Requirement for highly efficient pre-mRNA splicing during Drosophila early embryonic development (2014). Leonardo Gastón Guilgur, Pedro Prudêncio, Daniel Sobral, Denisa Liszekova, André Rosa, Rui Gonçalo Martinho. eLife 2014;3:e02181.
Drosophila syncytial nuclear divisions limit transcription unit size of early zygotic genes. As mitosis inhibits not only transcription, but also pre-mRNA splicing, we reasoned that constraints on splicing were likely to exist in the early embryo, being splicing avoidance a possible explanation why most early zygotic genes are intronless. We isolated two mutant alleles for a subunit of the NTC/Prp19 complexes, known to be important for efficient spliceosome activation, which specifically impaired pre-mRNA splicing of early zygotic but not maternally encoded transcripts. Since these splicing defects were not related to any particular structure/sequence of the early zygotic transcripts, nor resulted from a differential association of spliceosomal components to the NTC/Prp19 complexes, we hypothesized that the requirements for pre-mRNA splicing efficiency were likely to vary during development. Ectopic maternal expression of an early zygotic pre-mRNA was sufficient to suppress its splicing defects in the mutant background. Furthermore, a small early zygotic transcript with multiple introns was poorly spliced in wild-type embryos. Our findings demonstrate for the first-time the existence of a developmental pre-requisite for highly efficient splicing during Drosophila early embryonic development and suggest in highly proliferative tissues a need for coordination between cell cycle and gene architecture to ensure correct gene expression and avoid abnormally processed transcripts.