The role of MLF1 on accessible chromatin in AC16 cell line
Ontology highlight
ABSTRACT: Previous studies found that MLF1 mRNA levels tended to decline in aging hearts. Functional studies found that knockdown of MLF1 ameliorated the drug-induced cellular senescence phenotype. Here, we apply transcriptomics to explore the underlying molecular mechanisms.
Project description:Previous studies found that MLF1 mRNA levels tended to decline in aging hearts. Functional studies found that knockdown of MLF1 ameliorated the drug-induced cellular senescence phenotype. Here, we apply transcriptomics to explore the underlying molecular mechanisms.
Project description:Previous studies found that MLF1 mRNA levels tended to decline in aging hearts. Functional studies found that knockdown of MLF1 ameliorated the drug-induced cellular senescence phenotype. Here, we apply CUT&Tag to explore the underlying molecular mechanisms.
Project description:Functional studies found that knockdown of EP300 ameliorated the drug-induced cellular senescence phenotype. Here, we apply transcriptomics to explore the underlying molecular mechanisms.
Project description:Nucleophosmin (NPM1) is either frequently mutated or subjected to chromosomal translocation in acute myeloid leukemia (AML). NPM protein is primarily located in the nucleus, but the recurrent NPMc+ mutation is characterized by cytoplasmic localization and leukemogenic properties. Similarly, the NPM-MLF1 translocation product favors the partial cytoplasmic retention of NPM. Regardless of their common cellular distribution, NPM-MLF1 malignancies engender different effects on hematopoiesis compared to NPMc+ counterparts, highlighting possible aberrant nuclear function(s) of NPM in NPMc+ AML. We performed a proteomics analysis and found that NPM and NPM-MLF1 interact with chromatin remodeling complexes of the ISWI family, as well as with NuRD and P/BAF complexes. Accordingly, NPM and NPM-MLF1 are recruited to transcriptionally active or repressed genes along with NuRD and P/BAF elements. Although the overall gene expression program in NPM knockdown cells is similar to that resulting from NPMc+ and is consistent with loss of nuclear function of NPM, NPM-MLF1 expression differentially altered gene transcription regulated by NPM. The abnormal gene regulation imposed by NPM-MLF1 is characterized by enhanced recruitment of NuRD to gene regulatory regions. Thus, different mechanisms orchestrate the deregulation of NPM function in NPMc+- versus NPM1-MLF1-associated leukemia.
Project description:Nucleophosmin (NPM1) is either frequently mutated or subjected to chromosomal translocation in acute myeloid leukemia (AML). NPM protein is primarily located in the nucleus, but the recurrent NPMc+ mutation is characterized by cytoplasmic localization and leukemogenic properties. Similarly, the NPM-MLF1 translocation product favors the partial cytoplasmic retention of NPM. Regardless of their common cellular distribution, NPM-MLF1 malignancies engender different effects on hematopoiesis compared to NPMc+ counterparts, highlighting possible aberrant nuclear function(s) of NPM in NPMc+ and NPM-MLF1 AML. We performed a proteomics analysis and found that NPM and NPM-MLF1 interact with chromatin remodeling complexes of the ISWI family, as well as with NuRD and P/BAF complexes. Accordingly, NPM and NPM-MLF1 are recruited to transcriptionally active or repressed genes along with NuRD and P/BAF elements. Although the overall gene expression program in NPM knockdown cells is similar to that resulting from NPMc+ and is consistent with loss of nuclear function of NPM, NPM-MLF1 expression differentially altered gene transcription regulated by NPM. The abnormal gene regulation imposed by NPM-MLF1 is characterized by enhanced recruitment of NuRD to gene regulatory regions. Thus, different mechanisms orchestrate the deregulation of NPM function in NPMc+ -versus NPM1-MLF1- associated leukemia.
Project description:Myeloid leukemia factor 1 (Mlf1) was identified as a proto-oncoprotein that affects hematopoietic differentiation in humans. However, its cellular function remains elusive, spanning roles from cell cycle regulation to modulation of protein aggregate formation and participation in ciliogenesis. Given that structurally conserved homologs of Mlf1 can be found across the eukaryotic tree of life, we decided to characterize its cellular role underlying this phenotypic pleiotropy. Using a model of the unicellular eukaryote Giardia intestinalis, we demonstrate that its Mlf1 homolog (GiMlf) mainly localizes to two types of cytosolic foci: microtubule nucleation zones, where it interacts with Hsp40, and ubiquitin-rich, membraneless compartments, found adjacent to mitochondrion-related organelles known as mitosomes, containing the 26S proteasome regulatory subunit 4. Upon cellular stress, GiMlf either relocates to the affected compartment or disperses across the cytoplasm, subsequently accumulating into enlarged foci during the recovery phase. In vitro assays suggest that GiMlf can be recruited to membranes through its affinity for signaling phospholipids. Importantly, cytosolic foci diminish in the gimlf knockout strain, which exhibits extensive proteomic changes indicative of compromised proteostasis. Consistent with data from other cellular systems, we propose that Mlf acts in the response to proteotoxic stress by mediating the formation of function-specific foci for protein folding and degradation.
Project description:Nucleophosmin (NPM1) is a nucleolar protein and one of the most frequently mutated genes in acute myeloid leukemia (AML). In addition to the commonly detected frameshift mutations in exon12 (NPM1c), previous studies have identified NPM1 gene rearrangements leading to the expression of NPM1-fusion proteins in pediatric AML. However, whether the NPM1-fusions are indeed oncogenic and how the NPM1-fusions cause AML have been largely unknown. In this study, we investigated the subcellular localization and leukemogenic potential of two rare NPM1-fusion proteins, NPM1-MLF1 and NPM1-CCDC28A. NPM1-MLF1 is present in both the nucleus and cytoplasm and occasionally induces AML in the mouse transplantation assay (2/12). NPM1-CCDC28A localizes predominantly to the cytoplasm, immortalizes mouse bone marrow cells in vitro and efficiently (5/6) induces AML in vivo. Mechanistically, both NPM1-fusions bind to the HOX gene cluster and, like NPM1c, cause aberrant upregulation of HOX genes in cooperation with XPO1. The XPO1 inhibitor selinexor suppressed HOX activation and colony formation driven by the NPM1-fusions. Thus, our study provides experimental evidence that both NPM1-MLF1 and NPM1-CCDC28A are oncogenes with functions similar to NPM1c. Inhibition of XPO1 may be a promising strategy for the NPM1-rearranged AML.
Project description:Nucleophosmin (NPM1) is a nucleolar protein and one of the most frequently mutated genes in acute myeloid leukemia (AML). In addition to the commonly detected frameshift mutations in exon12 (NPM1c), previous studies have identified NPM1 gene rearrangements leading to the expression of NPM1-fusion proteins in pediatric AML. However, whether the NPM1-fusions are indeed oncogenic and how the NPM1-fusions cause AML have been largely unknown. In this study, we investigated the subcellular localization and leukemogenic potential of two rare NPM1-fusion proteins, NPM1-MLF1 and NPM1-CCDC28A. NPM1-MLF1 is present in both the nucleus and cytoplasm and occasionally induces AML in the mouse transplantation assay (2/12). NPM1-CCDC28A localizes predominantly to the cytoplasm, immortalizes mouse bone marrow cells in vitro and efficiently (5/6) induces AML in vivo. Mechanistically, both NPM1-fusions bind to the HOX gene cluster and, like NPM1c, cause aberrant upregulation of HOX genes in cooperation with XPO1. The XPO1 inhibitor selinexor suppressed HOX activation and colony formation driven by the NPM1-fusions. Thus, our study provides experimental evidence that both NPM1-MLF1 and NPM1-CCDC28A are oncogenes with functions similar to NPM1c. Inhibition of XPO1 may be a promising strategy for the NPM1-rearranged AML.