Poster abstracts
Poster number 44 submitted by Matias Montes
Elucidating the mechanisms for MDM2 alternative splicing regulation: The role of SRSF2 and miR29-b
Matias Montes (Molecular, Cellular and Developmental Biology Graduate Program, The Ohio State University), Daniel Comiskey (Molecular, Cellular and Developmental Biology Graduate Program, The Ohio State University), Dawn Chandler (Center for Childhood Cancer and Blood Diseases, Nationwide Childrens Hospital)
Abstract:
MDM2, a well-known negative regulator of the tumor suppressor protein P53, goes through alternative splicing and one of its spliced isoforms, MDM2-ALT1 comprised of exons 3 and 12, is highly expressed in several cancers such as lung carcinoma, liposarcoma or rhabdomyosarcoma, correlating its expression with a poor disease prognosis. MDM2-ALT1 expression is also upregulated under conditions of cellular genotoxic stress. Nevertheless, the way that MDM2 splicing is controlled is not entirely understood.
The micro RNA 29-b is part of the miR-29 family, and has been reported as one of the miRNAs that localize inside of the nucleus, but its function there still it is not well understood. Additionally, this miRNA has been shown to act as a tumor suppressor in certain cancer and also being downregulated in rhabdomyosarcoma. Recent studies have shown that some of the splicing factors can be regulated through miRNA-mediated gene silencing, nevertheless, to this day there is no decisive evidence showing direct regulation of alternative splicing by miRNAs.
In this study by using our minigene system and the CRISPR-Cas9 technology, we explore the role of the splicing factor SRSF2 in the alternative splicing of MDM2, hypothesizing that the splicing factor SRSF2 is involved in the splicing of MDM2. On the other hand, we investigate the idea that the miR29-b also plays a role in the alternative splicing of MDM2, by transfecting either a miR-29b or a non-specific miRNA precursor and measuring its effects on the MDM2-ALT1 expression after genotoxic stress. Our results show that SRSF2 acts as a positive regulator of the MDM2 alternative splicing, which is conserved in both mice and humans. Additionally, we show that the miR-29b is implicated in the expression of MDM2-ALT1, which could implicate for the very first time that a miRNA would be acting as a splicing factor, a novel function for these non-coding RNAs.
Keywords: miR-29b, SRSF2, MDM2-Alt1