Poster abstracts
Poster number 29 submitted by Noah Daniels
Investigating the Role of DDX41 in pre-messenger RNA Splicing and Leukemogenesis
Noah J. Daniels (Cardiovascular and Metabolic Sciences, Cleveland Clinic), James M. Hiznay, Courtney E. Hershber, William DiPasquale, Devlin C. Moyer (Cardiovascular and Metabolic Sciences, Cleveland Clinic), Sukanya Srinivasan, Eckhard Jankowsky (RNA Science and Therapeutics, Case Western Reserve University), Jaroslaw P. Maciejewski (Translational Hematology and Oncology Research, Cleveland Clinic), Richard A. Padgett1 (Cardiovascular and Metabolic Sciences, Cleveland Clinic)
Abstract:
DEAD-box RNA helicases are a highly conserved family of proteins involved in nearly all aspects of RNA metabolism, including several members with crucial roles in pre-messenger RNA splicing. Whole exome sequencing has identified DDX41, a member of this family, as recurrently mutated in patients diagnosed with the bone marrow neoplasm, myelodysplastic syndrome (MDS). Germline frameshift DDX41 mutations potentially causing DDX41 hemizygosity throughout life have been identified in numerous families with histories of MDS and leukemia. Nearly half of these individuals will acquire a recurrent, somatic, missense mutation, resulting in the conversion of arginine 525 to histidine (R525H) in the highly conserved helicase domain of the second DDX41 allele. Biochemical assays in vitro with recombinant DDX41 R525H displayed slightly tighter binding of double stranded RNA and a 4-fold decrease in RNA duplex unwinding compared with DDX41 WT protein; this suggests a hypomorphic function. Proteomic analyses have classified DDX41 as a member of the catalytic core of the spliceosome but its role in splicing is still undefined. Analysis of RNA cross-linking-immunoprecipitation-high-throughput-sequencing data demonstrated that DDX41 binds preferentially to exons and splice sites of pre-mRNAs. Furthermore, DDX41 binds to both major and minor class spliceosomal snRNAs. RNA-seq analyses of DDX41 WT and DDX41 R525H over-expression or DDX41 knockdown human cells have revealed subtle-yet wide-spread-effects on pre-mRNA splicing. These data support our hypothesis that DDX41 is a component of the spliceosome and plays an important role in pre-mRNA splicing. Alterations of DDX41 may result in the aberrant splicing of key leukemogenic drivers.
Keywords: DDX41, pre-mRNA Splicing, Myelodysplastic Syndrome