Clonal Haematopoiesis-related Mutant ASXL1 Promotes Atherosclerosis in Mice via Dysregulated Innate Immunity
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PROVIDER: PRJNA1172723 | ENA |
REPOSITORIES: ENA
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Project description:Certain somatic mutations confer a fitness advantage in hematopoietic stem cells, resulting in the clonal expansion of mutant blood cells, known as clonal haematopoiesis (CH). Among the top 3 CH mutations, ASXL1 mutations present the highest risk for developing cardiovascular diseases (CVDs). However, how ASXL1 mutations induce CVDs remains totally elusive. Here we show that haematopoietic cells harbouring C-terminally truncated form of ASXL1 mutant (ASXL1-MT) accelerated development of atherosclerosis in Ldlr–/– mice. Transcriptome analyses of plaque-cells showed inflammatory signatures of monocytes and macrophages expressing ASXL1-MT. Mechanistically, wild-type ASXL1 inhibited innate immune signalling through the inhibition of IRAK1-TAK1 interaction in the cytoplasm, indicating an unexpected non-epigenetic role of ASXL1. In contrast, ASXL1-MT lost this regulatory function, leading to NF-κB activation. Intriguingly, IRAK1/4 inhibition decreased inflammatory monocytes and atherosclerosis driven by ASXL1-MT. The present work connects ASXL1 mutations with inflammation and CVDs, giving a clue to prevent CVDs in ASXL1-CH.
2024-10-25 | GSE279450 | GEO
Project description:Certain somatic mutations confer a fitness advantage in hematopoietic stem cells, resulting in the clonal expansion of mutant blood cells, known as clonal haematopoiesis (CH). Among the top 3 CH mutations, ASXL1 mutations present the highest risk for developing cardiovascular diseases (CVDs). However, how ASXL1 mutations induce CVDs remains totally elusive. Here we show that haematopoietic cells harbouring C-terminally truncated form of ASXL1 mutant (ASXL1-MT) accelerated development of atherosclerosis in Ldlr–/– mice. Transcriptome analyses of plaque-cells showed inflammatory signatures of monocytes and macrophages expressing ASXL1-MT. Mechanistically, wild-type ASXL1 inhibited innate immune signalling through the inhibition of IRAK1-TAK1 interaction in the cytoplasm, indicating an unexpected non-epigenetic role of ASXL1. In contrast, ASXL1-MT lost this regulatory function, leading to NF-κB activation. Intriguingly, IRAK1/4 inhibition decreased inflammatory monocytes and atherosclerosis driven by ASXL1-MT. The present work connects ASXL1 mutations with inflammation and CVDs, giving a clue to prevent CVDs in ASXL1-CH.
2024-10-25 | GSE279601 | GEO
Project description:Clonal Haematopoiesis-related Mutant ASXL1 Promotes Atherosclerosis in Mice via Dysregulated Innate Immunity [scRNA-seq]
| PRJNA1173577 | ENA
Project description:Somatic mutations of ASXL1 are frequently detected in age-related clonal hematopoiesis (CH). However, how ASXL1 mutations drive CH remains elusive. Using knockin (KI) mice expressing a C-terminally truncated form of ASXL1-mutant (ASXL1-MT), we examined the influence of ASXL1-MT on physiological aging in hematopoietic stem cells (HSCs). HSCs expressing ASXL1-MT display competitive disadvantage after transplantation. Nevertheless, in genetic mosaic mouse model, they acquire clonal advantage during aging, recapitulating CH in humans. Mechanistically, ASXL1-MT cooperates with BAP1 to deubiquitinate and activate AKT. Overactive Akt/mTOR signaling induced by ASXL1-MT results in aberrant proliferation and dysfunction of HSCs associated with age-related accumulation of DNA damage. Treatment with an mTOR inhibitor rapamycin ameliorates aberrant expansion of the HSC compartment as well as dysregulated hematopoiesis in aged ASXL1-MT KI mice. Our findings suggest that ASXL1-MT provokes dysfunction of HSCs, whereas it confers clonal advantage on HSCs over time, leading to the development of CH.
2021-02-08 | MSV000086816 | MassIVE
Project description:Clonal haematopoiesis, which is highly prevalent in older individuals, arises from somatic mutations that endow a proliferative advantage to haematopoietic cells. Clonal haematopoiesis increases the risk of myocardial infarction and stroke independently of traditional risk factors1. Among the common genetic variants that give rise to clonal haematopoiesis, the JAK2V617F (JAK2VF) mutation, which increases JAK-STAT signalling, occurs at a younger age and imparts the strongest risk of premature coronary heart disease1,2. Here we show increased proliferation of macrophages and prominent formation of necrotic cores in atherosclerotic lesions in mice that express Jak2VF selectively in macrophages, and in chimeric mice that model clonal haematopoiesis. Deletion of the essential inflammasome components caspase 1 and 11, or of the pyroptosis executioner gasdermin D, reversed these adverse changes. Jak2VF lesions showed increased expression of AIM2, oxidative DNA damage and DNA replication stress, and Aim2 deficiency reduced atherosclerosis. Single-cell RNA sequencing analysis of Jak2VF lesions revealed a landscape that was enriched for inflammatory myeloid cells, which were suppressed by deletion of Gsdmd. Inhibition of the inflammasome product interleukin-1β reduced macrophage proliferation and necrotic formation while increasing the thickness of fibrous caps, indicating that it stabilized plaques. Our findings suggest that increased proliferation and glycolytic metabolism in Jak2VF macrophages lead to DNA replication stress and activation of the AIM2 inflammasome, thereby aggravating atherosclerosis. Precise application of therapies that target interleukin-1β or specific inflammasomes according to clonal haematopoiesis status could substantially reduce cardiovascular risk.
| S-EPMC8038646 | biostudies-literature
Project description:Longitudinal dynamics of clonal haematopoiesis identifies gene-specific fitness effects
| PRJNA812679 | ENA
Project description:Additional Sex Combs Like 1 (ASXL1) is frequently mutated in myeloid malignancies and clonal hematopoiesis of indeterminate potential (CHIP). Although loss of ASXL1 promotes hematopoietic transformation, there is growing evidence that ASXL1 mutations might confer an alteration of function. Here we identify that physiological expression of a C-terminal truncated Asxl1 mutant in vivo using conditional knock-in (KI) results in myeloid skewing, age-dependent anemia, thrombocytosis, and morphologic dysplasia. Although expression of mutant Asxl1 altered the functions of hematopoietic stem cells (HSCs), it maintained their survival in competitive transplantation assays and increased susceptibility to leukemic transformation by co-occurring RUNX1 mutation or viral insertional mutagenesis. KI mice displayed substantial reductions in H3K4me3 and H2AK119Ub without significant reductions in H3K27me3, distinct from the effects of Asxl1 loss. ChIP-seq analysis demonstrated opposing effects of wildtype and mutant Asxl1 on H3K4me3. These findings reveal that ASXL1 mutations confer HSCs with an altered epigenome and increase susceptibility for leukemic transformation, presenting a novel model for CHIP.
2018-02-28 | GSE111067 | GEO
Project description:ASXL1 gene is one of the most frequently mutated genes in malignant myeloid diseases. In patients, ASXL1 mutations are usually heterozygous frameshift or non-sense mutations leading to C-terminal truncation. Here, we generated an endogenous C-terminal truncated Asxl1 mutant in zebrafish which is more comparable to human malignant leukemia patients. Our data showed that at embryonic stage, neutrophil differentiation was explicitly blocked in our mutant. To understand the basis for the impairment of neutrophil differentiation in zebrafish asxl1 mutants, we performed RNA-seq of asxl1 mutants at 3dpf and their littermate controls. Similar with the phenotype we observed, the expression of neutrophil markers were all included in down-regulated genes. Nonetheless, the expression of myeloid progenitor marker and macrophage marker were not impaired in asxl1 mutants. We also found inflammatory cytokine and matrix metalloproteinases were upregulated after mutated asxl1. It suggests that neutrophil deficiency may stimulate the expression of some inflammatory cytokines and enhances the inflammatory responds. Therefore, transcriptome analysis mainly represented the disruption of neutrophil development.
2021-08-04 | GSE142214 | GEO
Project description:RNA sequencing of zebrafish asxl1+/+ and asxl1-/-
| PRJNA596232 | ENA
Project description:ASXL1 is the obligate regulatory subunit of a deubiquitinase complex whose catalytic subunit is BAP1. Heterozygous mutations of ASXL1 that result in premature truncations are frequent in myeloid leukemias and Bohring-Opitz syndrome. Here, we demonstrate that truncated ASXL1 proteins confer enhanced activity on the ASXL1-BAP1 complex. Stable expression of truncated, hyperactive ASXL1-BAP1 complexes in a hematopoietic precursor cell line resulted in global erasure of H2AK119Ub, striking depletion of H3K27me3, selective upregulation of a subset of genes whose promoters bore both H2AK119Ub and H3K4me3, and spontaneous differentiation to the mast cell lineage. These outcomes required the catalytic activity of BAP1, indicating these events were downstream consequences of H2AK119Ub erasure. In bone marrow precursors, truncated ASXL1-BAP1 expression cooperated with TET2 loss-of-function to increase differentiation to the myeloid lineage in vivo. We propose that pathological ASXL1 mutations confer gain-of-function on the ASXL-BAP1 complex. ChIP-Seq for H2AK119Ub, H3K4me3, H3K27me3 on EML cells. RNA-Seq on EML cells expressing ASXL1(1-479)+BAP1 and control.
2015-03-11 | E-GEOD-65555 | biostudies-arrayexpress