Talk abstracts
Talk on Saturday 11:30-11:45am submitted by Courtney Hershberger
LUC7L2 is a splicing regulatory protein that is frequently mutated in bone marrow neoplasms
Hershberger C.E. (Cleveland Clinic Foundation, Cleveland, OH), Gu, X., Dietrich, R.C., Hiznay J. (Cleveland Clinic Foundation, Cleveland, OH), Hosono N. (University of Fukui, Fukui, Japan), Makishima, H. (Kyoto University, Kyoto, Japan), Saunthararajah, Y., Maciejewski J. (Cleveland Clinic Foundation, Cleveland, OH), Padgett R.A. (Cleveland Clinic Foundation, Cleveland, OH)
Abstract:
Myelodysplastic syndrome (MDS) is a disease distinguished by the large percentage of patients that harbor a mutation in one of several splicing factors. Exome sequencing of patient bone marrow samples recently identified frameshift mutations and deletions encompassing the putative splicing factor gene LUC7L2 in 14% of MDS patients. Low expression of LUC7L2 is correlated with worse prognosis suggesting that LUC7L2-deficiency contributes to the pathology of MDS. While it is known that the essential orthologous yeast protein Luc7p is involved in 5’ splice site recognition, little is understood about the function of mammalian LUC7L2. To understand the pathology of LUC7L2-deficiency, we characterized its role as a splicing factor using co-immunoprecipitation mass spectrometry, CLIP-Seq, RNA-Seq and intron splicing efficiency assays.
In this work, we demonstrate that LUC7L2 interacts with both core and regulatory spliceosomal proteins. LUC7L2 binds selectively to over 300 pre-mRNA transcripts and early acting snRNAs. LUC7L2 binding on pre-mRNA is enriched 20-fold in splice site proximal regions. Knocking down LUC7L2 in HEK293 and K562 cells lines results in changes to constitutive and alternative splicing with removal of alternatively-spliced introns being the group most frequently affected. Validation of target-transcripts confirms increases in intron splicing efficiency, suggesting that LUC7L2 plays the role of a splicing repressor. Parallel analysis of published RNA-Seq datasets for SF3B1, U2AF1 and SRSF2 mutations in K562 cells has revealed commonly mis-spliced targets PRC1, MRPL33, PTBP1 and U2AF1. These transcripts are candidates for further study of the influence of alternatively spliced transcripts on the progression of disease. To our knowledge this is the first description of LUC7L2 as a splicing regulatory factor. This work provides insights into the function of LUC7L2, providing the framework for our intensive examination of its role in MDS in the future.
Keywords: Alternative Splicing, MDS, LUC7L2