Is Genomic Imprinting Related to the Presence of miRNAs within the Sfm-nbt2 Locus?

JULS Volume 10, Issue 1

Cathy Su1, Susannah Varmuza2

1 Department of Biological Physics, University of Toronto, Toronto, Canada
2 Department of Cell and Systems Biology, University of Toronto, Toronto, Canada

Corresponding Author: Cathy Su (


Sfmbt2 is a gene maternally imprinted in mouse trophoblast tissues. Whereas the majority of imprinted genes are clustered beside each other, exist near an imprinting control region, and are regulated mainly by DNA methylation and long non-coding RNAs, none of these statements appear to hold true for Sfmbt2. Its mechanism of imprinting is currently unknown. However, one unique attribute of this gene is the block of miRNAs present in its tenth intron, whose function has yet to be characterized. To determine if this miRNA block is involved in the imprinting of Sfmbt2, a CRISPR-Cas9 system with two gRNAs was used to delete this region within a mouse trophoblast cell culture. This deletion had no effect on imprinted expression as determined by cDNA sequencing. However, methylation analysis of bisulfite sequencing data for this cell culture revealed that the cultured trophoblast stem cells used in this study had a different epigenetic profile than cells in vivo because of methylation around the promoter region of Sfmbt2. As such, additional studies are needed in order to determine if this miRNA block is driving genomic imprinting at Sfmbt2 in vivo.