The Role of U2AF1 Mutations in Myelodysplastic Syndrome: A Noncanonical Role for Splicing Factors in Bone Marrow Failure
Abstract
Gene expression refers to the sum of processes that enable cells to control their complement of RNA and protein. Massive molecular machines such as RNA polymerase, the spliceosome, and the ribosome carry out the synthesis, processing, and translation of RNA. A central challenge in cell biology is to understand how these processes are coupled and regulated in time and space in single living cells and how this regulation is altered in disease. The differentiation of hematopoietic stem cells into committed lineages in the blood is the result of concerted regulation between transcription, splicing, and translation. Moreover, mutations in the gene expression machinery drive the development of clonal stem cell disorders, which result in bone marrow failure and often leukemia. Specifically, the myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are a heterogeneous group of malignant clonal hematopoietic stem cell disorders with poor prognosis and few treatment options. MDS is characterized by ineffective hematopoiesis, marrow dysplasia, peripheral blood cytopenia, and a high propensity for transformation into AML, which is an acute proliferative disease. Over 60% of MDS patients carry a mutation in the spliceosome which is the macromolecular complex primarily responsible for processing RNA made from DNA into messenger RNA that is translated into protein. However, we have proposed a secondary non-canonical role for the splicing machinery in disease progression. We found that in the presence of mutations in the splicing gene U2AF1 this role is altered, resulting in an inflammatory response that correlates with disease progression. Similarly, mass spectrometry indicates substantial changes in the cellular translation machinery, including ribosome subunits and translation initiation factors. The physiological consequences of this misregulation include non-oncogene addiction to the translation machinery and global upregulation of translation visible even at the single-cell level. These observations suggest that translation of mRNA into protein may have a previously unanticipated role in MDS. The goal of this study is to apply a new set of tools to interrogate the gene regulation processes which are downstream of RNA synthesis. We will use techniques such as mass spectrometry, ribosome footprinting, and pulse-chase metabolic labeling of nascent peptides to decipher general mechanisms of misregulation in MDS. We are particularly interested in changes to inflammation and secretion, which are intimately connected to translation regulation and which occur in the presence of the U2AF1 mutation. We will utilize state-of-the-art techniques to analyze the cytokine family of genes, which are important mediators of inflammation in the bone marrow. Importantly, cytokines also represent a potent and potentially druggable target in bone marrow failure disorders. In fact, current efforts not part of this proposal, but in part based on our preliminary data, are exploring immunotherapy connected to the cytokine Interleukin-8. Overall, gene regulation in this tissue is exceptionally dependent on post-transcriptional mechanisms, opening new avenues of research for understanding hematopoiesis. Analysis of primary human samples and close coupling with the newly established National Institutes of Health Myeloid Malignancies clinical program drives vibrant bench-to-bedside-to-bench research where basic concepts in gene regulation can be immediately applied to human health.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 28, 2022
- Source ID
- W81XWH2210620
Entities
People
- Daniel R Larson
Organizations
- National Cancer Institute
- United States Army