Project description:PGCs undergo two distinct stages of demethylation before reaching a hypomethylated ground state at E13.5. Stage 1 occurs between E7.25- E9.5 in which PGCs experience a global loss of cytosine methylation. However, discreet loci escape this global loss of methylation and between E10.5-E13.5, stage 2 of demethylation takes place. In this stage these loci are targeted by Tet1 and Tet2 leading to the loss of the remaining methylation and resulting in the epigenetic ground state. Our data shows that Dnmt1 is responsible for maintaining the methylation of loci that escape stage 1 demethylation, and that it functions in a UHRF1 independent manner. Our data further demonstrates that when these loci lose methylation prior to stage 2 it results in early activation of the meiotic program, which leads to precocious differentiation of the germ line resulting in a decreased pool of PGCs in the embryo and subsequent infertility in adult mice.
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:Histones were isolated from brown adipose tissue and liver from mice housed at 28, 22, or 8 C. Quantitative top- or middle-down approaches were used to quantitate histone H4 and H3.2 proteoforms. See published article for complimentary RNA-seq and RRBS datasets.