Project description:The myeloid translocation gene family member MTG16 is a transcriptional corepressor that relies on the DNA-binding ability of other proteins to determine specificity. One such protein is the ZBTB family member Kaiso, and the MTG16:Kaiso interaction is necessary for repression of Kaiso target genes such as matrix metalloproteinase-7. Using the azoxymethane and dextran sodium sulfate (AOM/DSS) murine model of colitis-associated carcinoma, we previously determined that MTG16 loss accelerates tumorigenesis and inflammation. However, it was unknown whether this effect was modified by Kaiso-dependent transcriptional repression. To test for a genetic interaction between MTG16 and Kaiso in inflammatory carcinogenesis, we subjected single and double knockout (DKO) mice to the AOM/DSS protocol. Mtg16-/- mice demonstrated increased colitis and tumor burden; in contrast, disease severity in Kaiso-/- mice was equivalent to wild type controls. Surprisingly, Kaiso deficiency in the context of MTG16 loss reversed injury and pro-tumorigenic responses in the intestinal epithelium following AOM/DSS treatment, and tumor numbers were returned to near to wild type levels. Transcriptomic analysis of non-tumor colon tissue demonstrated that changes induced by MTG16 loss were widely mitigated by concurrent Kaiso loss, and DKO mice demonstrated downregulation of metabolism and cytokine-associated gene sets with concurrent activation of DNA damage checkpoint pathways as compared with Mtg16-/-. Further, Kaiso knockdown in intestinal enteroids reduced stem- and WNT-associated phenotypes, thus abrogating the induction of these pathways observed in Mtg16-/- samples. Together, these data suggest that Kaiso modifies MTG16-driven inflammation and tumorigenesis and suggests that Kaiso deregulation contributes to MTG16-dependent colitis and CAC phenotypes.
Project description:Aberrant epithelial differentiation and regeneration contribute to colon pathologies, including inflammatory bowel disease (IBD) and colitis-associated cancer (CAC). Myeloid translocation gene 16 (MTG16, also known as CBFA2T3) is a transcriptional corepressor expressed in the colonic epithelium. MTG16 deficiency in mice exacerbates colitis and increases tumor burden in CAC, though the underlying mechanisms remain unclear. Here, we identified MTG16 as a central mediator of epithelial differentiation, promoting goblet and restraining enteroendocrine cell development in homeostasis and enabling regeneration following dextran sulfate sodium–induced (DSS-induced) colitis. Transcriptomic analyses implicated increased Ephrussi box–binding transcription factor (E protein) activity in MTG16-deficient colon crypts. Using a mouse model homozygous for a point mutation that attenuates MTG16:E protein interactions (Mtg16P209T), we showed that MTG16 exerts control over colonic epithelial differentiation and regeneration by repressing E protein–mediated transcription. Mimicking murine colitis, MTG16 expression was increased in biopsies from patients with active IBD compared with unaffected controls. Finally, uncoupling MTG16:E protein interactions partially phenocopied the enhanced tumorigenicity of Mtg16-null colon in the azoxymethane (AOM) /DSS-induced model of CAC, indicating that MTG16 protects from tumorigenesis through additional mechanisms. Collectively, our results demonstrate that MTG16, via its repression of E protein targets, is a key regulator of cell fate decisions during colon homeostasis, colitis, and cancer.
Project description:The myeloid translocation gene family member MTG16 is a transcriptional corepressor that relies on the DNA-binding ability of other proteins to determine specificity. One such protein is the ZBTB family member Kaiso, and the MTG16:Kaiso interaction is necessary for repression of Kaiso target genes, such as matrix metalloproteinase-7. Using the azoxymethane and dextran sodium sulfate (AOM/DSS) murine model of colitis-associated carcinoma, we previously determined that MTG16 loss accelerates tumorigenesis and inflammation. However, it was unknown whether this effect was modified by Kaiso-dependent transcriptional repression. To test for a genetic interaction between MTG16 and Kaiso in inflammatory carcinogenesis, we subjected single and double knockout (DKO) mice to the AOM/DSS protocol. Mtg16-/- mice demonstrated increased colitis and tumor burden; in contrast, disease severity in Kaiso-/- mice was equivalent to wild-type controls. Surprisingly, Kaiso deficiency in the context of MTG16 loss reversed injury and pro-tumorigenic responses in the intestinal epithelium following AOM/DSS treatment, and tumor numbers were returned to near to wild-type levels. Transcriptomic analysis of non-tumor colon tissue demonstrated that changes induced by MTG16 loss were widely mitigated by concurrent Kaiso loss, and DKO mice demonstrated downregulation of metabolism and cytokine-associated gene sets with concurrent activation of DNA damage checkpoint pathways as compared with Mtg16-/-. Further, Kaiso knockdown in intestinal enteroids reduced stem- and WNT-associated phenotypes, thus abrogating the induction of these pathways observed in Mtg16-/- samples. Together, these data suggest that Kaiso modifies MTG16-driven inflammation and tumorigenesis and suggests that Kaiso deregulation contributes to MTG16-dependent colitis and CAC phenotypes.
Project description:MTG16 is a member of the myeloid translocation gene (MTG) family of transcriptional corepressors. While MTGs were originally identified in chromosomal translocations in acute myeloid leukemia, recent studies have uncovered a role in intestinal biology. For example, Mtg16-/- mice have increased intestinal proliferation and are more sensitive to intestinal injury in colitis models. MTG16 is also underexpressed in patients with moderate/severe ulcerative colitis. Based on these findings, we postulated that MTG16 might protect against colitis-associated carcinogenesis. MTG16 was downregulated at the protein and RNA levels in patients with inflammatory bowel disease and in those with colitis-associated carcinoma. Mtg16-/- mice subjected to inflammatory carcinogenesis modeling exhibited worse colitis and increased tumor multiplicity and size. Loss of MTG16 also increased severity of dysplasia, apoptosis, proliferation, DNA damage, and WNT signaling. Moreover, transplantation of WT marrow into Mtg16-/- mice failed to rescue the Mtg16-/- protumorigenic phenotypes, indicating an epithelium-specific role for MTG16. While MTG dysfunction is widely appreciated in hematopoietic malignancies, the role of this gene family in epithelial homeostasis, and in colon cancer, was unrealized. This report identifies MTG16 as an important modulator of colitis and tumor development in inflammatory carcinogenesis.
Project description:E protein transcription factors specify major immune cell lineages including lymphocytes and interferon-producing plasmacytoid dendritic cells (pDCs). Corepressors of the ETO family can bind to and block transactivation by E proteins, but the physiological role of these interactions remained unclear. We report that ETO protein Mtg16 binds chromatin primarily through the pDC-specific E protein E2-2 in human pDCs. Mtg16-deficient mice showed impaired pDC development and functionality, whereas the specification of the classical dendritic cells (cDCs) was enhanced. The deletion of Mtg16 caused aberrant expression of E protein antagonist Id2 in pDCs. Thus, Mtg16 acts as a cofactor of E2-2 to promote pDC differentiation and restrict cDC development, revealing an unexpected positive role of ETO proteins in E protein activity. Analysis of E2-2 and Mtg16 immunoprecipitated chromatin from CAL-1 cell line.
Project description:E protein transcription factors specify major immune cell lineages including lymphocytes and interferon-producing plasmacytoid dendritic cells (pDCs). Corepressors of the ETO family can bind to and block transactivation by E proteins, but the physiological role of these interactions remained unclear. We report that ETO protein Mtg16 binds chromatin primarily through the pDC-specific E protein E2-2 in human pDCs. Mtg16-deficient mice showed impaired pDC development and functionality, whereas the specification of the classical dendritic cells (cDCs) was enhanced. The deletion of Mtg16 caused aberrant expression of E protein antagonist Id2 in pDCs. Thus, Mtg16 acts as a cofactor of E2-2 to promote pDC differentiation and restrict cDC development, revealing an unexpected positive role of ETO proteins in E protein activity. pDC from BM of WT and mtg16-KO mice were negatively selected (lin-CD19, Tcrb, Ter119, NK1.1) and sorted as CD11c+Bst2+ population directly in Trizol. RNA was prepared and deposited for microarray processing.
Project description:E protein transcription factors specify major immune cell lineages including lymphocytes and interferon-producing plasmacytoid dendritic cells (pDCs). Corepressors of the ETO family can bind to and block transactivation by E proteins, but the physiological role of these interactions remained unclear. We report that ETO protein Mtg16 binds chromatin primarily through the pDC-specific E protein E2-2 in human pDCs. Mtg16-deficient mice showed impaired pDC development and functionality, whereas the specification of the classical dendritic cells (cDCs) was enhanced. The deletion of Mtg16 caused aberrant expression of E protein antagonist Id2 in pDCs. Thus, Mtg16 acts as a cofactor of E2-2 to promote pDC differentiation and restrict cDC development, revealing an unexpected positive role of ETO proteins in E protein activity.
Project description:E protein transcription factors specify major immune cell lineages including lymphocytes and interferon-producing plasmacytoid dendritic cells (pDCs). Corepressors of the ETO family can bind to and block transactivation by E proteins, but the physiological role of these interactions remained unclear. We report that ETO protein Mtg16 binds chromatin primarily through the pDC-specific E protein E2-2 in human pDCs. Mtg16-deficient mice showed impaired pDC development and functionality, whereas the specification of the classical dendritic cells (cDCs) was enhanced. The deletion of Mtg16 caused aberrant expression of E protein antagonist Id2 in pDCs. Thus, Mtg16 acts as a cofactor of E2-2 to promote pDC differentiation and restrict cDC development, revealing an unexpected positive role of ETO proteins in E protein activity.
Project description:A single normal hematopoietic stem cell (HSC) is sufficient to regenerate the entire blood system after bone marrow transplantation. This process requires not only rapid mobilization of the stem cell into the cell cycle, but also the proliferation of committed progenitor cells to provide functional mature cells until HSC progeny have accumulated to sufficient numbers1. Gene disruption strategies have dissected the regulatory pathways and identified critical factors that mediate the decision of a stem cell to self-renew and quiesce or to enter the rapidly expanding progenitor cell pool to populate the various hematopoietic cell lineages. However, only a very limited number of the transcriptional regulators and chromatin remodeling factors that are recruited by DNA binding factors have been pinpointed as contributors to stem cell functions. Here, we show that the transcriptional co-repressor Myeloid Translocation Gene on chromosome 16 (Mtg16), which is targeted by the t(16;21) in acute myeloid leukemia, is required for long-term hematopoietic stem cell functions and suppression of stem cell mobilization. Although there are no dramatic defects in the allocation of cells to any of the major hematopoietic cell lineages, inactivation of Mtg16 impairs the rapid expansion of stem/progenitor cells, which is required after bone marrow transplantation. This impairment appears to be a failure to proliferate rather than an induction of cell death, as expression of c-Myc complements the Mtg16-/- defect. Keywords: Knock-out analysis, genetic modification