Understanding how changes in spatial chromatin organization cause defective gene expression in acute myeloid leukemia with STAG2 mutations
Cohesin genes are frequently mutated in acute myeloid leukemia (AML), but the exact mechanisms underlying their relevance in hematopoietic stem cell biology are unknown. STAG2 is the most frequently mutated cohesin member in AML and characterized by a specific set of co-mutations, while its paralogue STAG1 is frequently affected in bladder and breast cancers but hardly ever mutated in myeloid malignancies. With this follow-up proposal, we would like to continue unraveling the importance of STAG2 mutations in spatial chromatin organization and gene expression in AML. Based on our preliminary work, we hypothesize that STAG2 mutations specifically affect interactions between regulatory elements. Here, we propose to focus on the effects of STAG2 loss on promoter-enhancer interactions in STAG2 mutant AMLs using Hi-C (already available; see preliminary work) as well as high resolution Micro-C-enhancer-promoter capture for the same patients. In addition, we aim to study the synergistic effects with distinct co-occurring mutations, including SRSF2 and ASXL1.We will further address the mechanisms responsible for different roles of STAG1 or STAG2 in human myeloid progenitors by identifying immediate STAG1 and STAG2 targets. Here we will utilize degron-technology in a human hematopoietic cell model to follow the effects of rapid STAG protein depletion on epigenetic features and nascent transcription, both, on the level of progenitor cells as well as during myeloid differentiation. The results obtained from this project will reveal fundamental insights into overlapping and distinct functions of STAG1 and STAG2 in hematopoietic cells and the effects of mutated STAG2 on 3D chromatin folding and gene regulation in primary AML cells.
Dr. Claudia Gebhard,Regensburg
Leibniz-Institut für Immuntherapie