Alternative Splicing Regulation of hnRNP A1 and RALY

Abstract

Part I hnRNP A1 regulates alternative splicing of Tau exon 10 by targeting 3’ splice sites The ratio control of 4R-Tau/3R-Tau by alternative splicing of Tau exon 10 is important for maintaining brain functions. In this study, I show that hnRNP A1 knockdown induces inclusion of endogenous Tau exon 10, conversely, overexpression of hnRNP A1 promotes exon 10 skipping of Tau. In addition, hnRNP A1 inhibits splicing of intron 9, but not intron 10. Furthermore, hnRNP A1 directly interacts with the 3’ splice site of exon 10 to regulate its functions in alternative splicing. Finally, gene ontology analysis demonstrates that hnRNP A1-induced splicing and gene expression targets a subset of genes with neuronal function. Part II Splicing activity of RALY directly targets poly-uridine sequences RBP associated with lethal yellow mutation (RALY) is a member of the heterogeneous nuclear ribonucleoprotein family (hnRNP). Although the role of RALY in transcription has been studied previously, its splicing activity remains unclear. Here, I apply the Fas minigene system to demonstrate that RALY regulates splicing by targeting poly-uridine in pre-mRNA. Moreover, analysis of various structural domains presented in RALY show that RNA recognition motif (RRM), basic and acidic domains are required for its splicing functions, and the other domains, such as, variable domain and leucine zipper domain do not play important role in this activity. In addition, variable and basic domains are required for its localization in the nucleus, indicating different functions of each domain. My results show that the splicing activity of RALY occurs by directly targeting poly-uridine sequences, and that three structural domains of RALY are required for its splicing activity.