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LEF-1 regulates β-catenin nuclear localization
following LEF-1 knockdown (Figure 7A and B). A signifi- cant reduction in Wnt signaling output was also observed following use of an alternative LEF1 shRNA in response to CHIR99021 or Wnt3a stimulation (Online Supplementary Figure S8). Assessment of the TCF reporter activity in the LEF1 over-expressing lines was not possible due to the
A
confounding expression of the GFP selectable marker; instead, we examined the protein expression of the classic downstream Wnt target proteins survivin, c-MYC and cyclinD1. We found that LEF1 overexpression significant- ly enhanced the expression of these proteins following CHIR99021 treatment (Figure 7C and D), indicating that
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D
Figure 4. Mass spectrometric analyses identify putative novel interaction partners for β-catenin in myeloid leukemia cell lines. Bar graphs summarizing the average fold change in protein binding (relative to matched IgG co-immunoprecipitation) for novel, significant β-catenin interactions observed in (A) K562 cytosolic, (B) K562 nuclear, (C) ML1 cytosolic, and (D) ML1 nuclear fractions. Significant proteins only are shown (red dots in Figure 3 panels) with a frequency on the CRAPome data- base of ≤10% and known interactions were removed. Red asterisks represent proteins of particular significance to myeloid leukemias and/or Wnt signaling (see Results). Proteins are ranked along x-axis according to statistical significance (most significant on the left) (see also Online Supplementary Table S2).
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