Abstract
WNT/CTNNB1 signaling regulates tissue development and homeostasis in all multicellular animals. Multiple aspects of the underlying molecular mechanism remain poorly understood and critical information on endogenous WNT/CTNNB1 signaling dynamics is missing. Here we combine CRISPR/Cas9-mediated genome editing and quantitative live-cell microscopy to measure diffusion characteristics of fluorescently tagged, endogenous CTNNB1 in human cells with high spatiotemporal resolution. State-of-the-art functional imaging reveals that both in the absence and presence of WNT, a substantial fraction of CTNNB1 resides in slow-diffusing complexes in the cytoplasm and that WNT stimulation changes their identity. We also measure the concentration of complexed and free CTNNB1 in both the cytoplasm and the nucleus before and after WNT stimulation, and use these parameters to build a minimal computational model of WNT/CTNNB1 signaling. Our work reveals that WNT regulates the dynamic distribution of CTNNB1 across different functional pools by modulating the destruction complex, nucleocytoplasmic shuttling and nuclear retention.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
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