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Nucleophosmin 1 regulates H3K79me2 levels and peri-nucleolar heterochromatin organization through interaction with the methyltransferase DOT1L [ChIP-seq]

ABSTRACT: The histone methyltransferase DOT1L catalyzes methylation of H3K79 and it is highly conserved in mammals. DOT1L plays a functional role in several biological processes including cell cycle regulation, DNA repair, RNA splicing and gene expression, suggesting a complex role in chromatin organization and regulation. Such a remarkable range of functions performed by DOT1l can be the result, at least partially, of its interaction with different proteins and presence in different complexes. Here, we characterized the interaction of DOT1L with the nucleolar protein NPM1 and the impact of the DOT1L/NPM1 complex on nucleoli organization and activity. We show that i) DOT1L interacts preferentially with monomeric NPM1 in the nucleus; ii) DOT1L interaction with NPM1 is key to maintain their protein homeostasis; iii) NPM1 depletion results in H3K79me2 upregulation at chromatin remodeling genes; iv) DOT1L/NPM1 complex preserved peri-nucleolar heterochromatin organization via epigenetic mechanisms. Our findings unravel the molecular mechanisms employed by the DOT1L/NPM1 complex to maintain heterochromatin organization around the nucleoli and shed light on one aspect of the complex role of DOT1L in chromatin dynamics.

ORGANISM(S): Mus musculus

PROVIDER: GSE223361 | GEO | 2024/01/01

REPOSITORIES: GEO

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Nucleophosmin 1 regulates H3K79me2 levels and peri-nucleolar heterochromatin organization through interaction with the methyltransferase DOT1L [RNA-seq]

Project description:The histone methyltransferase DOT1L catalyzes methylation of H3K79 and it is highly conserved in mammals. DOT1L plays a functional role in several biological processes including cell cycle regulation, DNA repair, RNA splicing and gene expression, suggesting a complex role in chromatin organization and regulation. Such a remarkable range of functions performed by DOT1L can be the result, at least partially, of its interaction with a plethora of proteins and presence in different complexes. Here, we characterized the cooperation of DOT1L with the nucleolar protein NPM1 and the impact of both proteins on peri-nucleolar heterochromatin activity. We show that i) DOT1L interacts preferentially with monomeric NPM1 in the nucleus; ii) DOT1L acts in concert with NPM1 to maintain each other’s protein homeostasis; iii) NPM1 depletion results in H3K79me2 upregulation at chromatin remodeling genes and transcriptional activation of Ezh2; iv) DOT1L and NPM1 preserved DNA satellite expression at peri-nucleolar heterochromatin via epigenetic mechanisms dependent on H3K27me3. Our findings give insights into molecular mechanisms employed by DOT1L and NPM1 to regulate heterochromatin activities around the nucleoli and shed light on one aspect of the complex role of both proteins in chromatin dynamics.

2024-01-01 | GSE223362 | GEO

DOT1L regulates pericentromeric heterochromatin

Project description:Many repetitive DNA elements are packaged in heterochromatin, but depend on occasional transcription to maintain long-term silencing. The factors that promote transcription of repeat elements in heterochromatin are largely unknown. Here, we show that DOT1L, a histone methyltransferase that modifies lysine 79 of histone H3 (H3K79), is required for transcription of major satellite repeats to maintain pericentromeric heterochromatin (PCH), and that this function is essential for preimplantation development. DOT1L is a transcriptional activator at single-copy genes but does not have a known role in repeat element transcription. We show that H3K79me3 is specifically enriched at repetitive elements, that loss of DOT1L compromises pericentromeric major satellite transcription, and that this function depends on interaction between DOT1L and the chromatin remodeler SMARCA5. DOT1L inhibition causes chromosome breaks and cell cycle defects, and leads to embryonic lethality. Together, our findings uncover a vital new role for DOT1L in transcriptional activation of heterochromatic repeats.

2023-05-26 | PXD028824 | Pride

Nucleophosmin sustains WNT-driven cell proliferation and tumor initiation in vivo

Project description:Nucleophosmin (NPM1) is a nucleolar protein frequently overexpressed in many solid tumours with little known about its functional role to support carcinogenesis. Here, we identify Npm1 as a commonly upregulated gene following Apc loss in highly proliferative tissues, and high expression correlates with increased proliferation in CRC patients. We show that NPM1 is dispensable for adult epithelial tissue homeostasis, however, it has a profound effect on WNT-driven intestinal and liver tumourigenesis, leading to reduced proliferation and extension of survival. Mechanistically, NPM1 depletion triggers integrated stress response (ISR) and p53 pathway activation. P53 deletion, or inhibition of the ISR effects, rescue proliferation following NPM1 loss. Overall, our results demonstrate that NPM1 supports WNT-driven cell proliferation and tumour initiation by attenuating p53 pathway activation or induction of ISR. Being dispensable for homeostasis, NPM1 presents as a promising target for cancer therapy in WNT-driven tumours with functional p53, including difficult to treat KRAS-mutant CRC and hepatic cancers.

2024-02-15 | GSE249958 | GEO

ChIP-seq analysis about Dot1l and Npm1 samples

Project description:To identify whether Dot1l or Npm1 were enriched in MERVL directly, we performed Dot1l and Npm1 ChIP-seq in wildtype ESCs. We conclude that Dot1l and Npm1 binding were enriched on MERVL-int region, suggesting a direct regulatory role of Dot1l and Npm1 on MERVL expression.

2023-07-18 | GSE201848 | GEO

Targeting Chromatin Regulators Inhibits Leukemogenic Gene Expression in NPM1 Mutant Leukemia

Project description:Homeobox (HOX) proteins and the receptor tyrosine kinase FLT3 are frequently highly expressed and mutated in acute myeloid leukemia (AML). Aberrant HOX expression is found in nearly all AMLs that harbor a mutation in the Nucleophosmin (NPM1) gene, and FLT3 is concomitantly mutated in approximately 60% of these cases. Little is known how mutant NPM1 (NPM1mut) cells maintain aberrant gene expression. Here, we demonstrate that the histone modifiers MLL1 and DOT1L control HOX and FLT3 expression and differentiation in NPM1mut AML. Using a CRISPR-Cas9 genome editing domain screen, we show NPM1mut AML to be exceptionally dependent on the menin binding site in MLL1. Pharmacological small-molecule inhibition of the menin-MLL protein interaction had profound anti-leukemic activity in human and murine models of NPM1mut AML in vitro and in vivo. Combined pharmacological inhibition of menin-MLL and DOT1L resulted in dramatic suppression of HOX and FLT3 expression, induction of differentiation, and superior activity against NPM1mut leukemia. Together, MLL1 and DOT1L are chromatin regulators that control HOX, MEIS1 and FLT3 expression and are therapeutic targets in NPM1mut AML. Combinatorial small-molecule inhibition has synergistic on target activity and constitutes a novel therapeutic concept for this common AML subtype. RNA sequencing data of the human AML cell lines OCI-AML2 and OCI-AML3 comparing EPZ004777 [10ÂµM] drug treatment versus DMSO vehicle control; experiments performed in biological triplicates.

2016-08-22 | E-GEOD-85107 | biostudies-arrayexpress

Caspase-2 is essential for proliferation and self-renewal of nucleophosmin-mutated acute myeloid leukemia

Project description:Mutation in nucleophosmin (NPM1) causes relocalization of this normally nucleolar protein to the cytoplasm (NPM1c+). Despite NPM1 mutation being the most common driver mutation in cytogenetically normal adult acute myeloid leukemia (AML), the mechanisms of NPM1c+-induced leukemogenesis remain unclear. Caspase-2 is a pro-apoptotic protein activated by NPM1 in the nucleolus. Here, we show that caspase-2 is also activated by NPM1c+ in the cytoplasm and DNA damage-induced apoptosis is caspase-2-dependent in NPM1c+ but not in NPM1wt AML cells. Strikingly, in NPM1c+ cells, caspase-2 loss results in profound cell cycle arrest, differentiation, and down-regulation of stem cell pathways that regulate pluripotency including impairment in the AKT/mTORC1 and Wnt signaling pathways, and inhibition of Rictor cleavage. In contrast, there were minimal differences in proliferation, differentiation, or the transcriptional profile of NPM1wt cells lacking caspase-2. Our results show that caspase-2 is essential for proliferation and self-renewal of AML cells expressing mutated NPM1. This study demonstrates that caspase-2 is a major effector of NPM1c+ function.

2024-04-17 | GSE249545 | GEO

Multilineage dysplasia and AML with mutated nucleophosmin

Project description:Multilineage dysplasia (MLD) has no impact on biological, clinico-pathological and prognostic features of AML with mutated nucleophosmin (NPM1) NPM1-mutated AML is a provisional entity in the WHO-2008 classification of myeloid neoplasms. The significance of concomitant multilineage dysplasia (MLD) in NPM1-mutated AML is unclear. Thus, in the WHO-2008 classification, NPM1-mutated AML with MLD is classified as AML with myelodysplasia(MD)-related changes. We evaluated the MLD impact in 378 NPM1-mutated AML patients. MLD was found in about 25% cases. Except for a lower WBC and FLT3-ITD incidence in MLD+ group, no significant differences were observed in age, sex, cytogenetics and FLT3-TKD between NPM1-mutated AML with and without MLD. Notably, NPM1-mutated AML with/without MLD showed overlapping immunophenotype (CD34-negativity) and GEP (CD34 downregulation and HOX genes upregulation). Moreover, OS and EFS did not differ among NPM1-mutated AML patients, independently of whether they carried or not MLD, the NPM1-mutated/FLT3-ITD negative cases showing the better prognosis. Lack of MLD impact on survival was confirmed by multivariate analysis that highlighted FLT3-ITD as the most significant prognostic parameter in NPM1-mutated AML. Our findings indicate that NPM1 mutations rather than MLD dictate the distinctive features of NPM1-mutated AML. Thus, irrespective of MLD, NPM1-mutated AML should be considered as one disease entity clearly distinct from AML with MD-related changes. These findings have important diagnostic and prognostic implications in AML. All bone marrow samples were obtained from untreated patients at the time of diagnosis. Cells used for microarray analysis were collected from the purified fraction of mononuclear cells after Ficoll density centrifugation. 48 samples

2010-07-30 | E-GEOD-18018 | biostudies-arrayexpress

Multilineage dysplasia and AML with mutated nucleophosmin

2010-07-01 | GSE18018 | GEO

HA-GABARAPL1 immunoprecipitation with siRNA-mediated NPM1 depletion

Project description:The nucleolar scaffold protein NPM1 acts as a multifunctional regulator of cellular homeostasis, genome integrity, and stress response. We and others show that NPM1 is also involved in regulation of the autophagic pathway. As NPM1 binds to members of the GABARAP protein family, important for autophagy, we anticipate that this interaction is important for the role of NPM1 in autophagy. In order to identify NPM1-dependent GABARAPL1 interactors we performed HA-GABARAPL1 immunoprecipitation with siRNA-mediated NPM1 depletion.

2023-10-28 | PXD040220 | Pride

Maintenance of nucleolar homeostasis by CBX4 alleviates senescence and osteoarthritis

Project description:CBX4, a component of polycomb repressive complex 1 (PRC1), plays important roles in the maintenance of cell identity and organ development through epigenetic silencing. However, whether CBX4 regulates the homeostasis of human stem cells remains unclear. Here, we demonstrate that CBX4 counteracts human mesenchymal stem cell (hMSC) aging via the maintenance of nucleolar homeostasis. CBX4 protein is decreased in aged hMSCs, and targeted CBX4 knockout in young hMSCs results in destabilized nucleolar heterochromatin, increased ribosome biogenesis and protein translation, and accelerated cellular senescence. CBX4 maintains nucleolar homeostasis by recruiting nucleolar protein fibrillarin and heterochromatin organization associated protein KAP1 at nucleolar rDNA, limiting the excessive expression of rRNAs. Importantly, overexpression of CBX4 alleviates physiological hMSC aging and attenuates the development of posttraumatic osteoarthritis in mice. Taken together, our findings reveal a novel role of CBX4 in counteracting senescence by maintaining nucleolar homeostasis, providing a potential therapeutic target for aging-associated disorders.

2019-01-19 | GSE125320 | GEO

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