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Research Summary Post-transcriptional regulatory mechanisms have recently emerged as central players regulating the diversification and spationtemporal control of the proteome. The interaction between proteins and individual RNA, which is rapidly initiated in the nucleus following transcription, forms large Ribo-Nucleo Particles (RNPs) that are key in regulating downstream events of the RNA life cycle. These important events include alternative splicing, mRNA transport and localization, as well as translation. Understanding the precise relationship between individual RNA and specific proteins in the formation of RNA-protein complexes is essential to our complete understanding of the gene expression program. Global Characterization of the Alternative pre-mRNA Splicing Network One surprising result from the recent sequencing of the human genome was that the number of predicted genes is significantly lower than had been anticipated. Alternative pre-mRNA splicing is a powerful, important, and prevalent strategy that higher eukaryotes have developed to increase the number of different proteins encoded by their genome. Moreover, alternative splicing plays a major role in gene regulation, is frequently developmentally or tissue-specifically regulated, and can generate distinct protein isoforms with different functions. Even today, the molecular mechanisms governing alternative splicing are poorly understood. The key regulatory proteins, as well as the mechanisms identified thus far, are well conserved between metazoan species. Hence, the use of the fruit fly Drosophila melanogaster, with its small and well-annotated genome, continues to be a powerful system with which to decipher the mechanisms involved in alternative pre-mRNA splicing. My laboratory is interested in understanding the detailed mechanisms involved in establishing a specific alternative splicing program in a given cellular environment. Our efforts concentrate on three major areas: 1) identification of genes and splicing events regulated by specific splicing factors, 2) identification of the protein factors and RNA sequence elements controlling specific alternative splicing events, and 3) characterization of the detailed molecular mechanisms controlling specific alternative splicing events. Drosophila EJC, Genesis and Functions in Gene Regulation The early events into which an RNA associates with specific RNA binding proteins seem to be a crucial determinant in the downstream steps controlling post-transcriptional gene regulation. In order to understand how a given gene expression program is established, we need have a better understanding of how RNPs are assembled and what are the roles of the different components in the diverse aspect of the mRNA metabolism. Recently, it has been found that splicing of introns from pre-mRNAs triggers assembly of a complex on the spliced mRNA called the Exon-Junction Complex (EJC). The EJC have been shown to play a central role on the expression of specific genes including mRNA localization, translation and mRNA stability. Using a combination of molecular biology assay and global analysis, we are currently investigating the assembly and the role of Drosophila EJC in controlling various aspect of mRNA processing and gene regulation. The RNP has a Central Player in Gene Regulation Our current effort in understanding RNP biogenesis will lead to a better understanding of the pathways and components involved in forming individual ribonucleoprotein complexes. This should help us draft a better picture of the contribution of different RNP components in establishing a specific cellular gene expression program. Academic Appointment: Assistant Professor, Department of Pathology & Laboratory Medicine, The University of Kansas School of Medicine Selected publications
Blanchette M, Green RE, Macarthur S, Brooks AN, Brenner SE,
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