Induction of a β-catenin-LEF-1 complex by wnt-1 and transforming mutants of β-catenin

Porfiri, Emilio; Rubinfeld, Bonnee; Albert, Iris; Hovanes, Karine; Waterman, Marian L.; Polakis, Paul

doi:10.1038/sj.onc.1201462

Cited by 141 publications

(116 citation statements)

References 28 publications

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“…As seen by others (Caca et al, 1999;Korinek et al, 1997;Morin et al, 1997;Por®ri et al, 1997) and consistent with the increased levels of b-catenin protein discussed previously ( Figure 2a), transfection of cells with the S37A version of bcatenin resulted in a dramatic increase in the transactivation of the reporter relative to wild type bcatenin expression plasmid. In contrast, the wild type and S28A plakoglobin expression plasmids were similar in their ability to transactivate the reporter.…”

Section: Creation Of Chimeric Proteins To Identify Functional Domainssupporting

confidence: 62%

“…As previously reported for similar mutants in b-catenin Por®ri et al, 1997;Rubinfeld et al, 1997;Yost et al, 1996), immunoblot analysis of lysates (Figure 2a). In contrast, expression of the S28A mutant form of plakoglobin did not increase soluble plakoglobin above the amounts seen in cells transfected with plasmid encoding wild type plakoglobin (Figure 2a).…”

Section: Expression Of Exogenous B-catenin and Plakoglobin Reveals DImentioning

confidence: 71%

“…Endogenous or exogenous expression of serine/ threonine point mutants in b-catenin is known to increase transcription at TCF/LEF target gene promoters Por®ri et al, 1997;Rubinfeld et al, 1997). Introduction of as little as 0.2 mg (data not shown) or as much as 3.0 mg of S37A b-catenin plasmid DNA into 293T cells potently transactivated the OT reporter, roughly 80-fold over baseline (Figure 2c).…”

Section: Expression Of Exogenous B-catenin and Plakoglobin Reveals DImentioning

confidence: 99%

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A comparative evaluation of β-catenin and plakoglobin signaling activity

et al. 2000

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Vertebrates have two Armadillo-like proteins, b-catenin and plakoglobin. Mutant forms of b-catenin with oncogenic activity are found in many human tumors, but plakoglobin mutations are not commonly found. In fact, plakoglobin has been proposed to suppress tumorigenesis. To assess di erences between b-catenin and plakoglobin, we compared several of their biochemical properties. After transient transfection of 293T cells with an expression vector encoding either of the two proteins, soluble wild type b-catenin does not signi®-cantly accumulate, whereas soluble wild type plakoglobin is readily detected. As anticipated, b-catenin is stabilized by the oncogenic mutation S37A; however, the analogous mutation in plakoglobin (S28A) does not alter its halflife. S37A-b-catenin activates a TCF/LEF-dependent reporter 20-fold more potently than wild type b-catenin, and *5-fold more potently than wild type or S28A plakoglobin. These di erences may be attributable to an enhanced a nity of S37A b-catenin for LEF1 and TCF4, as observed here by immunoprecipitation assays. We show that the carboxyl-terminal domain is largely responsible for the di erence in signaling and that the Armadillo repeats account for the remainder of the di erence. The relatively weak signaling by plakoglobin and the failure of the S28A mutation to enhance its stability, may explain why plakoglobin mutations are infrequent in malignancies. Oncogene (2000) 19, 5720 ± 5728.

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Section: Creation Of Chimeric Proteins To Identify Functional Domainssupporting

confidence: 62%

Section: Expression Of Exogenous B-catenin and Plakoglobin Reveals DImentioning

confidence: 71%

Section: Expression Of Exogenous B-catenin and Plakoglobin Reveals DImentioning

confidence: 99%

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A comparative evaluation of β-catenin and plakoglobin signaling activity

et al. 2000

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“…In epithelial cells such as MDCK cells, almost all the bcatenin co-fractionates and co-immunoprecipitates with APC and cadherin in the high molecular weight fraction. However, in colorectal cancer cells such as SW480 cells, b-catenin appears in the high and the low molecular weight fractions and a b-catenin/Lef-1 complex is detected (Por®ri et al, 1997). These results suggest that b-catenin distributes between the high and low molecular weight fractions depending on binding partners.…”

Section: Discussionmentioning

confidence: 92%

Axin prevents Wnt-3a-induced accumulation of β-catenin

et al. 1999

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When Axin, a negative regulator of the Wnt signaling pathway, was expressed in COS cells, it coeluted with glycogen synthase kinase-3b (GSK-3b), b-catenin, and adenomatous polyposis coli protein (APC) in a high molecular weight fraction on gel ®ltration column chromatography. In this fraction, GSK-3b, b-catenin, and APC were co-precipitated with Axin. Although bcatenin was detected in the high molecular weight fraction in L cells on gel ®ltration column chromatography, addition of conditioned medium expressing Wnt3a to the cells increased b-catenin in the low molecular weight fraction. However, Wnt-3a-dependent accumulation of b-catenin was greatly inhibited in L cells stably expressing Axin. Axin also suppressed Wnt-3a-dependent activation of Tcf-4 which binds to b-catenin and acts as a transcription factor. These results suggest that Axin forms a complex with GSK-3b, b-catenin, and APC, resulting in the stimulation of the degradation of bcatenin and that Wnt-3a induces the dissociation of bcatenin from the Axin complex and accumulates bcatenin.

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“…p300, ALY, mSin3A, TLE, and HDAC6) to regulate tissue-specific gene expression (13-16). Runx1-dependent trans-activation of the T cell receptor enhancer is also increased indirectly by DNA-binding proteins, such as LEF1, 1 which bends DNA to facilitate long distance cooperative interactions between Runx1 and Ets1 (17, 18).LEF1 is a high mobility group (HMG) protein and nuclear effector of the canonical Wnt signaling pathway (19,20). LEF1 binds the consensus DNA sequence C/TCTTTGAA in the minor groove, creates a 130°bend in the double helix, and alters of binding of other transcription factors to neighboring sites (17,21).…”

mentioning

confidence: 99%

Lymphoid Enhancer Factor-1 and ॆ-Catenin Inhibit Runx2-dependent Transcriptional Activation of the Osteocalcin Promoter

Kahler

Westendorf

2003

Journal of Biological Chemistry

184

150

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Functional control of the transcription factor Runx2 is crucial for normal bone formation. Runx2 is detectable throughout osteoblast development and maturation and temporally regulates several bone-specific genes. In this study, we identified a novel post-translational mechanism regulating Runx2-dependent activation of the osteocalcin promoter. A functional binding site for the high mobility group protein lymphoid enhancerbinding factor 1 (LEF1) was found adjacent to the proximal Runx2-binding site in the osteocalcin promoter. In transcription assays, LEF1 repressed Runx2-induced activation of the mouse osteocalcin 2 promoter in several osteoblast lineage cell lines. Mutations in the LEF1-binding site increased the basal activity of the osteocalcin promoter; however, the LEF1 recognition site in the osteocalcin promoter was surprisingly not required for LEF1 repression. A novel interaction between the DNAbinding domains of Runx2 and LEF1 was identified and found crucial for LEF1-mediated repression of Runx2. LEF1 is a nuclear effector of the Wnt/LRP5/␤-catenin signaling pathway, which is also essential for osteoblast proliferation and normal skeletal development. A constitutively active ␤-catenin enhanced LEF1-dependent repression of Runx2. These data identify a novel mechanism of regulating Runx2 activity in osteoblasts and link Runx2 transcriptional activity to ␤-catenin signaling.Runx2 (Cbfa1, AML-3, PEBP2␣A) is one of three mammalian Runt domain factors and is essential for bone formation (1). Runx2 deficiency is developmentally lethal because it inhibits osteoblast development, chondrocyte differentiation in some skeletal elements, and vascular invasion into cartilage to prevent skeletal ossification (2-4). Moreover, a dominant-negative Runx2 protein prevents osteoblast differentiation in adult mice without decreasing osteoblast numbers (5). Runx2 haploinsufficiency hinders intramembranous bone formation and causes the rare skeletal disorder, cleidocranial dysplasia (6). Interestingly, Runx2 overexpression induces bone fragility by blocking osteoblast differentiation and enhancing bone resorption (7,8).These genetic studies demonstrate that cellular control of Runx2 expression levels and function is crucial for skeletal development.At the molecular level, Runx2 activity is regulated by multiple transcriptional and post-translational mechanisms (9). Runx proteins activate or repress gene expression by binding the DNA sequence, TGPuGGTPu (10). Runx-binding sites are often necessary but are not sufficient for transcriptional regulation of tissue-specific genes; thus, it has been hypothesized that Runx proteins are organizers that facilitate the assembly of transcriptional regulatory complexes on gene regulatory elements (11,12). Runx factors, in fact, interact with numerous transcription factors (e.g. AP1, C/EBP, Ets1, and SMADs) and transcriptional co-factors (e.g. p300, ALY, mSin3A, TLE, and HDAC6) to regulate tissue-specific gene expression (13-16). Runx1-dependent trans-activation of the T cell receptor en...

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Induction of a β-catenin-LEF-1 complex by wnt-1 and transforming mutants of β-catenin

Cited by 141 publications

References 28 publications

A comparative evaluation of β-catenin and plakoglobin signaling activity

A comparative evaluation of β-catenin and plakoglobin signaling activity

Axin prevents Wnt-3a-induced accumulation of β-catenin

Lymphoid Enhancer Factor-1 and ॆ-Catenin Inhibit Runx2-dependent Transcriptional Activation of the Osteocalcin Promoter

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