Poster abstracts
Poster number 51 submitted by Courtney Hershberger
The role of LUC7L2 in splicing and bone marrow failure
Courtney E. Hershberger (Cellular and Molecular Medicine, Cleveland Clinic Foundation), Naoko Hosono (Taussig Cancer Institute, Cleveland Clinic Foundation), Hideki Makishima (Taussig Cancer Institute, Cleveland Clinic Foundation), Jarnail Singh (Cellular and Molecular Medicine, Cleveland Clinic Foundation), Jaroslaw P. Maciejewski (Taussig Cancer Institute, Cleveland Clinic Foundation), Richard A. Padgett (Cellular and Molecular Medicine, Cleveland Clinic Foundation)
Abstract:
Myelodysplastic syndromes (MDS) are a group of disorders characterized by bone marrow failure and frequent progression to acute myeloid leukemia (AML). MDS is the most common hematological malignancy in patients over 65, with only 35% surviving three years after diagnosis. Recent studies have shown that over 65% of MDS patients harbor recurrent point mutations in several proteins involved in spliceosomal splicing. One of these is the poorly characterized splicing-related protein, LUC7L2. 14% of MDS patients are deficient in LUC7L2 expression and this low expression is correlated with more rapid disease progression and decreased survival. The function of LUC7L2 is unknown, but its yeast ortholog LUC7 is involved in recruitment of early splicing factors. We hypothesize that LUC7L2 acts as a mammalian splicing factor and deficiency of LUC7L2 results in aberrant splicing of oncogenes and tumor suppressor genes that contribute to the pathogenesis of MDS. To test this hypothesis, the protein binding-partners of LUC7L2 were examined by immunoprecipitation followed by mass spectrometry. This experiment confirmed that LUC7L2 interacts with snRNP-associated proteins and SR proteins. RNA crosslinking and immunoprecipitation followed by high-throughput sequencing was performed to identify the RNA binding sites of LUC7L2. The analysis showed that LUC7L2 binds the snRNAs, most often the early splicing factors U1, U2, and U12. It also crosslinks to at least 300 pre-mRNA transcripts where the binding sites are located in exons near splice junctions consistent with a role in exon definition. LUC7L2-knockdown cells show reduced splicing of a subset of introns. Finally, RNA-Seq transcriptomes of AML patient samples with and without LUC7L2-deficiency were compared and differential splicing of at least 44 transcripts was detected. Therefore, LUC7L2 demonstrates the characteristics of a splicing factor that binds pre-mRNA, influencing splicing, and the transcripts it binds are candidates for further study in the pathogenesis of MDS.
Keywords: LUC7L2, Pre-mRNA Splicing, Myeloid Neoplasm