Zrsr2 Is Essential for the Embryonic Development and Splicing of Minor Introns in RNA and Protein Processing Genes in Zebrafish.

ZRSR2 (zinc finger CCCH-type, RNA binding motif and serine/arginine rich 2) is an essential splicing factor involved in 3' splice-site recognition as a component of both the major and minor spliceosomes that mediate the splicing of U2-type (major) and U12-type (minor) introns, respectively. Studies of -depleted cell lines and -mutated patient samples revealed its essential role in the U12-dependent minor spliceosome. However, the role of during embryonic development is not clear, as its function is compensated for by in mice. Here, we utilized the zebrafish model to investigate the role of during embryonic development. Using CRISPR/Cas9 technology, we generated a -knockout zebrafish line, termed (p.Trp167Argfs*9) and examined embryo development in the homozygous mutant embryos. embryos displayed multiple developmental defects starting at 4 days post fertilization (dpf) and died after 8 dpf, suggesting that proper Zrsr2 function is required during embryonic development. The global transcriptome analysis of 3 dpf embryos revealed that the loss of Zrsr2 results in the downregulation of essential metabolic pathways and the aberrant retention of minor introns in about one-third of all minor intron-containing genes in zebrafish. Overall, our study has demonstrated that the role of Zrsr2 as a component of the minor spliceosome is conserved and critical for proper embryonic development in zebrafish.