title: The WTX Tumor Suppressor Interacts with the Transcriptional Corepressor TRIM28.
abstract: WTX encodes a tumor suppressor implicated in the pediatric kidney cancer Wilms tumor and in mesenchymal differentiation with potentially distinct functions in the cytoplasm, at the plasma membrane, and in the nucleus. Although modulating components of the WNT signaling pathway is a proposed function for cytoplasmic and membrane-bound WTX, its nuclear properties are not well understood. Here we report that the transcriptional corepressor TRIM28 is the major binding partner for nuclear WTX. WTX interacted with the coiled coil domain of TRIM28 required for its binding to Krüppel-associated box domains of transcription factors and for its chromatin recruitment through its own coiled coil and proline-rich domains. Knockdown of endogenous WTX reduced the recruitment of TRIM28 to a chromatinized reporter sequence and its ability to repress a target transcript. In mouse embryonic stem cells where TRIM28 plays a major role in repressing endogenous retroviruses and long interspersed elements, knockdown of either TRIM28 or WTX combined with single molecule RNA sequencing revealed a highly significant shared set of differentially regulated transcripts, including derepression of non-coding repetitive sequences and their neighboring protein encoding genes (p < 1e-20). In mesenchymal precursor cells, depletion of WTX and TRIM28 resulted in analogous β-catenin-independent defects in adipogenic and osteogenic differentiation, and knockdown of WTX reduced TRIM28 binding to Pparγ promoter. Together, the physical and functional interaction between WTX and TRIM28 suggests that the nuclear fraction of WTX plays a role in epigenetic silencing, an effect that may contribute to its function as a regulator of cellular differentiation and tumorigenesis.
authors.affiliation: Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, Massachusetts 02129 and.
authors.forename: Woo Jae
authors.initials: WJ
authors.lastname: Kim
authors.affiliation: Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, Massachusetts 02129 and.
authors.forename: Ben S
authors.initials: BS
authors.lastname: Wittner
authors.affiliation: Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, Massachusetts 02129 and.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Amzallag
authors.affiliation: Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, Massachusetts 02129 and.
authors.forename: Brian W
authors.initials: BW
authors.lastname: Brannigan
authors.affiliation: Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, Massachusetts 02129 and From the Departments of Medicine and.
authors.forename: David T
authors.initials: DT
authors.lastname: Ting
authors.affiliation: Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, Massachusetts 02129 and From the Departments of Medicine and.
authors.forename: Sridhar
authors.initials: S
authors.lastname: Ramaswamy
authors.affiliation: Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, Massachusetts 02129 and Surgery.
authors.forename: Shyamala
authors.initials: S
authors.lastname: Maheswaran
authors.affiliation: Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, Massachusetts 02129 and From the Departments of Medicine and Howard Hughes Medical Institute, Chevy Chase, Maryland 20815 Haber@helix.mgh.harvard.edu.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Haber
mesh_terms: D050156:Adipogenesis; D000818:Animals; D002460:Cell Line; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D060066:Protein Interaction Maps; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D000076183:Tripartite Motif-Containing Protein 28; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D009396:Wilms Tumor / Q000235:genetics / Q000378:metabolism
chemical_list: D002843:Chromatin; D009687:Nuclear Proteins; D012097:Repressor Proteins; D025521:Tumor Suppressor Proteins; C000600446:WTX protein, mouse; C103190:Trim28 protein, mouse; D000076183:Tripartite Motif-Containing Protein 28
keywords: TRIM28; WTX; Wilms tumor; epigenetics; heterochromatin; protein-protein interaction; transcription repressor; tumor suppressor gene