Role of Ecd in spliceosome function and glial homeostasis in the Drosophila nervous system

Abstract

Pre-mRNA splicing, which is carried out by the spliceosome, is essential for gene regulation facilitating differentiation of different cell types within multicellular organisms. Defective splicing can have detrimental effects on cellular viability and function. Disruption of spliceosome components often produces cell-type specific phenotypes, particularly in the brain, with neurons and glia exhibiting distinct sensitivities. However, knowledge of spliceosome function in the nervous system remains unbalanced, with glial roles far less understood than in neurons. Using the Drosophila central nervous system as a model, I investigated the impact of spliceosome dysfunction in glial cells, by manipulating Ecdysoneless (Ecd), a critical biogenesis factor of spliceosomal U5 snRNP. My results show that glial-specific ecd knockdown reduced larval brain size, and caused pupal lethality. Closer examination of the developing brains revealed induction of stress-dependent translational response and AP-1-mediated transcriptional response, associated with nuclear hypertrophy and changes to nucleolar architecture. Genetic interaction experiments implicated transcription factors Xrp1 and Irbp18 in regulating nuclear morphology downstream of spliceosome malfunction. Shortening of lifespan observed upon adult-specific ecd knockdown further indicate the requirement for glial spliceosome integrity during adulthood. Finally, I performed a detailed analysis of the translational reporter to assess the contribution of individual elements to stress-responsive translation. Together, these findings link spliceosome fidelity to stress signalling, translational control and nuclear organization in glial cells, emphasizing the critical role of cell-type specific RNA processing in maintaining brain homeostasis.