Essential role for Argonaute2 protein in mouse oogenesis

Argonaute2 proteins (Ago2) are key component of RNA-induced gene silencing complexes (RISCs), which is crucial for microRNAs to repress target genes. The function of Ago2 for oogenesis is unknown due to early embryonic lethal of Ago2 knockout mice. Here we show the effect of loss of Ago2 in mouse oogenesis by specific deletion of it in growing oocyte. Although the Ago2-deficient oocytes can develop to mature oocytes, they have abnormal spindle and the chromosomes that can’t cluster together properly, which are very similar to the phenotype of Dicer-deficient oocytes. We checked miRNA expression profile and found that in Ago2-deficient oocyte, the expression of most miRNAs reduced more than 80%. To understand the downstream genes regulated by Ago2, we used microarray on Ago2-deficient oocyte and found that 512 genes were upregulated and 1073 genes were downregulated (FC>2, P<0.05). Our data proved that Ago2 have a key function for mouse oogenesis through globally regulating miRNA stability and function. we run single cell cDNA microarray comparing Ago2-KO oocytes with wild-type GV oocyte controls