Dicer is essential for mouse development

To address the biological function of RNA interference (RNAi) related pathways in mammals, we disrupted the gene Dicer1 in mice. Loss of Dicer1 lead to lethality early in development, with Dicer1 - null embryos depleted of stem cells. Coupled with our inability to generate viable Dicer1 - null embryonic stem (ES) cells, this suggests a role for Dicer, and, by implication, the RNAi machinery, in maintaining the stem cell population during early mouse development.