Expression of mRor2 Is Required for Wnt5a-Mediated Inhibition of Canonical Signaling
(A) In 293 cells, mRor2 overexpression inhibits Wnt5a-mediated activation of the STF reporter. The 293 and 293Fz4 cells were transiently transfected with the reporters and LRP5 with or without mRor2 and then treated with Wnt proteins for 24 h, 24 h post-transfection. Overexpression of wild-type mRor2 inhibits Wnt5a-mediated activation of the STF reporter as well as allowing Wnt5a to inhibit Wnt3a-mediated STF reporter activation in 293Fz4 cells.
(B) mRor2 overexpression inhibits Wnt5a-mediated activation of the STF reporter and allows Wnt5a to block Wnt3a-induced STF reporter activation in mouse L cells. L and LFz4 cells were transiently transfected with the reporters and LRP5 with or without mRor2 and then treated with Wnt proteins for 24 h, 24 h post-transfection.
(C) Quantitative real-time PCR analysis of Ror2 expression in 293 and L cells. Reverse transcription followed by 45 cycles of quantitative real-time amplification of 293 cell RNA reveals a robust Ror2 product that is over 700 times more abundant than that produced from RNA derived from mouse L cells. Hprt quantification serves as an internal normalization control and RNA derived from 293Ror2 and LRor2 cells serves as a positive control for the reaction. The products from the PCR analysis are displayed below the charted quantitative data.
(D) The cytoplasmic domain of mRor2 is required for its inhibitory function. Expression of a membrane-tethered variant of mRor2 possessing the extracellular domain of mRor2 fused to a GPI linkage (mRor2-GPI) reduces Wnt5a's ability to inhibit Wnt3a induced canonical Wnt signaling as well as inhibits wild type mRor2′s ability to enhance Wnt5a-mediated inhibition.
(E) Expression of a membrane-tethered variant of mRor2 (mRor2-TM) that contains the extracellular and transmembrane domains of mRor2, but lacks the cytoplasmic domain, does not enhance Wnt5a mediated inhibition of canonical Wnt signaling. Expression of mRor2-TM reduces Wnt5a's ability to inhibit Wnt3a-induced canonical Wnt signaling when wild-type mRor2 is overexpressed. Western blot analysis shows that wild-type mRor2 levels do not change when the truncated mRor2 variants are coexpressed.