5S RNA Regulation and Ribosome Biogenesis

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The research is directed toward studying the regulation of 5S RNA, which is one component of ribosome biogenesis. In higher eukaryotes, 5S RNA is small 120 nts RNA which, although an essential component of ribosomes, is still only partially understood in its ribosome location and function. In somatic cells 5S RNA is synthesized in the nucleus, and targeted to the nucleolus where it is incorporated into nascent larger ribosomal subunits. In oocytes, the synthesis of a large amount of 5S RNA precedes by several weeks, the activation of rRNA and r protein synthesis and the beginning of ribosome biogenesis. Therefore, this naturally occurring a synchrony in the on set of synthesis of ribosome components affords us a unique opportunity to study the various step sand the regulation involved in the targeting of 5S RNA to the nucleolus and the requirements for 5S RNA incorporation how 5S RNA is added to the nascent large ribosomal subunit during oogenesis in Xenopus laevis. A further aim is to establish the mechanism(s) for ferrying the 5S RNA out to the cytoplasm, keeping it stored there, and then transporting it back into the nucleus, specifically into the nucleolus. In a larger context, the oocyte system will facilitate our understanding of how nuclear proteins interact with specific RNA molecules, and what is required for transport of RNPs in and out of the nucleus. The oocyte studies will likely amplify our understanding of how somatic cell 5S RNAis targeted to and incorporated into nascent ribosomes forming with in the nucleolus, a process which probably occurs entirely with in the somatic cell nucleus.