During metazoan development, polarization of the body axes is of critical importance, as asymmetric cell division initiates cell specialization pathways. A family of conserved RNA-binding proteins characterized by CCCH-type tandem zinc finger (TZF) domains is required for axis polarization and cell type specification in the early embryo of C. elegans. A cascade of events essential to the oocyte- to-embryo transition is initiated by two members of this family, OMA-1/2. The process initiates with OMA-1/2 turnover and culminates with asymmetric segregation of cellular components to opposing poles of the embryo. Mutation of OMA-1/2 blocks oocyte maturation and prevents fertilization. We have observed that OMA-1 binds RNA with relatively low specificity in vitro, but regulates specific mRNAs in vivo. We have also determined that OMA-1 RNA binding is highly cooperative, a feature never before observed in a protein from the CCCH-type TZF family. Our goal is to investigate OMA- 1/2 activity from structure to phenotype. We will determine the molecular mechanism or RNA-binding cooperativity using NMR spectroscopy, computer simulations, and quantitative biochemistry. We will also define how RNA-binding cooperativity defines OMA-1 biological activity in worms. We will determine which mRNAs are regulated by OMA-1/2 in oocytes and of these mRNAs which are the most critical to reproduction. This research will lead to a new understanding of how the molecular properties of OMA-1 determine its function in reproductive biology in living animals.
Post-transcriptional regulation of maternal mRNAs is responsible for many of the developmental events that occur in the early stages of embryogenesis. By understanding the mechanisms that regulate mRNAs during the oocyte-to-embryo transition our research will identify how this control is tied to the development of living cells and will ultimately provide insights into the molecular basis of congenital developmental diseases.
