Maternal MicroRNAs are Essential for Mouse Zygotic Development

MicroRNAs (miRNAs) have been shown to have important functions in a variety of cellular processes. Here we report on miRNA expression and their dynamic regulation during mouse oogenesis and early embryos. We show that following specific deletion of Dicer from growing oocytes, the mutant oocytes cease development and were unable to progress through the first cell division. While the mutant mature oocytes seemed morphologically normal, they had disorganized spindle. Using detailed single cell cDNA microarray analysis of normal versus mutant oocytes, we found that a large proportion of maternal genes, including C-mos, are under the control of miRNAs. This study provides strong evidence that maternal miRNAs are essential for the earliest stages of mouse embryonic development. mRNA expression was compared with miRNA expression in dicer knockout and wild-type mouse mature oocyte.