PROJECT SUMMARY/ABSTRACT: This proposal for a Mentored Clinical Scientist Research Career Development Award (K08) outlines a comprehensive training program for the career development of the applicant Dr. Prajwal Boddu as an independent physician scientist. The focus of scientific investigation is myelodysplastic syndrome (MDS), the most common cause of bone marrow failure in adults. Mutations in well-defined groups of genes (splicing factors, epigenetic regulators) underlie most MDS. SF3B1 mutations are most common among splicing factors, accounting for about 20% of MDS cases. Conventional models assign disruption of alternative splicing to be the primary cause of splicing factor mutant MDS, but many limitations to these studies have prompted alternate hypotheses. In this application, we consider an additional context in which splicing factors function – specifically, their role in the regulation of RNA transcription. Given the close interplay between RNA transcription and splicing, we explored how SF3B1 mutations affect transcription kinetics. Our studies show that SF3B1 mutations disrupt RNA Polymerase II (Pol II) transcription, leading to a profound reshaping of chromatin architecture, and yielding targetable epigenetic modifications. Consequently, we redefine SF3B1-mutant MDS functionally as an epigenetic disorder. Based on these preliminary results, this proposal will delve into the molecular mechanisms that link SF3B1 mutations to Pol II elongation defects and altered chromatin accessibility. The first aim will explore a novel hypothesis that mutant SF3B1 impairs early spliceosome assembly, affecting Pol II density at gene promoters, ultimately leading to chromatin closure and altered gene expression. The second aim will investigate the impact of these transcription defects on higher order chromatin (3D genome). Recent studies have pointed to the link between 3D genome reorganization and clonal evolution and aberrant gene expression patterns in many clonal processes. The third aim seeks to leverage data from an unbiased screen that shows reversal of transcription defects through inhibition of chromatin modulators such as those in the Sin3/HDAC complex. Using patient derived xenograft (PDX) models, we will explore therapeutic targeting of these chromatin modulators. The application seeks to expand the principal investigator’s training in RNA splicing, transcription biology, and epigenetics under the mentorship of Dr. Manoj Pillai, a physician scientist with expertise in RNA mechanisms and hematopoiesis, alongside co-mentor Dr. Karla Neugebauer, a pioneer in the field of co-transcriptional splicing. Additional expertise will be provided by an advisory committee comprising of Drs Andrew Xiao (epigenetics) and Amit Verma (patient-derived xenograft modeling and pre-clinical studies of MDS). Yale University provides exceptional opportunities for both training and career development for aspiring physician scientists such as Dr. Boddu. A carefully ...