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Project description:The pseudokinase Trib1 functions as a myeloid oncogene that recruits the E3 ubiquitin ligase COP1 to C/EBPα and interacts with MEK1 to enhance extracellular signal-regulated kinase (ERK) phosphorylation. A close genetic effect of Trib1 on Hoxa9 has been observed in myeloid leukemogenesis, where Trib1 overexpression significantly accelerates Hoxa9-induced leukemia onset. However, the mechanism underlying how Trib1 functionally modulates Hoxa9 transcription activity is unclear. Herein, we provide evidence that Trib1 modulates Hoxa9-associated super-enhancers. Chromatin immunoprecipitation sequencing analysis identified increased histone H3K27Ac signals at super-enhancers of the Erg, Spns2, Rgl1, and Pik3cd loci, as well as increased messenger RNA expression of these genes. Modification of super-enhancer activity was mostly achieved via the degradation of C/EBPα p42 by Trib1, with a slight contribution from the MEK/ERK pathway. Silencing of Erg abrogated the growth advantage acquired by Trib1 overexpression, indicating that Erg is a critical downstream target of the Trib1/Hoxa9 axis. Moreover, treatment of acute myeloid leukemia (AML) cells with the BRD4 inhibitor JQ1 showed growth inhibition in a Trib1/Erg-dependent manner both in vitro and in vivo. Upregulation of ERG by TRIB1 was also observed in human AML cell lines, suggesting that Trib1 is a potential therapeutic target of Hoxa9-associated AML. Taken together, our study demonstrates a novel mechanism by which Trib1 modulates chromatin and Hoxa9-driven transcription in myeloid leukemogenesis.
| S-EPMC7976434 | biostudies-literature
Project description:The pseudokinase Trib1 functions as a myeloid oncogene that recruits E3 ubiquitin ligase COP1 to C/EBPa, and interacts with MEK1 to enhance ERK phosphorylation. Close genetic interaction between Trib1 and Hoxa9 has been observed in myeloid leukemogenesis as Trib1 overexpression significantly accelerates Hoxa9-induced leukemia onset. Yet the mechanism how Trib1 functionally modulates Hoxa9 transcription activity is unclear. Here we provide evidence that Trib1 modulates Hoxa9-associated super-enhancers. ChIP-seq analyses identified increased Histone H3K27Ac signals at the super-enhancers such as Erg, Aff3, Spns2 and Coro2 loci, as well as increased mRNA expression of these genes. The modification of super-enhancer activities is mostly achieved by degradation of C/EBPa by Trib1 and the MEK/ERK pathway only slightly contributes to the activities. Silencing of Erg abrogates the growth advantage acquired by Trib1 overexpression, indicating that Erg is a critical downstream target of the Trib1/Hoxa9 axis. Moreover, treatment of AML cells with the BRD4 inhibitor JQ1 showed growth inhibition in the Trib1/Erg-dependent manner. Upregulation of ERG by TRIB1 was also observed in human AML cell lines, suggesting that Trib1 is a potential target of Hoxa9-associated AML. We used microarrays to detail the global program of gene expression in mouse AML
2020-10-21 | GSE139641 | GEO
Project description:The pseudokinase Trib1 functions as a myeloid oncogene that recruits E3 ubiquitin ligase COP1 to C/EBP, and interacts with MEK1 to enhance ERK phosphorylation. Close genetic interaction between Trib1 and Hoxa9 has been observed in myeloid leukemogenesis as Trib1 overexpression significantly accelerates Hoxa9-induced leukemia onset. Yet the mechanism how Trib1 functionally modulates Hoxa9 transcription activity is unclear. Here we provide evidence that Trib1 modulates Hoxa9-associated super-enhancers. ChIP-seq analyses identified increased Histone H3K27Ac signals at the super-enhancers such as Erg, Aff3, Spns2 and Coro2 loci, as well as increased mRNA expression of these genes. The modification of super-enhancer activities is mostly achieved by degradation of C/EBP by Trib1 and the MEK/ERK pathway only slightly contributes to the activities. Silencing of Erg abrogates the growth advantage acquired by Trib1 overexpression, indicating that Erg is a critical downstream target of the Trib1/Hoxa9 axis. Moreover, treatment of AML cells with the BRD4 inhibitor JQ1 showed growth inhibition in the Trib1/Erg-dependent manner. Upregulation of ERG by TRIB1 was also observed in human AML cell lines, suggesting that Trib1 is a potential target of Hoxa9-associated AML.
2020-10-21 | GSE140313 | GEO
Project description:Trib1 promotes acute myeloid leukemia progression by modulating transcriptional programs of Hoxa9
| PRJNA589270 | ENA
Project description:Trib1 promotes acute myeloid leukemia progression by modulating transcriptional programs of Hoxa9 [array]
| PRJNA586761 | ENA
Project description:Trib1 promotes acute myeloid leukemia progression by modulating transcriptional programs of Hoxa9 [ChIP-seq]
| PRJNA589286 | ENA
Project description:Mass Spectrometry analysis of the interactome of the oncoprotein NUP98-HOXA9
2017-07-10 | PXD001828 | Pride
Project description:C/EBPα is a key transcription factor regulating myeloid differentiation and leukemogenesis. The Trib1-COP1 complex is an E3 ubiquitin ligase that targets C/EBPα for degradation, and its overexpression specifically induces acute myeloid leukemia (AML). Here we show that myeloid leukemia factor 1 (MLF1) stabilizes C/EBPα protein levels by inhibiting the ligase activity of the Trib1-COP1 complex. MLF1 directly interacts with COP1 in the nucleus and interferes with the formation of the Trib1-COP1 complex, thereby blocking its ability to polyubiquitinate C/EBPα for degradation. MLF1 overexpression suppressed the Trib1-induced growth advantage in a murine bone marrow (BM) culture and Trib1-induced AML development in BM-transplanted mouse models. MLF1 was expressed in hematopoietic stem cells and myeloid progenitors (common myeloid progenitors and granulocyte-macrophage progenitors) in normal hematopoiesis, which is consistent with the distribution of C/EBPα. An MLF1 deficiency conferred a more immature phenotype on Trib1-induced AML development. A higher expression ratio of Trib1 to MLF1 was a key determinant for AML development in mouse models, which was also confirmed in human patient samples with acute leukemia. These results indicate that MLF1 is a positive regulator that is critical for C/EBPα stability in the early phases of hematopoiesis and leukemogenesis.
| S-EPMC5728337 | biostudies-literature
Project description:BackgroundAcute myeloid leukemia (AML) is a myeloid neoplasm accounts for 7.6% of hematopoietic malignancies. AML is a complex disease, and understanding its pathophysiology is contributing to the improvement in the treatment and prognosis of AML. In this study, we assessed the expression profile and molecular functions of CCAAT enhancer binding protein gamma (CEBPG), a gene implicated in myeloid differentiation and AML progression.MethodsshRNA mediated gene interference was used to down-regulate the expression of CEBPG in AML cell lines, and knockdown efficiency was detected by RT-qPCR and western blotting. The effect of knockdown on the growth of AML cell lines was evaluated by CCK-8. Western blotting was used to detect PARP cleavage, and flow cytometry were used to determine the effect of knockdown on apoptosis of AML cells. Genes and pathways affected by knockdown of CEBPG were identified by gene expression analysis using RNA-seq. One of the genes affected by knockdown of CEBPG was Eukaryotic translation initiation factor 4E binding protein 1 (EIF4EBP1), a known repressor of translation. Knockdown of EIF4EBP1 was used to assess its potential role in AML progression downstream of CEBPG.ResultsWe explored the ChIP-Seq data of AML cell lines and non-AML hematopoietic cells, and found CEBPG was activated through its distal enhancer in AML cell lines. Using the public transcriptomic dataset, the Cancer Cell Line Encyclopedia (CCLE) and western blotting, we also found CEBPG was overexpressed in AML. Moreover, we observed that CEBPG promotes AML cell proliferation by activating EIF4EBP1, thus contributing to the progression of AML. These findings indicate that CEBPG could act as a potential therapeutic target for AML patients.ConclusionIn summary, we systematically explored the molecular characteristics of CEBPG in AML and identified CEBPG as a potential therapeutic target for AML patients. Our findings provide novel insights into the pathophysiology of AML and indicate a key role for CEBPG in promoting AML progression.
| S-EPMC8574011 | biostudies-literature
Project description:Acute myeloid leukemia (AML) is an aggressive hematological malignancy with high relapse/refractory rate. Genetic and epigenetic abnormalities are driving factors for leukemogenesis. RUNX1 and RUNX2 from the Runt-related transcription factor (RUNX) family played important roles in AML pathogenesis. However, the relationship between RUNX3 and AML remains unclear. Here, we found that RUNX3 was a super-enhancer-associated gene and highly expressed in AML cells. The Cancer Genome Atlas (TCGA) database showed high expression of RUNX3 correlated with poor prognosis of AML patients. We observed that Runx3 knockdown significantly inhibited leukemia progression by inducing DNA damage to enhance apoptosis in murine AML cells. By chromatin immunoprecipitation sequencing (ChIP-seq) analysis, we discovered that RUNX3 in AML cells mainly bound more genes involved in DNA-damage repair and antiapoptosis pathways compared to that in normal bone marrow cells. Runx3 knockdown obviously inhibited the expression of these genes in AML cells. Overall, we identified RUNX3 as an oncogene overexpressed in AML cells, and Runx3 knockdown suppressed AML progression by inducing DNA damage and apoptosis.
| S-EPMC8549545 | biostudies-literature