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Genetic variation underlies epigenomic variation and the consequences of DNMT3A mutation in hematopoietic stem cells
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Invited Speaker Abstracts/ Experimental Hematology 53 (2017) S24-S40
1021 - GENETIC VARIATION UNDERLIES EPIGENOMIC VARIATION AND THE CONSEQUENCES OF DNMT3A MUTATION IN HEMATOPOIETIC STEM CELLS Jennifer Trowbridge1, Rebecca Bell1, Catrina Spruce1, Anna Tyler1, Robyn Ball1, Vivek Philip1, Dan Gatti1, Narayanan Raghupathy1, Romy Kurasawe2, Kira Young1, Mary Ann Handel1, Michael Stitzel2, Gary Churchill1, Kenneth Paigen1, Petko Petkov1, and Gregory Carter1 1 The Jackson Laboratory, Bar Harbor, United States; 2The Jackson Laboratory for Genomic Medicine, Farmington, United States Accumulation of somatic mutations in genes including the DNA methyltransferase DNMT3A predisposes many, but not all, individuals to development of clonal hematopoiesis and acute myeloid leukemia (AML). We hypothesize that individual genetic variation underlies distinct epigenomic patterning, and that this variation alters susceptibility to the pathogenic consequences of DNMT3A mutations in hematopoietic stem cells (HSCs). Through a collaborative effort to assess epigenome variation in a genetically diverse model system, we performed an in-depth chromatin analysis of liver cells isolated from 8 classical and wild-derived inbred mouse strains that recapitulate the genetic diversity of the human population. Comparing histone modification ChIP-seq, RNA-seq, and reduced representation bisulfite sequencing analysis to the sequenced genome of each of these strains demonstrates that underlying genetic variation leads to alterations in epigenetic patterning and establishment of distinct regulatory regions of the epigenome. To determine whether distinct epigenomic backgrounds influence response to mutations in DNMT3A, we generated an inducible knock-in mouse model of the most common human AML-associated DNMT3AR882H allele (mouse Dnmt3aR878H). This mouse was generated on a C57BL/6 background and crossed to the 8 inbred mouse strains described above. Following Mx-Cre induction of Dnmt3aR878H, we observe variability in HSC expansion and myeloid cell accumulation as a consequence of genetic background. Our work suggests that individual genetic differences can alter susceptibility to clonal hematopoiesis and AML development following mutation in DNMT3A.
1022 - MITOCHONDRIA IN THE REGULATION OF HEMATOPOIETIC STEM CELLS Saghi Ghaffari1,2,3 1 Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, United States; 2 Black Family Stem Cell Institute, New York, United States; 3Tisch Cancer Institute, New York, United States Hematopoietic stem cells (HSCs) like most, if not all, adult stem cells are primarily quiescent but have the potential to become highly active when needed. HSCs accumulate low levels of reactive oxygen species (ROS) despite containing a significant number of mitochondria suggesting that mitochondria are relatively inactive in quiescent HSC. However, HSC cycling – and exit of quiescence state – involves a switch to mitochondrial oxidative phosphorylation from glycolysis. While HSC differentiation requires mitochondrial metabolism, the role of mitochondria in the maintenance of HSC quiescence is less clear. We find that mitochondrial activity is highly heterogeneous within the immuno-phenotypically defined long-term hematopoietic stem cell compartment. Our evidence suggests that mitochondrial activity segregates quiescent from primed activated HSC. In addition, combined alterations in mitochondrial metabolic functions and morphological attributes contribute to loss of HSC fitness. Overall our studies indicate that mitochondrial shape and metabolic functions are required not only for HSC differentiation but also for HSC health. These studies have implications for HSC aging and malignancies.
Invited Speaker Abstracts/ Experimental Hematology 53 (2017) S24-S40
1021 - GENETIC VARIATION UNDERLIES EPIGENOMIC VARIATION AND THE CONSEQUENCES OF DNMT3A MUTATION IN HEMATOPOIETIC STEM CELLS Jennifer Trowbridge1, Rebecca Bell1, Catrina Spruce1, Anna Tyler1, Robyn Ball1, Vivek Philip1, Dan Gatti1, Narayanan Raghupathy1, Romy Kurasawe2, Kira Young1, Mary Ann Handel1, Michael Stitzel2, Gary Churchill1, Kenneth Paigen1, Petko Petkov1, and Gregory Carter1 1 The Jackson Laboratory, Bar Harbor, United States; 2The Jackson Laboratory for Genomic Medicine, Farmington, United States Accumulation of somatic mutations in genes including the DNA methyltransferase DNMT3A predisposes many, but not all, individuals to development of clonal hematopoiesis and acute myeloid leukemia (AML). We hypothesize that individual genetic variation underlies distinct epigenomic patterning, and that this variation alters susceptibility to the pathogenic consequences of DNMT3A mutations in hematopoietic stem cells (HSCs). Through a collaborative effort to assess epigenome variation in a genetically diverse model system, we performed an in-depth chromatin analysis of liver cells isolated from 8 classical and wild-derived inbred mouse strains that recapitulate the genetic diversity of the human population. Comparing histone modification ChIP-seq, RNA-seq, and reduced representation bisulfite sequencing analysis to the sequenced genome of each of these strains demonstrates that underlying genetic variation leads to alterations in epigenetic patterning and establishment of distinct regulatory regions of the epigenome. To determine whether distinct epigenomic backgrounds influence response to mutations in DNMT3A, we generated an inducible knock-in mouse model of the most common human AML-associated DNMT3AR882H allele (mouse Dnmt3aR878H). This mouse was generated on a C57BL/6 background and crossed to the 8 inbred mouse strains described above. Following Mx-Cre induction of Dnmt3aR878H, we observe variability in HSC expansion and myeloid cell accumulation as a consequence of genetic background. Our work suggests that individual genetic differences can alter susceptibility to clonal hematopoiesis and AML development following mutation in DNMT3A.
1022 - MITOCHONDRIA IN THE REGULATION OF HEMATOPOIETIC STEM CELLS Saghi Ghaffari1,2,3 1 Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, United States; 2 Black Family Stem Cell Institute, New York, United States; 3Tisch Cancer Institute, New York, United States Hematopoietic stem cells (HSCs) like most, if not all, adult stem cells are primarily quiescent but have the potential to become highly active when needed. HSCs accumulate low levels of reactive oxygen species (ROS) despite containing a significant number of mitochondria suggesting that mitochondria are relatively inactive in quiescent HSC. However, HSC cycling – and exit of quiescence state – involves a switch to mitochondrial oxidative phosphorylation from glycolysis. While HSC differentiation requires mitochondrial metabolism, the role of mitochondria in the maintenance of HSC quiescence is less clear. We find that mitochondrial activity is highly heterogeneous within the immuno-phenotypically defined long-term hematopoietic stem cell compartment. Our evidence suggests that mitochondrial activity segregates quiescent from primed activated HSC. In addition, combined alterations in mitochondrial metabolic functions and morphological attributes contribute to loss of HSC fitness. Overall our studies indicate that mitochondrial shape and metabolic functions are required not only for HSC differentiation but also for HSC health. These studies have implications for HSC aging and malignancies.