TY - JOUR
T1 - Wnt-4 activates the canonical β-catenin-mediated Wnt pathway and binds Frizzled-6 CRD
T2 - Functional implications of Wnt/β-catenin activity in kidney epithelial cells
AU - Lyons, Jon P.
AU - Mueller, Ulrich W.
AU - Ji, Hong
AU - Everett, Christopher
AU - Fang, Xiang
AU - Hsieh, Jen Chih
AU - Barth, Angelai M.
AU - McCrea, Pierre D.
N1 - Funding Information:
We are grateful to the following individuals for providing reagents, advice, and/or results before publication: A.P. McMahon (Harvard U.), D. Kimelman (U. Washington), J. Nathans (John's Hopkins U.), Y. Wang (John's Hopkins U.), W.J. Nelson (Stanford U.), A.L. Pollock (U. Arizona), K.E. Mostov (UCSF), M.C. Hung (UT MDACC), S. Dayal (UT MDACC), S.W. Kim (UT MDACC), T.G. Vaught (UT MDACC), and K.M. Ramirez (UT MDACC). This work was supported in part by National Institutes of Health (NIH) RO1 Grant GM 52112, Pharmacia/Monsanto Research Award, Cancer Center Support Grant Funds CCSG-CA 16672 (to P.D.M.), National Institutes of Health Training Grant GM-5-T32-HD07325 (to J.P.L. and U.W.M.), and American Legion Auxiliary Fellowship (to J.P.L.). DNA sequencing and flow cytometry core facilities were supported by the University of Texas M.D. Anderson Cancer Center NCI Core Grant CA-16672.
PY - 2004/8/15
Y1 - 2004/8/15
N2 - The Wnt signaling pathway is central to the development of all animals and to cancer progression, yet largely unknown are the pairings of secreted Wnt ligands to their respective Frizzled transmembrane receptors or, in many cases, the relative contributions of canonical (β-catenin/LEF/TCF) versus noncanonical Wnt signals. Specifically, in the kidney where Wnt-4 is essential for the mesenchymal to epithelial transition that generates the tissue's collecting tubules, the corresponding Frizzled receptor(s) and downstream signaling mechanism(s) are unclear. In this report, we addressed these issues using Madin-Darby Canine Kidney (MDCK) cells, which are competent to form tubules in vitro. Employing established reporter constructs of canonical Wnt/β-catenin pathway activity, we have determined that MDCK cells are highly responsive to Wnt-4, -1, and -3A, but not to Wnt-5A and control conditions, precisely reflecting functional findings from Wnt-4 null kidney mesenchyme ex vivo rescue studies. We have confirmed that Wnt-4's canonical signaling activity in MDCK cells is mediated by downstream effectors of the Wnt/β-catenin pathway using β-Engrailed and dnTCF-4 constructs that suppress this pathway. We have further found that MDCK cells express the Frizzled-6 receptor and that Wnt-4 forms a biochemical complex with the Frizzled-6 CRD. Since Frizzled-6 did not appear to transduce Wnt-4's canonical signal, data supported recently by Golan et al. [J. Biol. Chem. 249 (2004) 14978], there presumably exists another as yet unknown Frizzled receptor(s) mediating Wnt-4 activation of β-catenin/LEF/TCF. Finally, we report that canonical Wnt/β-catenin signals cells help maintain cell growth and survival in MDCK cells but do not contribute to standard HGF-induced (nonphysiologic) tubule formation. Our results in combination with work from Xenopus laevis (not shown) lead us to believe that Wnt-4 binds both canonical and noncanonical Frizzled receptors, thereby activating Wnt signaling pathways that may each contribute to kidney tubulogenesis.
AB - The Wnt signaling pathway is central to the development of all animals and to cancer progression, yet largely unknown are the pairings of secreted Wnt ligands to their respective Frizzled transmembrane receptors or, in many cases, the relative contributions of canonical (β-catenin/LEF/TCF) versus noncanonical Wnt signals. Specifically, in the kidney where Wnt-4 is essential for the mesenchymal to epithelial transition that generates the tissue's collecting tubules, the corresponding Frizzled receptor(s) and downstream signaling mechanism(s) are unclear. In this report, we addressed these issues using Madin-Darby Canine Kidney (MDCK) cells, which are competent to form tubules in vitro. Employing established reporter constructs of canonical Wnt/β-catenin pathway activity, we have determined that MDCK cells are highly responsive to Wnt-4, -1, and -3A, but not to Wnt-5A and control conditions, precisely reflecting functional findings from Wnt-4 null kidney mesenchyme ex vivo rescue studies. We have confirmed that Wnt-4's canonical signaling activity in MDCK cells is mediated by downstream effectors of the Wnt/β-catenin pathway using β-Engrailed and dnTCF-4 constructs that suppress this pathway. We have further found that MDCK cells express the Frizzled-6 receptor and that Wnt-4 forms a biochemical complex with the Frizzled-6 CRD. Since Frizzled-6 did not appear to transduce Wnt-4's canonical signal, data supported recently by Golan et al. [J. Biol. Chem. 249 (2004) 14978], there presumably exists another as yet unknown Frizzled receptor(s) mediating Wnt-4 activation of β-catenin/LEF/TCF. Finally, we report that canonical Wnt/β-catenin signals cells help maintain cell growth and survival in MDCK cells but do not contribute to standard HGF-induced (nonphysiologic) tubule formation. Our results in combination with work from Xenopus laevis (not shown) lead us to believe that Wnt-4 binds both canonical and noncanonical Frizzled receptors, thereby activating Wnt signaling pathways that may each contribute to kidney tubulogenesis.
KW - Kidney development
KW - MDCK
KW - Tubulogenesis
KW - ΔN131
KW - ΔN90
KW - β-Engrailed
UR - http://www.scopus.com/inward/record.url?scp=3242681470&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=3242681470&partnerID=8YFLogxK
U2 - 10.1016/j.yexcr.2004.04.036
DO - 10.1016/j.yexcr.2004.04.036
M3 - Article
C2 - 15265686
AN - SCOPUS:3242681470
SN - 0014-4827
VL - 298
SP - 369
EP - 387
JO - Experimental Cell Research
JF - Experimental Cell Research
IS - 2
ER -