RNA Binding Protein Networks and Translational Regulation in Oocytes

After completing the growth phase in preovulatory follicles, oocytes remain arrested in meiotic prophase and are incompetent for fertilization. Upon gonadotropin stimulation, a subpopulation of oocytes reenters meiosis and complete nuclear maturation. At the same time, they undergo major, but poorly delineated, molecular and organelle remodeling, a process that is termed “cytoplasmic maturation” and is necessary to generate an egg competent for embryo development. Establishment of this developmental competence takes place in the absence of transcription and relies entirely on the translation of mRNAs transcribed earlier during growth. A large class of RNA-binding proteins (RBPs), often unique to the oocyte, orchestrates this program of maternal mRNA unmasking, translation, and degradation. Thus, translational regulations are indispensable for progression through meiosis and nuclear maturation as well as for assembling the machinery required for transition to a totipotent cell. Elucidating the molecular details of translational control in oocytes is crucial to understanding female infertility, defects in embryonic development, and other human pathologies linked to defective gene expression, such as cancer. Here, we will review the components and major functions associated with translational regulation of maternal mRNAs in the oocytes and summarize the principles and functional significance of these regulations.