ImaEdge – a platform for quantitative analysis of the spatiotemporal dynamics of cortical proteins during cell polarization

Abstract

Cell polarity involves the compartmentalization of the cell cortex. The establishment of cortical compartments arises from the spatial bias in the activity and concentration of cortical proteins. The mechanistic dissection of cell polarity requires the accurate detection of dynamic changes in cortical proteins, but the fluctuations of cell shape and the inhomogeneous distributions of cortical proteins greatly complicate the quantitative extraction of their global and local changes during cell polarization. To address these problems, we introduce an open-source software package, ImaEdge, which automates the segmentation of the cortex from time-lapse movies, and enables quantitative extraction of cortical protein intensities. We demonstrate that ImaEdge enables efficient and rigorous analysis of the dynamic evolution of cortical PAR proteins during embryogenesis. It is also capable of accurate tracking of varying levels of transgene expression and discontinuous signals of the actomyosin cytoskeleton during multiple rounds of cell division. ImaEdge provides a unique resource for quantitative studies of cortical polarization, with the potential for application to many types of polarized cells.This article has an associated First Person interview with the first authors of the paper.

Aurora-A Breaks Symmetry in Contractile Actomyosin Networks Independently of Its Role in Centrosome Maturation

“…To quantify dynamics of PKC-3::GFP and NMY-2::mKate at the cortex in live zygotes ( Figure S5), we used ImaEdge software (Zhang et al, 2017), which was designed for automatic extraction of the cell cortex region from each frame of time-lapse movies, followed by quantification of fluorescence intensity of proteins along the entire cell cortex. The cortical region was divided into 200 sampling windows.…”

A balance between antagonizing PAR proteins specifies the pattern of asymmetric and symmetric divisions in C. elegans embryogenesis

“…To quantify the distribution of PAR proteins at the cell cortex in live zygotes (Figure S2), we used ImaEdge software (Zhang et al, 2017), which was designed for automatic extraction of the cortex region from each frame of time-lapse movies. The cortical region along the entire circumference was divided into 100 sampling windows.…”