Biology Department Faculty

Laura E. Hake

Associate Professor

Current Projects

CPEB

Cytoplasmic polyadenylation element binding protein was the first component of the polyadenylation-induced translation mechanism to be identified and cloned. CPEB is involved in both the translational repression of stored maternal mRNAs and their translational activation. We are exploring how these two apects of CPEB function are regulated during meiosis in response to the signal transduction cascade using phosphopeptide analysis, site directed mutagenesis and overexpression assays, and perturbation of known signal transduction components. We have found that a subset of CPEB within the oocyte is targeted for degradation by the ubiquitin-proteasome pathway during meiosis. We are also learning about CPEB regulation through the identification and characterization of additional CPEB interacting proteins using the yeast two hybrid system and large scale immunoprecipitation.

XGef

XGef is a CPEB interacting protein that we identified using a yeast two hybrid screen. XGef is a Rho-family guanine nucleotide exchange factor. Extensive functional characterization has revealed that XGef interacts directly with CPEB in oocytes and participates in the activation of CPEB function in c-mos mRNA polyadenylation-induced translation. Through the creation of XGef deletion mutants, we have found that the influence of XGef on early CPEB phosphorylation requires that XGef interact with CPEB and that XGef retain exchange activity. The latter observation implies that the classical role of XGef, to activate a Rho-family G-protein, is also required for early signal transduction during meiosis. To date, small G-protein function has not been implicated in these early meiotic events, and we are currently attempting to identify the G-protein that is involved with XGef during early meiosis.