Abstract
Resent studies have identified Pygopus as a core component of the β-catenin/T-cell factor (TCF)/lymphoid-enhancing factor 1 (LEF) transcriptional activation complex required for the expression of canonical Wg/Wnt target genes in Drosophila. However, the biochemical involvement of mammalian Pygopus proteins in β-catenin/TCF/LEF gene activation remains controversial. In this study, we perform a series of molecular/biochemical experiments to demonstrate that Pygo2 associates with histone-modifying enzymatic complexes, specifically the MLL2 histone methyltransferase (HMT) and STAGA histone acetyltransferase (HAT) complexes, to facilitate their interaction with β-catenin and to augment Wnt1-induced, TCF/LEF-dependent transcriptional activation in breast cancer cells. We identify a critical domain in Pygo2 encompassing the first 47 amino acids that mediates its HMT/HAT interaction. We further demonstrate the importance of this domain in Pygo2's ability to transcriptionally activate both artificial and endogenous Wnt target genes and to expand breast cancer stem-like cells in culture. This work now links mechanistically Pygo2's role in histone modification to its enhancement of the Wnt-dependent transcriptional program and cancer stem-like cell expansion.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Animals
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Breast Neoplasms* / enzymology
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Breast Neoplasms* / genetics
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Breast Neoplasms* / pathology
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Cell Line, Tumor
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Female
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Gene Expression Regulation, Neoplastic*
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HEK293 Cells
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Histones / genetics
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Histones / metabolism
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Humans
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Intracellular Signaling Peptides and Proteins / genetics
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Intracellular Signaling Peptides and Proteins / metabolism*
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Lymphoid Enhancer-Binding Factor 1 / genetics
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Lymphoid Enhancer-Binding Factor 1 / metabolism
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Neoplasm Proteins / genetics
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Neoplasm Proteins / metabolism*
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Neoplastic Stem Cells / cytology
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Neoplastic Stem Cells / physiology*
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Proto-Oncogene Proteins c-myc / genetics
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Proto-Oncogene Proteins c-myc / metabolism
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RNA Interference
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Wnt1 Protein / genetics
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Wnt1 Protein / metabolism
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p300-CBP Transcription Factors / genetics
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p300-CBP Transcription Factors / metabolism*
Substances
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DNA-Binding Proteins
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Histones
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Intracellular Signaling Peptides and Proteins
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KMT2D protein, human
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LEF1 protein, human
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Lymphoid Enhancer-Binding Factor 1
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MYC protein, human
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Neoplasm Proteins
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PYGO2 protein, human
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Proto-Oncogene Proteins c-myc
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WNT1 protein, human
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Wnt1 Protein
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p300-CBP Transcription Factors
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p300-CBP-associated factor