Dissecting the role of U5 snRNA isoforms as drivers of U5 snRNP diversity and spliceosome plasticity during development and homeostasis

• Applicant: Professorin Dr. Mirka Uhlirova
• Subject Area: General Genetics and Functional Genome Biology ; Developmental Biology ; Cell Biology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 497801021

Pre-mRNA splicing represents a crucial step in the regulation of gene expression in metazoans pivotal to tissue and organ development, homeostasis, and organismal healthspan. The “cut and join” process catalyzed by a spliceosome must be efficient and precise but also flexible to generate specific transcripts on demand. In contrast, mutations in, and deregulation of, spliceosome components underlie numerous human diseases and organismal aging. The capacity to generate diverse cell-type-specific splicing patterns has been linked to the dynamic composition of the spliceosome. The spliceosome consists of five small nuclear ribonucleoprotein particles (snRNPs) each comprising of specific uridine-rich small nuclear RNA (U snRNA), and a set of core and accessory proteins. Intriguingly, higher eukaryotes, unlike yeast, encode several isoforms of individual U snRNAs, which show specific spatiotemporal expression. Their roles and contribution to the dynamic spliceosome architecture and functional plasticity remain largely unknown. Our work, using the genetically tractable Drosophila model, has provided novel insights into mechanisms governing spliceosome biogenesis, function, and regulation (Claudius et al., 2015, Erkelenz et al., 2021). Moreover, we have demonstrated its relevance for mechanistic studies of etiology and pathology of a degenerative eye disorder retinitis pigmentosa caused by mutations in the core splicing factor Prp8 (Stankovic et al., 2020). Here we propose to combine functional genetics, genomic and proteomic approaches in the Drosophila model to unravel the tissue- and developmental-stage specific requirements for the seven U5 snRNA isoforms encoded in the fly genome. We will determine the role of the individual U5 snRNA isoforms in shaping the U5 snRNP composition and their contribution to establishing the developmental stage- and tissue-specific splicing programs. Finally, we will define the in vivo function of the U5 snRNA• RNA base-pairing interactions as a part of the late checkpoint mechanism for splice site selection and the maintenance of transcriptome integrity. We believe that our work will be of general importance for basic and biomedical research, advancing the understanding of mechanisms that control canonical and alternative pre-mRNA splicing in metazoans.

• DFG Programme: Research Grants