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This version published online on November 3, 2009
Endocrinology, doi:10.1210/en.2009-0557
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Submitted on May 14, 2009
Accepted on September 29, 2009

Wingless (Wnt)-3A Induces Trophoblast Migration and Matrix Metalloproteinase-2 Secretion through Canonical Wnt Signaling and Protein Kinase B/AKT Activation

Stefan Sonderegger, Peter Haslinger, Alia Sabri, Christina Leisser, Jan V. Otten, Christian Fiala, and Martin Knöfler*

Department of Obstetrics and Fetal-Maternal Medicine (S.S., P.H., A.S., C.L., J.V.O., M.K.), Reproductive Biology Unit, Medical University of Vienna, A-1090 Vienna, Austria; and Gynmed Clinic (C.F.), A-1150 Vienna, Austria

* To whom correspondence should be addressed. E-mail: martin.knoefler{at}meduniwien.ac.at.

Invasion of human trophoblasts is promoted through activation of wingless (Wnt) signaling, suggesting a role of the pathway in placental development and morphogenesis. However, details on the process such as involvement of canonical and/or noncanonical Wnt signaling cascades as well as their target genes are largely unknown. Hence, signal transduction via canonical Wnt signaling or phosphatidylinositide 3-kinase (PI3K)/AKT and their cross talk as well as trophoblast-specific protease expression were investigated in trophoblastic SGHPL-5 cells and primary extravillous trophoblasts purified from first-trimester placentas. Western blot analyses revealed that the recombinant Wnt ligand Wnt-3A increased phosphorylation of AKT and the downstream kinase glycogen synthase kinase (GSK)-3{beta} as well as accumulation of activated, nuclear {beta}-catenin. In accordance, luciferase expression of a canonical Wnt/TCF reporter and cell migration in first-trimester villous explant cultures and of SGHPL-5 cells were stimulated. Chemical inhibition of PI3K abolished Wnt-dependent phosphorylation of AKT and GSK-3{beta} and trophoblast motility but did not affect appearance of activated {beta}-catenin or Wnt/TCF reporter activity. In contrast, inhibition of the canonical pathway through soluble Dickkopf-1 did not influence AKT and GSK-3{beta} phosphorylation but reduced Wnt reporter activity, accumulation of active {beta}-catenin, and cell migration. Both inhibitors decreased Wnt-3A-induced secretion of pro- and active matrix metalloproteinase-2 from SGHPL-5 cells and pure EVT. The data suggest that Wnt-3A may activate canonical Wnt signaling and PI3K/AKT through distinct receptors. The two signaling cascades act independently in trophoblasts; however, both pathways promote Wnt-dependent migration and the release of matrix metalloproteinase-2, which has been identified as novel Wnt target in invasive trophoblasts.







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