Filopodia are dynamic, actin-rich structures that transiently form on a variety of cell types. To understand the underlying control mechanisms requires precise monitoring of localization and concentration of individual regulatory and structural proteins as filopodia elongate and subsequently retract. Although several methods exist that analyze changes in filopodial shape, a software solution to reliably correlate growth dynamics with spatially resolved protein concentration along the filopodium independent of bending, lateral shift, or tilting is missing. Here we introduce a novel approach based on the convex-hull algorithm for parallel analysis of growth dynamics and relative spatiotemporal protein concentration along flexible filopodial protrusions. Detailed in silico tests using various geometries confirm that our technique accurately tracks growth dynamics and relative protein concentration along the filopodial length for a broad range of signal distributions. To validate our technique in living cells, we measure filopodial dynamics and quantify spatiotemporal localization of filopodia-associated proteins during the filopodial extension-retraction cycle in a variety of cell types in vitro and in vivo. Together these results show that the technique is suitable for simultaneous analysis of growth dynamics and spatiotemporal protein enrichment along filopodia. To allow readily application by other laboratories, we share source code and instructions for software handling.
authors.affiliation: DFG Cluster of Excellence Cells in Motion (EXC 1003), University of Münster, 48149 Münster, Germany.|Institute of Medical Physics and Biophysics, University of Münster, 48149 Münster, Germany.
authors.forename: Tanumoy
authors.initials: T
authors.lastname: Saha
authors.affiliation: DFG Cluster of Excellence Cells in Motion (EXC 1003), University of Münster, 48149 Münster, Germany.|Institute of Medical Physics and Biophysics, University of Münster, 48149 Münster, Germany.
authors.forename: Isabel
authors.initials: I
authors.lastname: Rathmann
authors.affiliation: DFG Cluster of Excellence Cells in Motion (EXC 1003), University of Münster, 48149 Münster, Germany.|Institute of Medical Physics and Biophysics, University of Münster, 48149 Münster, Germany.
authors.forename: Abhiyan
authors.initials: A
authors.lastname: Viplav
authors.affiliation: DFG Cluster of Excellence Cells in Motion (EXC 1003), University of Münster, 48149 Münster, Germany.|Institute of Cell Biology, University of Münster, 48149 Münster, Germany.
authors.forename: Sadhana
authors.initials: S
authors.lastname: Panzade
authors.affiliation: DFG Cluster of Excellence Cells in Motion (EXC 1003), University of Münster, 48149 Münster, Germany.|Institute of Medical Physics and Biophysics, University of Münster, 48149 Münster, Germany.
authors.forename: Isabell
authors.initials: I
authors.lastname: Begemann
authors.affiliation: Institute of Medical Physics and Biophysics, University of Münster, 48149 Münster, Germany.
authors.forename: Christiane
authors.initials: C
authors.lastname: Rasch
authors.affiliation: DFG Cluster of Excellence Cells in Motion (EXC 1003), University of Münster, 48149 Münster, Germany.|Institute of Medical Physics and Biophysics, University of Münster, 48149 Münster, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Klingauf
authors.affiliation: DFG Cluster of Excellence Cells in Motion (EXC 1003), University of Münster, 48149 Münster, Germany.|Institute of Cell Biology, University of Münster, 48149 Münster, Germany.
authors.forename: Maja
authors.initials: M
authors.lastname: Matis
authors.affiliation: DFG Cluster of Excellence Cells in Motion (EXC 1003), University of Münster, 48149 Münster, Germany galic@uni-muenster.de.|Institute of Medical Physics and Biophysics, University of Münster, 48149 Münster, Germany.
authors.forename: Milos
authors.initials: M
authors.lastname: Galic
mesh_terms: D000199:Actins / Q000378:metabolism; D000465:Algorithms; D048430:Cell Shape / Q000502:physiology; D003198:Computer Simulation; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D011554:Pseudopodia / Q000378:metabolism / Q000502:physiology*; D012984:Software; D062211:Spatio-Temporal Analysis; D013223:Statistics as Topic / Q000379:methods*
chemical_list: D000199:Actins