Poster abstracts
Poster number 27 submitted by Matias Montes
The nuclear microRNA miR-29b binds to MDM2 pre-mRNA to influence its alternative splicing
Matias Montes (Nationwide Childrens Hospital), Huating Wang ( The Chinese University of Hong Kong), Denis C. Guttridge ( Medical University of South Carolina), Dawn S. Chandler (Nationwide Childrens Hospital)
Abstract:
Alternative splicing plays a critical role in development and in cancer. Genotoxic stress
can modulate the alternative splicing of several genes including the oncogene MDM2, but
the mechanism of its regulation remains poorly understood. Here we report that miR-29b
is expressed at high levels in normal cells but decreased under conditions of genotoxic
stress and in rhabdomyosarcoma cells, both of which are characterized by the expression
of the splice isoform MDM2-ALT1. We sought to identify the elusive nuclear function of
miR-29b. In this work, we show that this microRNA can directly bind to the MDM2 pre-
mRNA and drive splicing choices. Through the use of minigene constructs and CRISPR-
Cas9 genome engineering, we show that miR-29b binds specifically to the MDM2 pre-
mRNA in normal cells and has decreased binding after genotoxic stress. Overexpression
of the pre-miR-29b can alleviate the induction of the MDM2-ALT1 isoform in response to
genotoxic stress. We provide evidence that miR-29b represents the first reported miRNA
to function as a splicing factor, bringing together two critical cellular processes in human
disease: miRNAs and alternative splicing.
Keywords: miR-29b, MDM2, Alternative Splicing