Project description:Chromosomal translocation t(8;21) (q22;q22) leading to generation of oncogenic RUNX1-RUNX1T1 (AML1-ETO) fusion is a cytogenetic abnormality observed in about 10% of acute myelogenous leukemia (AML). To uncover somatic mutations that cooperate with t(8;21)-driven leukemia, we performed targeted and whole exome sequencing of newly-diagnosed and relapsed AML samples. We identified high frequency of truncating alterations in ASXL2 along with recurrent mutations of KIT, TET2, MGA, FLT3, and DHX15 in this subtype of AML. To investigate in-depth the role of ASXL2 in normal and malignant hematopoiesis, we utilized a mouse model of ASXL2 deficiency. Loss of ASXL2 caused progressive hematopoietic defects characterized by myeloid cell expansion, splenomegaly, extramedullary hematopoiesis and poor reconstitution ability in transplantation models. A parallel analysis of young and >1-year old Asxl2-deficient mice revealed age-dependent changes in the hematopoietic compartment leading to perturbations affecting not only myeloid and erythroid differentiation but also maturation of lymphoid cells. Our studies also suggest that expression of truncated ASXL2 protein confers proliferative advantage to mouse myeloid progenitors. Overall, these findings establish a critical role of ASXL2 in maintaining steady state hematopoiesis and provide insights into how its loss/mutation primes leukemic growth of myeloid cells.
Project description:Chromosomal translocation t(8;21) (q22;q22) leading to generation of oncogenic RUNX1-RUNX1T1 (AML1-ETO) fusion is a cytogenetic abnormality observed in about 10% of acute myelogenous leukemia (AML). To uncover somatic mutations that cooperate with t(8;21)-driven leukemia, we performed targeted and whole exome sequencing of newly-diagnosed and relapsed AML samples. We identified high frequency of truncating alterations in ASXL2 along with recurrent mutations of KIT, TET2, MGA, FLT3, and DHX15 in this subtype of AML. To investigate in-depth the role of ASXL2 in normal and malignant hematopoiesis, we utilized a mouse model of ASXL2 deficiency. Loss of ASXL2 caused progressive hematopoietic defects characterized by myeloid cell expansion, splenomegaly, extramedullary hematopoiesis and poor reconstitution ability in transplantation models. A parallel analysis of young and >1-year old Asxl2-deficient mice revealed age-dependent changes in the hematopoietic compartment leading to perturbations affecting not only myeloid and erythroid differentiation but also maturation of lymphoid cells. Our studies also suggest that expression of truncated ASXL2 protein confers proliferative advantage to mouse myeloid progenitors. Overall, these findings establish a critical role of ASXL2 in maintaining steady state hematopoiesis and provide insights into how its loss/mutation primes leukemic growth of myeloid cells.
Project description:The t(8;21) translocation fuses the DNA binding domain of the hematopoietic master regulator RUNX1 to the ETO protein. The resultant RUNX1/ETO fusion protein is a leukemia-initiating transcription factor that interferes with RUNX1 function. The result of this interference is a block in differentiation and, finally, the development of acute myeloid leukemia (AML). To obtain insights into RUNX1/ETO-dependant alterations of the epigenetic landscape we measured genome-wide RUNX1- and RUNX1/ETO bound regions in t(8;21) cells and assessed to what extent the effects of RUNX1/ETO on the epigenome depend on its continued expression in established leukemic cells. To this end we determined dynamic alterations of histone acetylation, RNA Polymerase II binding and RUNX1 occupancy in the presence or absence of RUNX1/ETO using a knockdown approach. Combined global assessments of chromatin accessibility and kinetic gene expression data show that RUNX1/ETO controls the expression of important regulators of hematopoietic differentiation and self-renewal. We show that selective removal of RUNX1/ETO leads to a widespread reversal of epigenetic reprogramming and a genome-wide re-distribution of RUNX1 binding, resulting in the inhibition of leukemic proliferation and self-renewal and the induction of differentiation. This demonstrates that RUNX1/ETO represents a pivotal therapeutic target in AML. This SuperSeries is composed of the following subset Series: GSE29222: Depletion of RUNX1/ETO in t(8;21) AML cells leads to genome-wide changes in chromatin structure and transcription factor binding [ChIP-Seq and DNAse-Hypersensitivity data] GSE29223: Depletion of RUNX1/ETO in t(8;21) AML cells leads to genome-wide changes in chromatin structure and transcription factor binding [expression array data] GSE34540: Depletion of RUNX1/ETO in t(8;21) AML cells leads to genome-wide changes in chromatin structure and transcription factor binding (ChIP-seq) GSE34594: Depletion of RUNX1/ETO in t(8;21) AML cells leads to genome-wide changes in chromatin structure and transcription factor binding (Illumina expression) Refer to individual Series
Project description:ZBTB7A is frequently mutated in acute myeloid leukemia (AML) with t(8;21) translocation. However, the oncogenic collaboration between mutated ZBTB7A and the RUNX1-RUNX1T1 fusion gene in AML t(8;21) remains unclear. Here, we investigate the role of ZBTB7A and its mutations in the context of normal and malignant hematopoiesis.
Project description:The t(8;21) translocation fuses the DNA binding domain of the hematopoietic master regulator RUNX1 to the ETO protein. The resultant RUNX1/ETO fusion protein is a leukemia-initiating transcription factor that interferes with RUNX1 function. The result of this interference is a block in differentiation and, finally, the development of acute myeloid leukemia (AML). To obtain insights into RUNX1/ETO-dependant alterations of the epigenetic landscape we measured genome-wide RUNX1- and RUNX1/ETO bound regions in t(8;21) cells and assessed to what extent the effects of RUNX1/ETO on the epigenome depend on its continued expression in established leukemic cells. To this end we determined dynamic alterations of histone acetylation, RNA Polymerase II binding and RUNX1 occupancy in the presence or absence of RUNX1/ETO using a knockdown approach. Combined global assessments of chromatin accessibility and kinetic gene expression data show that RUNX1/ETO controls the expression of important regulators of hematopoietic differentiation and self-renewal. We show that selective removal of RUNX1/ETO leads to a widespread reversal of epigenetic reprogramming and a genome-wide re-distribution of RUNX1 binding, resulting in the inhibition of leukemic proliferation and self-renewal and the induction of differentiation. This demonstrates that RUNX1/ETO represents a pivotal therapeutic target in AML. 14 samples include: RUNX1 Kasumi-1, RUNX1/ETO control, RUNX1/ETO siMM, RUNX1/ETO siRE, RUNX1_non-t(8;21), H3K9Ac_siMM, H3K9Ac_siRE, POLII_siMM and POLII_siRE ChIP-Seq samples, and Kasumi-1, non-t(8;21), t(8;21) paitent#1, t(8;21) paitent#2 and CD34 normal DNasel HS samples.
Project description:The t(8;21) translocation fuses the DNA binding domain of the hematopoietic master regulator RUNX1 to the ETO protein. The resultant RUNX1/ETO fusion protein is a leukemia-initiating transcription factor that interferes with RUNX1 function. The result of this interference is a block in differentiation and, finally, the development of acute myeloid leukemia (AML). To obtain insights into RUNX1/ETO-dependant alterations of the epigenetic landscape we measured genome-wide RUNX1- and RUNX1/ETO bound regions in t(8;21) cells and assessed to what extent the effects of RUNX1/ETO on the epigenome depend on its continued expression in established leukemic cells. To this end we determined dynamic alterations of histone acetylation, RNA Polymerase II binding and RUNX1 occupancy in the presence or absence of RUNX1/ETO using a knockdown approach. Combined global assessments of chromatin accessibility and kinetic gene expression data show that RUNX1/ETO controls the expression of important regulators of hematopoietic differentiation and self-renewal. We show that selective removal of RUNX1/ETO leads to a widespread reversal of epigenetic reprogramming and a genome-wide re-distribution of RUNX1 binding, resulting in the inhibition of leukemic proliferation and self-renewal and the induction of differentiation. This demonstrates that RUNX1/ETO represents a pivotal therapeutic target in AML. RUNX1 siMM and RUNX1 siRE ChIP-Seq samples and a paired-end ChIP-Seq samples from patients with t(8;21) AML are used in this study; there are two paired-end ChIP-Seq runs and control per patient
Project description:The tumor suppressor and deubiquitinase (DUB) BAP1 regulates chromatin-associated processes and is frequently mutated in various malignancies. BAP1 and its drosophila orthologue Calypso assemble DUB complexes with ASXL-1, -2, -3 paralogues and ASX respectively, and these cofactors are required for stimulating their DUB activity. However how the DUB activity of BAP1 is regulated remains largely unknown. Here we show that BAP1 promotes monoubiquitination of ASXLs on the ASXM/DEUBAD domain. ASXL2 monoubiquitination promotes its stability or proteasomal degradation, stimulates BAP1 DUB activity and is required for mammalian cell proliferation. Monoubiquitination of ASXL2 is directly catalyzed by UBE2E family of ubiquitin conjugating enzymes and is regulated by deubiquitination. Monoubiquitination of ASX is regulated by Calypso and is required for drosophila development. We further revealed a switch mechanism that tightly regulate BAP1 function, as a monoubiquitination of BAP1 UCH domain is mutually exclusive with ASXL2 monoubiquitination, thus ensuring highly coordinated DUB-mediated signaling.