Analysis of Wnt signaling β-catenin spatial dynamics in HEK293T cells
1 Structural Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
2 Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
3 Ludwig Institute for Cancer Research, Melbourne-Parkville Branch, Parkville, VIC, Australia
4 Department of Infrastructure Engineering, University of Melbourne, Parkville, VIC, Australia
5 School of Computer Science and Software Engineering, The University of Western Australia, Perth, WA, Australia
6 Department of Surgery, University of Melbourne, Parkville, VIC, Australia
BMC Systems Biology 2014, 8:44 doi:10.1186/1752-0509-8-44Published: 8 April 2014
Wnt/β-catenin signaling is involved in different stages of mammalian development and implicated in various cancers (e.g. colorectal cancer). Recent experimental and computational studies have revealed characteristics of the pathway, however a cell-specific spatial perspective is lacking. In this study, a novel 3D confocal quantitation protocol is developed to acquire spatial (two cellular compartments: nucleus and cytosol-membrane) and temporal quantitative data on target protein (e.g. β-catenin) concentrations in Human Epithelial Kidney cells (HEK293T) during perturbation (with either cycloheximide or Wnt3A). Computational models of the Wnt pathway are constructed and interrogated based on this data.
A single compartment Wnt pathway model is compared with a simple β-catenin two compartment model to investigate Wnt3A signaling in HEK293T cells. When protein synthesis is inhibited, β-catenin decreases at the same rate in both cellular compartments, suggesting diffusional transport is fast compared to β-catenin degradation in the cytosol. With Wnt3A stimulation, the total amount of β-catenin rises throughout the cell, however the increase is initially (~first hour) faster in the nuclear compartment. While both models were able to reproduce the whole cell changes in β-catenin, only the compartment model reproduced the Wnt3A induced changes in β-catenin distribution and it was also the best fit for the data obtained when active transport was included alongside passive diffusion transport.
This integrated 3D quantitation imaging protocol and computational modeling approach allowed cell-specific compartment models of the signaling pathways to be constructed and analyzed. The Wnt models constructed in this study are the first for HEK293T and have suggested potential roles of inter-compartment transport to the dynamics of signaling.