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Dishevelled activates Ca2+ flux, PKC, and CamKII in vertebrate embryos.

Sheldahl LC, Slusarski DC, Pandur P, Miller JR, Kühl M, Moon RT - J. Cell Biol. (2003)

Bottom Line: Here we show that a Dsh deletion construct, XDshDeltaDIX, which is sufficient for activation of the PCP pathway, is also sufficient for activation of three effectors of the Wnt-Ca2+ pathway: Ca2+ flux, PKC, and calcium/calmodulin-dependent protein kinase II (CamKII).Furthermore, we find that interfering with endogenous Dsh function reduces the activation of PKC by Xfz7 and interferes with normal heart development.These data suggest that the Wnt-Ca2+ pathway utilizes Dsh, thereby implicating Dsh as a component of all reported Fz signaling pathways.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, Department of Pharmacology, University of Washington School of Medicine, Seattle, WA 98195, USA.

ABSTRACT
Wnt ligands and Frizzled (Fz) receptors have been shown to activate multiple intracellular signaling pathways. Activation of the Wnt-beta-catenin pathway has been described in greatest detail, but it has been reported that Wnts and Fzs also activate vertebrate planar cell polarity (PCP) and Wnt-Ca2+ pathways. Although the intracellular protein Dishevelled (Dsh) plays a dual role in both the Wnt-beta-catenin and the PCP pathways, its potential involvement in the Wnt-Ca2+ pathway has not been investigated. Here we show that a Dsh deletion construct, XDshDeltaDIX, which is sufficient for activation of the PCP pathway, is also sufficient for activation of three effectors of the Wnt-Ca2+ pathway: Ca2+ flux, PKC, and calcium/calmodulin-dependent protein kinase II (CamKII). Furthermore, we find that interfering with endogenous Dsh function reduces the activation of PKC by Xfz7 and interferes with normal heart development. These data suggest that the Wnt-Ca2+ pathway utilizes Dsh, thereby implicating Dsh as a component of all reported Fz signaling pathways.

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XDshΔDIX activates CamKII activity in a PTX-insensitive manner. Two-cell-stage Xenopus embryos were injected with RNAs encoding Rfz2, XDsh–GFP, XDshΔDIX–GFP, or PTX and processed for an in vitro CamKII activity assay. Injection of wt XDsh–GFP RNA produces a mild increase in CamKII activity compared with control embryos, whereas Rfz2 and XDshΔDIX–GFP RNAs produce a twofold activation compared with control embryos. Activation of CamKII by XDshΔDIX–GFP, unlike Rfz2, was not sensitive to coexpression of PTX. CamKII is rarely induced above two to threefold in any system (for review see Kühl et al., 2000a).
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fig3: XDshΔDIX activates CamKII activity in a PTX-insensitive manner. Two-cell-stage Xenopus embryos were injected with RNAs encoding Rfz2, XDsh–GFP, XDshΔDIX–GFP, or PTX and processed for an in vitro CamKII activity assay. Injection of wt XDsh–GFP RNA produces a mild increase in CamKII activity compared with control embryos, whereas Rfz2 and XDshΔDIX–GFP RNAs produce a twofold activation compared with control embryos. Activation of CamKII by XDshΔDIX–GFP, unlike Rfz2, was not sensitive to coexpression of PTX. CamKII is rarely induced above two to threefold in any system (for review see Kühl et al., 2000a).

Mentions: As a third independent assay for the activation of the Wnt–Ca2+ pathway, we monitored activation of CamKII (Kühl et al., 2000a). Injection of XDshΔDIX or Rfz2 RNA at the two-cell stage resulted in a twofold activation of CamKII activity in Xenopus embryos at stage 7 before the onset of zygotic transcription (Fig. 3). Consistent with the observed increase in Ca2+ fluxes, injection of RNA encoding wt XDsh slightly increases CamKII activity. Whereas activation of CamKII by Rfz2 was sensitive to the A protomer of PTX, the effect of XDshΔDIX was insensitive to this treatment (Fig. 3). In summary, our data reveal that XDshΔDIX is able to activate three effectors of the Wnt–Ca2+ pathway, Ca2+, PKC, and CamKII, in a PTX-insensitive manner.


Dishevelled activates Ca2+ flux, PKC, and CamKII in vertebrate embryos.

Sheldahl LC, Slusarski DC, Pandur P, Miller JR, Kühl M, Moon RT - J. Cell Biol. (2003)

XDshΔDIX activates CamKII activity in a PTX-insensitive manner. Two-cell-stage Xenopus embryos were injected with RNAs encoding Rfz2, XDsh–GFP, XDshΔDIX–GFP, or PTX and processed for an in vitro CamKII activity assay. Injection of wt XDsh–GFP RNA produces a mild increase in CamKII activity compared with control embryos, whereas Rfz2 and XDshΔDIX–GFP RNAs produce a twofold activation compared with control embryos. Activation of CamKII by XDshΔDIX–GFP, unlike Rfz2, was not sensitive to coexpression of PTX. CamKII is rarely induced above two to threefold in any system (for review see Kühl et al., 2000a).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2199364&req=5

fig3: XDshΔDIX activates CamKII activity in a PTX-insensitive manner. Two-cell-stage Xenopus embryos were injected with RNAs encoding Rfz2, XDsh–GFP, XDshΔDIX–GFP, or PTX and processed for an in vitro CamKII activity assay. Injection of wt XDsh–GFP RNA produces a mild increase in CamKII activity compared with control embryos, whereas Rfz2 and XDshΔDIX–GFP RNAs produce a twofold activation compared with control embryos. Activation of CamKII by XDshΔDIX–GFP, unlike Rfz2, was not sensitive to coexpression of PTX. CamKII is rarely induced above two to threefold in any system (for review see Kühl et al., 2000a).
Mentions: As a third independent assay for the activation of the Wnt–Ca2+ pathway, we monitored activation of CamKII (Kühl et al., 2000a). Injection of XDshΔDIX or Rfz2 RNA at the two-cell stage resulted in a twofold activation of CamKII activity in Xenopus embryos at stage 7 before the onset of zygotic transcription (Fig. 3). Consistent with the observed increase in Ca2+ fluxes, injection of RNA encoding wt XDsh slightly increases CamKII activity. Whereas activation of CamKII by Rfz2 was sensitive to the A protomer of PTX, the effect of XDshΔDIX was insensitive to this treatment (Fig. 3). In summary, our data reveal that XDshΔDIX is able to activate three effectors of the Wnt–Ca2+ pathway, Ca2+, PKC, and CamKII, in a PTX-insensitive manner.

Bottom Line: Here we show that a Dsh deletion construct, XDshDeltaDIX, which is sufficient for activation of the PCP pathway, is also sufficient for activation of three effectors of the Wnt-Ca2+ pathway: Ca2+ flux, PKC, and calcium/calmodulin-dependent protein kinase II (CamKII).Furthermore, we find that interfering with endogenous Dsh function reduces the activation of PKC by Xfz7 and interferes with normal heart development.These data suggest that the Wnt-Ca2+ pathway utilizes Dsh, thereby implicating Dsh as a component of all reported Fz signaling pathways.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, Department of Pharmacology, University of Washington School of Medicine, Seattle, WA 98195, USA.

ABSTRACT
Wnt ligands and Frizzled (Fz) receptors have been shown to activate multiple intracellular signaling pathways. Activation of the Wnt-beta-catenin pathway has been described in greatest detail, but it has been reported that Wnts and Fzs also activate vertebrate planar cell polarity (PCP) and Wnt-Ca2+ pathways. Although the intracellular protein Dishevelled (Dsh) plays a dual role in both the Wnt-beta-catenin and the PCP pathways, its potential involvement in the Wnt-Ca2+ pathway has not been investigated. Here we show that a Dsh deletion construct, XDshDeltaDIX, which is sufficient for activation of the PCP pathway, is also sufficient for activation of three effectors of the Wnt-Ca2+ pathway: Ca2+ flux, PKC, and calcium/calmodulin-dependent protein kinase II (CamKII). Furthermore, we find that interfering with endogenous Dsh function reduces the activation of PKC by Xfz7 and interferes with normal heart development. These data suggest that the Wnt-Ca2+ pathway utilizes Dsh, thereby implicating Dsh as a component of all reported Fz signaling pathways.

Show MeSH