Dishevelled-3 C-terminal His single amino acid repeats are obligate for Wnt5a activation of non-canonical signaling

Li Ma,Craig C Malbon,Ying Wang,Hsien-Yu Wang

doi:10.1186/1750-2187-5-19

Li Ma, Craig C Malbon + Show 2 more

Open Access

https://doi.org/10.1186/1750-2187-5-19

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Abstract

BackgroundThe Wnt non-canonical pathway (Wnt5a > Frizzled-2 > cyclic GMP phosphodiesterase/Ca2+-mobilization pathway regulates the activation of NF-AT) is mediated by three mammalian Dishevelleds (Dvl1, Dvl2, and Dvl3) and the role of the C-terminal region unique to Dvl3 was interrogated.ResultsDvl1, Dvl2, and Dvl3 are expressed at varying levels in mouse totipotent F9 embryonal teratocarcinoma cells. The expression of each endogenous Dvl isoform, as defined by knock-down with siRNA, was obligate for Wnt5a to activate NF-AT-sensitive transcription. Elements upstream of effectors, e.g., cGMP phosphodiesterase and Ca2+-mobilization, were blocked by knock-down of any one of the Dvls; thus, with respect to Wnt5a activation of NF-AT Dvls are not redundant. Among the three Dvl isoforms, the C-terminal sequence of Dvl3 is the most divergent. Deletion of region of Dvl3 abolishes Wnt5a-stimulated signaling. Alanine (Ala)-substitution of histidine (His) single amino acid repeats at 637,638 and/or 647,648 in Dvl3, like C-terminal deletion, abolishes Wnt 5a signal propagation. Phenylalanine (Phe)-substitution of the same His-repeats in Dvl3 mimics Wnt5a stimulated NF-AT-sensitive transcription.ConclusionsThe C-terminal third of Dvl3 and His single amino acid repeats 637,638 and 647,648 (which are unique to and conserved in Dvl3) are essential for Wnt5a activation of the non-canonical pathway, but not the Wnt3a activation of the canonical pathway.

Highlights

The Wnt non-canonical pathway (Wnt5a > Frizzled-2 > cyclic GMP phosphodiesterase/Ca2 +-mobilization pathway regulates the activation of Nuclear Factor of Activated T cells (NF-AT)) is mediated by three mammalian Dishevelleds (Dvl1, Dvl2, and Dvl3) and the role of the C-terminal region unique to Dvl3 was interrogated
Upon treatment with Wnt5a, F9 cells differentiate into primitive endoderm, characteristic of early mouse development [8]
Stimulating F9 cells with Wnt5a provoked activation of NF-AT-sensitive transcription (Figure 1A). This marked activation of NF-ATsensitive gene transcription was provoked in cells expressing Frizzled-2, but not in those expressing either Frizzled-1 (Fz1) or empty vector (EV)

Summary

Introduction

The Wnt non-canonical pathway (Wnt5a > Frizzled-2 > cyclic GMP phosphodiesterase/Ca2 +-mobilization pathway regulates the activation of NF-AT) is mediated by three mammalian Dishevelleds (Dvl, Dvl, and Dvl3) and the role of the C-terminal region unique to Dvl was interrogated. Wnt5a, operating via Frizzled-2, leads to activation of cyclic GMP phosphodiesterase (cGMP PDE) [30,31,32], a decline in intracellular cyclic GMP, and sharp transient increase of intracellular Ca2 [32,33,34,35]. This Wnt5a-stimulated mobilization of Ca2+ activates the protein phosphatase, calcineurin, which dephosphorylates a transcription factor, the Nuclear Factor of Activated T cells (NF-AT). That WNT5A is a cancerassociated gene implicated in the invasion and metastasis of several human cancers, including colorectal [37], breast and pancreas [38], heightens the need to more fully understand the function and dysfunction of the Wnt non-canonical pathway

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