Abstract:
Our earlier study revealed robust production of short interfering RNAs(siRNAs) in the oocyte but not in somatic tissues in the mouse. We now report that growing mouse oocytes express a unique, N-terminally truncated isoform of Dicer, the small RNA-producing enzyme. Our data show that this Dicer isoform is responsible for increased production of endogenous siRNAs in the oocyte. The oocyte-specific Dicer isoform is the first evidence for molecular divergence of mammalian miRNA and RNAi mechanisms. Notably, production of oocyte-specific Dicer is controlled by a rodent-specific retrotransposon. This fact has interesting implications regarding evolution and conservation of RNA silencing pathways in animals.
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