Contributions
Abstract: EP391
Type: E-Poster Presentation
Session title: Acute myeloid leukemia - Biology & Translational Research
Background
Human aged hematopoietic stem and progenitor cells (HSPCs) are prone to clonal expansion due to the acquisition of recurrent somatic mutations. This phenomenon is known as age-related clonal hematopoiesis (ARCH). While somatic pre-leukemic mutations (pLMs) which define ARCH are mostly nonsynonymous single nucleotide variants (SNVs), insertions and deletions (indels) are less common and the mutational mechanisms underlying indels are less understood.
Aims
In the current study we aim to characterize mutational processes leading to recurrent deletions in clonal hematopoiesis.
Methods
We used CRISPR/Cas9 system to introduce targeted DSBs into the hotspot region of ASXL1 and SRSF2 genes to recapitulate recurrent deletions in these genes. We further studied the mutational mechanisms leading to these deletions by in vitro knock out models and PARP1 inhibitor treatments.
Results
In the current study we inspected the genomic regions around recurrent deletions in myeloid malignancies, and identified microhomology (MH)-based signatures in CALR, ASXL1 and SRSF2 loci. We demonstrate that these deletions are the result of double stand break (DSB) repair by a PARP1 mediated Microhomology-mediated end joining (MMEJ) pathway. Importantly, we provide evidence that recurrent MH-based deletions originate in pre-leukemic HSCs, suggesting an MMEJ predominance in clonal hematopoiesis. While polymerase theta (POLQ) is considered a key component in MMEJ repair, we provide evidence that pre-leukemic MMEJ (preL-MMEJ) deletions can be generated in POLQ knock out cells. In contrast, inhibition of the replicative polymerases (which are co-expressed with PARP1 in human HSCs) resulted in a significant reduction in preL-MMEJ.
Conclusion
Our data indicate an association between polymerase theta independent MMEJ and clonal hematopoiesis and elucidate mutational mechanisms involved in the very first steps of leukemia evolution.
Keyword(s): AML, DNA repair, Mutation, Stem and progenitor cell
Abstract: EP391
Type: E-Poster Presentation
Session title: Acute myeloid leukemia - Biology & Translational Research
Background
Human aged hematopoietic stem and progenitor cells (HSPCs) are prone to clonal expansion due to the acquisition of recurrent somatic mutations. This phenomenon is known as age-related clonal hematopoiesis (ARCH). While somatic pre-leukemic mutations (pLMs) which define ARCH are mostly nonsynonymous single nucleotide variants (SNVs), insertions and deletions (indels) are less common and the mutational mechanisms underlying indels are less understood.
Aims
In the current study we aim to characterize mutational processes leading to recurrent deletions in clonal hematopoiesis.
Methods
We used CRISPR/Cas9 system to introduce targeted DSBs into the hotspot region of ASXL1 and SRSF2 genes to recapitulate recurrent deletions in these genes. We further studied the mutational mechanisms leading to these deletions by in vitro knock out models and PARP1 inhibitor treatments.
Results
In the current study we inspected the genomic regions around recurrent deletions in myeloid malignancies, and identified microhomology (MH)-based signatures in CALR, ASXL1 and SRSF2 loci. We demonstrate that these deletions are the result of double stand break (DSB) repair by a PARP1 mediated Microhomology-mediated end joining (MMEJ) pathway. Importantly, we provide evidence that recurrent MH-based deletions originate in pre-leukemic HSCs, suggesting an MMEJ predominance in clonal hematopoiesis. While polymerase theta (POLQ) is considered a key component in MMEJ repair, we provide evidence that pre-leukemic MMEJ (preL-MMEJ) deletions can be generated in POLQ knock out cells. In contrast, inhibition of the replicative polymerases (which are co-expressed with PARP1 in human HSCs) resulted in a significant reduction in preL-MMEJ.
Conclusion
Our data indicate an association between polymerase theta independent MMEJ and clonal hematopoiesis and elucidate mutational mechanisms involved in the very first steps of leukemia evolution.
Keyword(s): AML, DNA repair, Mutation, Stem and progenitor cell