Abstract
The spliceosome cycle consists of assembly, catalysis, and recycling phases. Recycling of postspliceosomal U4 and U6 small nuclear ribonucleoproteins (snRNPs) requires p110/SART3, a general splicing factor. In this article, we report that the zebrafish earl grey (egy) mutation maps in the p110 gene and results in a phenotype characterized by thymus hypoplasia, other organ-specific defects, and death by 7 to 8 days postfertilization. U4/U6 snRNPs were disrupted in egy mutant embryos, demonstrating the importance of p110 for U4/U6 snRNP recycling in vivo. Surprisingly, expression profiling of the egy mutant revealed an extensive network of coordinately up-regulated components of the spliceosome cycle, providing a mechanism compensating for the recycling defect. Together, our data demonstrate that a mutation in a general splicing factor can lead to distinct defects in organ development and cause disease.