Protease-activated receptor-1 (PAR1) acts via a novel Galpha13-dishevelled axis to stabilize beta-catenin levels.
We have previously shown a novel link between hPar-1 (human protease-activated receptor-1) and beta-catenin stabilization. Although it is well recognized that Wnt signaling leads to beta-catenin accumulation, the role of PAR1 in the process is unknown. We provide here evidence that PAR1 induces beta-catenin stabilization independent of Wnt, Fz (Frizzled), and the co-receptor LRP5/6 (low density lipoprotein-related protein 5/6) and identify selective mediators of the PAR1-beta-catenin axis. Immunohistological analyses of hPar1-transgenic (TG) mouse mammary tissues show the expression of both Galpha(12) and Galpha(13) compared with age-matched control counterparts. However, only Galpha(13) was found to be actively involved in PAR1-induced beta-catenin stabilization. Indeed, a dominant negative form of Galpha(13) inhibited both PAR1-induced Matrigel invasion and Lef/Tcf (lymphoid enhancer factor/T cell factor) transcription activity. PAR1-Galpha(13) association is followed by the recruitment of DVL (Dishevelled), an upstream Wnt signaling protein via the DIX domain. Small interfering RNA-Dvl silencing leads to a reduction in PAR1-induced Matrigel invasion, inhibition of Lef/Tcf transcription activity, and decreased beta-catenin accumulation. It is of note that PAR1 also promotes the binding of beta-arrestin-2 to DVL, suggesting a role for beta-arrestin-2 in PAR1-induced DVL phosphorylation dynamics. Although infection of small interfering RNA-LRP5/6 or the use of the Wnt antagonists, SFRP2 (soluble Frizzled-related protein 2) or SFRP5 potently reduced Wnt3A-mediated beta-catenin accumulation, no effect was observed on PAR1-induced beta-catenin stabilization. Collectively, our data show that PAR1 mediates beta-catenin stabilization independent of Wnt. We propose here a novel cascade of PAR1-induced Galpha(13)-DVL axis in cancer and beta-catenin stabilization.
Department of Oncology, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel.
Hagit
H
Turm
Department of Oncology, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel.
Myriam
M
Maoz
Department of Oncology, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel.
Vered
V
Katz
Department of Oncology, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel.
Yong-Jun
YJ
Yin
Department of Pharmacology, Max-Planck-Institute for Heart and Lung Research, Ludwigstrasse 43, 61231 Bad Nauheim, Germany.
Steffan
S
Offermanns
Department of Oncology, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel. Electronic address: rachel.bar-shavit@ekmd.huji.ac.il.
Rachel
R
Bar-Shavit
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D019390:Arrestins / Q000378:metabolism; D002460:Cell Line; D000072261:Dishevelled Proteins; D044365:GTP-Binding Protein alpha Subunits, G12-G13 / Q000378:metabolism*; D020868:Gene Silencing; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice; D008822:Mice, Transgenic; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D044463:Receptor, PAR-1 / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism*; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins
C000605254:ARRB2 protein, human; D048868:Adaptor Proteins, Signal Transducing; C000605258:Arrb2 protein, mouse; D019390:Arrestins; D000072261:Dishevelled Proteins; D010750:Phosphoproteins; D044463:Receptor, PAR-1; D051176:beta Catenin; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins; D044365:GTP-Binding Protein alpha Subunits, G12-G13