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J Cell Sci. 2016 Oct 15;129(20):3892-3902.

Essential role of the Dishevelled DEP domain in a Wnt-dependent human-cell-based complementation assay.

Author information

1
MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK melissag@mrc-lmb.cam.ac.uk mb2@mrc-lmb.cam.ac.uk.
2
MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK.
3
Leslie Dan Faculty of Pharmacy, Room 901, University of Toronto, 144 College Street, Toronto, Ontario, Canada M5S 3M2.

Abstract

Dishevelled (DVL) assembles Wnt signalosomes through dynamic head-to-tail polymerisation by means of its DIX domain. It thus transduces Wnt signals to cytoplasmic effectors including β-catenin, to control cell fates during normal development, tissue homeostasis and also in cancer. To date, most functional studies of Dishevelled relied on its Wnt-independent signalling activity resulting from overexpression, which is sufficient to trigger polymerisation, bypassing the requirement for Wnt signals. Here, we generate a human cell line devoid of endogenous Dishevelled (DVL1- DVL3), which lacks Wnt signal transduction to β-catenin. However, Wnt responses can be restored by DVL2 stably re-expressed at near-endogenous levels. Using this assay to test mutant DVL2, we show that its DEP domain is essential, whereas its PDZ domain is dispensable, for signalling to β-catenin. Our results imply two mutually exclusive functions of the DEP domain in Wnt signal transduction - binding to Frizzled to recruit Dishevelled to the receptor complex, and dimerising to cross-link DIX domain polymers for signalosome assembly. Our assay avoids the caveats associated with overexpressing Dishevelled, and provides a powerful tool for rigorous functional tests of this pivotal human signalling protein.

KEYWORDS:

DEP domain; Dishevelled; Frizzled; PDZ domain

PMID:
27744318
PMCID:
PMC5087658
DOI:
10.1242/jcs.195685
[Indexed for MEDLINE]
Free PMC Article

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