Project description:Abarrent transcriptional regulation is one of hallmarks of leukemia. GFI1 is a transcriptional regulator with context-dependent roles in hematopoiesis and leukemogenesis. Reduced or loss of GFI1 expression has been reported in myeloid malignancies, while high GFI1 expression has been observed in AML1-ETO-positive acute myeloid leukemia (AML) and acute lymphoid leukemia, but without clear roles defined for GFI1 in APL pathogenesis. We here performed ChIP-seq analysis using antibodies against GFI1 and identified genome-wide binding site of GFI1 in NB4 cells.
Project description:The zinc finger transcription factor growth-factor-independent-1 (Gfi1) has been involved in various cellular differentiation processes. Gfi1 acts as a transcriptional repressor and splicing control factor upon binding to cognate binding sites in regulatory elements of its target genes. Here, we report that Gfi1-deficient mice develop autoimmunity. Gfi1-deficient peripheral B-cells show a hyperproliferative phenotype, leading to expansion of plasma cells, increased levels of nuclear autoantibodies, and immunoglobulin deposition in brain and kidneys. Dysregulation of multiple transcription factors and cell-cycle control elements may contribute to B-cell dependent autoimmunity. Gfi1 thus emerges as a novel master-regulator restricting autoimmunity. Experiment Overall Design: Splenic B220+CD19+ CD138- B cells of 4 week old Gfi1+/+ and Gfi1-/- mice were isolated and RNA was extracted from one sample per group and microarray analysis was performed.
Project description:The zinc finger transcription factor growth-factor-independent-1 (Gfi1) has been involved in various cellular differentiation processes. Gfi1 acts as a transcriptional repressor and splicing control factor upon binding to cognate binding sites in regulatory elements of its target genes. Here, we report that Gfi1-deficient mice develop autoimmunity. Gfi1-deficient peripheral B-cells show a hyperproliferative phenotype, leading to expansion of plasma cells, increased levels of nuclear autoantibodies, and immunoglobulin deposition in brain and kidneys. Dysregulation of multiple transcription factors and cell-cycle control elements may contribute to B-cell dependent autoimmunity. Gfi1 thus emerges as a novel master-regulator restricting autoimmunity.
Project description:GFI1 is a transcriptional repressor protein that plays an essential role in HSCs development, lymphoid and myeloid differentiation and Acute Myeloid Leukaemic (AML) pathogenesis. Low expression levels of GFI1 is associated with a poor prognosis in AML development. In addition, a single nucleotide polymorphism (SNP) variant of GFI1 results in the generation of GFI1 protein with asparagine (N) instead of serine (S) at the 36th amino acid position, known as GFI136N. Expression of the GFI1-36N allele leads as well to poor prognosis and promotes AML development. In this study, we demonstrated with the help of RNAseq transcriptomic analysis that the presence of GFI1-36N is associated with increased frequency of chromosomal aberrations and mutational burden in murine and human AML cells. In particular, GFI1-36N modulates DNA repair pathways, O6-methylguanine-DNA-methyltransferase (MGMT)-mediated repair and homologous recombination repair (HR). Mechanistically, GFI1-36N exhibits impaired binding to Ndrg1 promoter element compared to GFI1-36S (wild type), causing decreased NDRG1 levels, consequently leading to suppression of MGMT expression, imprinted at the transcriptome and proteome, thus leaving the AML cells vulnerable to DNA damaging agents. Furthermore, we showed that a low expression level of GFI1 in leukemic cells is associated with high OXPHOS and enhanced glutamine metabolism. However, we hypothesise that the observed metabolic phenotype is mediated through FOXO1 protein. RNAseq transcriptomic analysis revealed higher Foxo1 mRNA expression levels with lower GFI1 expression, providing the first hint of Foxo1 as a potential target gene of GFI1 protein. The mRNA and protein levels of high Foxo1 with reduced GFI1 expression was confirmed by RT-PCR and western blot, respectively. In addition, CHIPseq and ATACseq analysis further proved that Foxo1 is a potential target gene of GFI1. In summary, we show that GFI1 plays a role during DNA repair and metabolism and thus provides critical insights into a novel therapeutic option for AML patients carrying the GFI1-36N variant or having a low expression level of GFI1.
Project description:Gfi1 is a transcription factor broadly participate in differentiation of immune cells and loss of Gfi1 could result in severe neutrophil deficiency. To gain insight into the consequences of lack of Gfi1 on a genome-wide level, we conducted genome-wide transcriptome profiling in Wide-type (WT) and Gfi1–/– Raw264.7 macrophage cells using Affymetrix Mouse 3’ IVT microarrays
Project description:Illumina High-Throughput ChIP Sequencing profiling was performed using the H3K9K14ac antibody in NB4 cells treated with the compounds ATRA, MS-275,MC2392 (a hybrid molecule of ATRA with a 2-aminoanilide tail of the HDAC inhibitor MS-275) or solvent, DMSO. We find that MC2392 induces changes in H3 acetylation at a small subset of PML-RARα binding sites but also in regions not regulated by ATRA. Moreover, MC2392 alters expression of a number of stress-responsive and apoptotic genes.
Project description:ChIP-Seq Analysis of H3K9Ac in pairs of mouse and human samples carrying either the Gfi136S or the GFi136N variants. The objective of the study was to identify the changes in H3K9 acetylation at gene promoters that occur in samples expressing the 36N variant of the Gfi1 gene. 3 pairs of bone-marrow AML samples were obtained from mice where 1 mouse in each pair was homozygous for Gfi136S and 1 heterozygous for Gfi136N, or homozygous for 36N in one case. 2 pairs of AML samples were obtained from human patients were 1 patient was homozygous for Gfi1 36S and one was heterozygous for Gfi1 36N. H3 and H3K9Ac ChIP-Seq was carried out on each sample.
Project description:Pharmacologic inhibition of LSD1 induces molecular and morphologic differentiation of blast cells in acute myeloid leukaemia (AML) patients harboring MLL gene translocations. In addition to its demethylase activity, LSD1 has a critical scaffolding function at genomic sites occupied by the SNAG domain transcription repressor GFI1. Importantly, inhibitors block both enzymatic and scaffolding activities, in the latter case by disrupting the protein:protein interaction of GFI1 with LSD1. To explore the wider consequences of LSD1 inhibition on the LSD1 protein complex we made use of mass spectrometry approaches. We discovered that the interaction of the HMG-box protein HMG20B with LSD1 was also disrupted by LSD1 inhibition. Downstream investigations revealed that HMG20B is colocated on chromatin genome-wide with GFI1 and LSD1; the strongest HMG20B binding colocates with the strongest GFI1 and LSD1 binding. Functional assays demonstrated that HMG20B depletion induces leukaemia cell differentiation and further revealed that HMG20B is required for the transcription repressor activity of GFI1 through stabilizing the interaction on chromatin of LSD1 with GFI1. Interaction of HMG20B with LSD1 is through its coiled-coil domain. Thus, HMG20B is a critical component of the GFI1:LSD1 transcription repressor complex which contributes to leukaemia cell differentiation block.