NineTeen Complex-subunit Salsa is required for efficient splicing of a subset of introns and dorsal–ventral patterning

Abstract

The NineTeen Complex (NTC), also known as pre-mRNA-processing factor 19 (Prp19) complex, regulates distinct spliceosome conformational changes necessary for splicing. During Drosophila midblastula transition, splicing is particularly sensitive to mutations in NTC-subunit Fandango, which suggests differential requirements of NTC during development. We show that NTC-subunit Salsa, the Drosophila ortholog of human RNA helicase Aquarius, is rate-limiting for splicing of a subset of small first introns during oogenesis, including the first intron of gurken. Germline depletion of Salsa and splice site mutations within gurken first intron impair both adult female fertility and oocyte dorsal-ventral patterning, due to an abnormal expression of Gurken. Supporting causality, the fertility and dorsal-ventral patterning defects observed after Salsa depletion could be suppressed by the expression of a gurken construct without its first intron. Altogether, our results suggest that one of the key rate-limiting functions of Salsa during oogenesis is to ensure the correct expression and efficient splicing of the first intron of gurken mRNA. Retention of gurken first intron compromises the function of this gene most likely because it undermines the correct structure and function of the transcript 5 ′ ′ ′ ′ ′ UTR.

Polycomb group (PcG) proteins prevent the assembly of abnormal synaptonemal complex structures during meiosis

“…Phenotypic classes are identical to the ones reported in Rathore et al. ( 56 ). Number of scored eggs is shown on the top of each bar.…”

“…6 E ). Contrary to depletion of Salsa RNA helicase ( 56 ) and mutants for meiotic DNA repair ( 57 , 58 ), depletion of Sfmbt was not associated with significant dorsal-ventral patterning defects of the eggshell (fused dorsal appendages; Fig. 6 D ; class 2 and 3) or abnormal morphology of the oocyte karyosome ( Fig.…”

“…( C ) Egg laying was significantly reduced after germ line depletion of Sfmbt. Depletion of Salsa (salsa RNAi) was used as a positive control for reduced egg laying ( 56 ). Average ± SD of two biological replicas.…”

“…Eggs laid by females whose germ line was depleted for Sfmbt were typically short (class 3: short eggs). Depletion of Salsa was used as a positive control for eggshell dorsal-ventral patterning defects ( 56 ). Phenotypic classes are identical to the ones reported in Rathore et al.…”

The PRP19 Ubiquitin Ligase, Standing at the Cross-Roads of mRNA Processing and Genome Stability

“…A stronger non-sense fandango mutation led to complete loss of the female germline in adult ovaries indicating that a lower level of Fandango is required for splicing of maternal transcripts [ 94 ]. Similarly, mutation of Salsa , the drosophila homolog of Aquarius , a PRP19-associated RNA helicase, also impairs splicing of a subset of small first introns during oogenesis [ 95 ]. Altogether, this data indicates that splicing efficiency requirements vary during development and that highly proliferative tissues need to coordinate cell cycle progression and gene architecture to avoid RNA transcription and maturation issues.…”