ABSTRACT The central goal of this project is to understand fundamental mechanisms of human pre-mRNA splicing, a required step in the expression of most eukaryotic genes, as well as the regulation of alternative splicing. Specific mechanisms through which exons and introns are correctly identified by the spliceosome will continue to be investigated. These studies will focus on recognition of the canonical and non-canonical splice sites by snRNAs and RNA-binding proteins, and on contextual effects due to other pre-mRNA features, such as splicing enhancer elements recognized by SR proteins. The mechanisms of action and specificity of antisense-oligonucleotide and small- molecule splicing modulators will be explored, as will the interplay between alternative splicing and chromatin. In addition, the network of protein-protein interactions of the SR protein SRSF1 will continued to be investigated, with the goal of obtaining structural insights about its various functions in splicing. This project will rely on integrative approaches, including molecular, bioinformatics, biochemical, biophysical, proteomics, cell biology, and pharmacological techniques, as well as in vitro, cell-based, and in vivo assays. In addition to obtaining new insights into basic mechanisms of gene expression, these studies will improve the understanding of numerous mutations associated with various genetic diseases, as well as facilitate correct genetic diagnosis and therapeutics development for such diseases.